ES In Walking References

Abraham L.D., Marks W.B., and Loeb G.E. (1985) The distal hindlimb musculature of the cat. Cutaneous reflexes during locomotion. Exp. Brain Res. 58, 594-603.
Abstract: In order to better understand the organization of the locomotor control system, we examined the temporal patterns of distal hindlimb muscle responses to brief electrical stimulation of cutaneous nerves during walking on a treadmill. Electromyographic recordings were made from twelve muscles; stimuli were applied individually to three nerves at random times throughout the step cycle. A new graphical technique was developed to assist detailed examination of the time course and gating of complex reflex patterns. The short latency reflexes were of two primary types: inhibition of extensors and excitation of flexors; these responses were only evident during locomotor phases in which the respective motoneuron pools were active. Longer-latency response components were gated in a similar but not identical manner, suggesting some independence from the basic locomotory influence on the motoneuronal pool. The phase-dependent gating of reflexes appeared to be consistent with a functional role for reflex responses during locomotion. The reflex responses of muscles with complex anatomical actions were often correspondingly complex

Alway S.E., Hughson R.L., Green H.J., Patla A.E., and Frank J.S. (1987) Contractile properties of the human triceps surae following prolonged exercise and beta-blockade. Clin. Physiol 7, 151-163.
Abstract: Sixteen healthy males volunteered to perform both an incremental maximal and prolonged submaximal treadmill test with beta-blockade (2 X 80 mg oral propranolol per day) or matched placebo in a blind crossover design. Prior to and following the prolonged exercise, electrical stimulation of the triceps surae was performed to examine contractile properties. During the maximal test, the heart rate (HR) was reduced at all times by beta-blockade. The time to exhaustion in this test was significantly reduced by beta-blockade (P less than 0.03), while the maximal oxygen uptake (VO2 max) was not significantly lower (P = 0.06). In response to prolonged treadmill walking at 60% of VO2 max, the HR was reduced but VO2, respiratory quotient and ventilation were not affected by beta-blockade relative to placebo. Plasma concentrations of free fatty acids increased during exercise in the placebo but not beta- blocked treatment (P less than 0.0001). Plasma noradrenalin and adrenalin increased with exercise; the increase in adrenalin with beta- blockade was greater than that with placebo (P less than 0.0001). The RPE obtained at intervals during the prolonged exercise were greater for beta-blockades than placebo. Eight of 16 subjects were unable to complete full 90 min with beta-blockade; but all 16 completed the test with placebo. The electrically evoked twitches in the triceps surae muscle group after exercise did not differ in peak torque or one-half relaxation time compared to pre-exercise. The time to peak twitch torque was significantly shorter after exercise. No differences in twitch were observed due to beta-blockade. The tetanic responses at 10, 20, 50 and 100 Hz were not affected by either exercise or the beta- blockade. In conclusion, an increased subjective estimate of fatigue (RPE) was observed during prolonged exercise with beta-blockade. This subjective fatigue did not relate to altered peripheral muscle force production during electrical stimulation. The results suggest either a central rather than peripheral origin of fatigue, or fatigue in a muscle group not examined by stimulation of the triceps surae

Andersen J.B. and Sinkjaer T. (1999) The stretch reflex and H-reflex of the human soleus muscle during walking. Motor Control 3, 151-157.
Abstract: Due to the complexity of applying a well-defined stretch during human walking, most of our knowledge about the short latency stretch reflex modulation in humans is based on H-reflex studies. To illuminate the difference between the two methodologies, both types of reflexes were evoked in the same subjects, same experiment. Stretch reflexes were evoked via a stretch device capable of evoking stretch reflexes of the human soleus muscles during walking. H-reflexes were elicited by an electrical stimulation of the tibial nerve at the popliteal fossa at the knee. A significantly different modulation of the two reflexes was found in the late stance where the stretch reflex decreased in relation to the H-reflex. This was consistent with the unloading of the muscle spindles during the push-off in the late stance, suggesting a complex alpha-gamma coactivation, if any, at this time of the step. The soleus stretch reflex and H-reflex were compared during the stance phase of walking and sitting at matched soleus activity. No difference was found in the amplitude of the stretch reflex. However, there was a significant decrease of the H-reflex during the stance phase of walking, consistent with a task-specific presynaptic mediated reflex control. It is proposed that the short latency stretch reflex during walking is not sensitive to such a presynaptic inhibition

Angel A. and Clarke K.A. (1975) An analysis of the representation of the forelimb in the ventrobasal thalamic complex of the albino rat. J. Physiol 249, 399-423.
Abstract: 1. Glass micro-electrodes have been used to record from a total of 998 units situated in the ventrobasal thalamic complex in the deeply anaesthetized albino rat. 2. Of these units 889 responded to electrical stimulation of the contralateral forelimb and fifty-one to the contralateral hind limb. The remaining units consisted of those with receptive fields on the trunk, head and those which responded to stimulation of more than one limb. Only the latter group of units showed any spontaneous activity in the absence of intentional stimulation. 2. Of the units which responded to electrical stimulation of the contralateral forelimb the receptive fields, modality and latencies of response were accurately determined for 505 units. The mean latency to supramaximal stimulation at the wrist was 4.49 (+/- 0.04 S.E. of mean) msec; and to mechanical stimulation (for 146 of these units) at the centre of the receptive field 6.58 (+/- 0.12) msec. The modalities were distributed as follows: light pressure, 391; heavy pressure, 47; hair movement, 40; claw sensitive, 15 and joint movement, 12 units. 4. The forelimb representation within the ventrobasal thalamic complex was somatotopically organized, the over-all appearance being that of an incompletely closed fist, palmar surface uppermost, thumb media, with the wrist caudal and the digital tips rostral and dorsal. 5. The central projection was distorted, some parts showing expanded representation, notably the tips of digits II and III and the medial wrist pad. Other parts were contracted, e.g. the wrist, forearm and shoulder. 6. Units with receptive fields consisting of the whole of a walking pad had shorter mean latencies, to tactile stimulation, than those whose field was a single spot on a pad. 7. Units were found to show an abolute unresponsive time to the second of a pair of identical supramaximal electrical stimuli of up to 50 msec, and a relative unresponsive time which could last up to 500 msec. The absolute unresponsive and relative unresponsive times to the second of a pair of tactile stimuli was shorter being 30 and 150 msec respectively. 8. The effect of decortication was to increase the excitability of thalamic units to peripheral stimulation both in the initial and later discharges

Aniss A.M., Gandevia S.C., and Burke D. (1992) Reflex responses in active muscles elicited by stimulation of low- threshold afferents from the human foot. J. Neurophysiol. 67, 1375-1384.
Abstract: 1. Reflex responses were elicited in muscles that act at the ankle by electrical stimulation of low-threshold afferents from the foot in human subjects who were reclining supine. During steady voluntary contractions, stimulus trains (5 pulses at 300 Hz) were delivered at two intensities to the sural nerve (1.2-4.0 times sensory threshold) or to the posterior tibial nerve (1.1-3.0 times motor threshold for the intrinsic muscles of the foot). Electromyographic (EMG) recordings were made from tibialis anterior (TA), peroneus longus (PL), soleus (SOL), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles by the use of intramuscular wire electrodes. 2. As assessed by averages of rectified EMG, stimulation of the sural or posterior tibial nerves at nonpainful levels evoked a complex oscillation with onset latencies as early as 40 ms and lasting up to 200 ms in each muscle. The most common initial responses in TA were a decrease in EMG activity at an onset latency of 54 ms for sural stimuli, and an increase at an onset latency of 49 ms for posterior tibial stimuli. The response of PL to stimulation of the two nerves began with a strong facilitation of 44 ms (sural) and 49 ms (posterior tibial). With SOL, stimulation of both nerves produced early inhibition beginning at 45 and 50 ms, respectively. With both LG and MG, sural stimuli produced an early facilitation at 52-53 ms. However, posterior tibial stimuli produced different initial responses in these two muscles: facilitation in LG at 50 ms and inhibition in MG at 51 ms. 3. Perstimulus time histograms of the discharge of 61 single motor units revealed generally similar reflex responses as in multiunit EMG. However, different reflex components were not equally apparent in the responses of different single motor units: an individual motor unit could respond slightly differently with a change in stimulus intensity or background contraction level. The multiunit EMG record represents a global average that does not necessarily depict the precise pattern of all motor units contributing to the average. 4. When subjects stood erect without support and with eyes closed, reflex patterns were seen only in active muscles, and the patterns were similar to those in the reclining posture. 5. It is concluded that afferents from mechanoreceptors in the sole of the foot have multisynaptic reflex connections with the motoneuron pools innervating the muscles that act at the ankle. When the muscles are active in standing or walking, cutaneous feedback may play a role in modulating motoneuron output and thereby contribute to stabilization of stance and gait

Apps R. and Lee S. (1999) Gating of transmission in climbing fibre paths to cerebellar cortical C1 and C3 zones in the rostral paramedian lobule during locomotion in the cat. J. Physiol 516 ( Pt 3), 875-883.
Abstract: 1. Climbing fibre field potentials evoked by low intensity (non- noxious) electrical stimulation of the ipsilateral superficial radial nerve have been recorded in the rostral paramedian lobule (PML) in awake cats. Chronically implanted microwires were used to monitor the responses at eight different C1 and C3 zone sites during quiet rest and during steady walking on a moving belt. The latency and other characteristics of the responses identified them as mediated mainly via the dorsal funiculus-spino-olivocerebellar path (DF-SOCP). 2. At each site, mean size of response (measured as the area under the field, in mV ms) varied systematically during the step cycle without parallel fluctuations in size of the peripheral nerve volley. Largest responses occurred overwhelmingly during the stance phase of the step cycle in the ipsilateral forelimb while smallest responses occurred most frequently during swing. 3. Simultaneous recording from pairs of C1 zone sites located in the anterior lobe (lobule V) and C1 or C3 zone sites in rostral PML revealed markedly different patterns of step- related modulation. 4. The findings shed light on the extent to which the SOCPs projecting to different parts of a given zone can be regarded as functionally uniform and have implications as to their reliability as channels for conveying peripheral signals to the cerebellum during locomotion

Armstrong D.M. and Drew T. (1984) Locomotor-related neuronal discharges in cat motor cortex compared with peripheral receptive fields and evoked movements. J. Physiol 346, 497-517.
Abstract: Discharge patterns of motor cortical neurones in cats walking steadily on a moving belt have been compared with other functional characteristics of the neurones. In forelimb motor cortex rhythmic discharges occurred in cells with peripheral receptive fields in all parts of the contralateral forelimb and also in cells with no discernible receptive field. Cells discharging at similar times during the step cycle often had very different receptive fields and cells with similar receptive fields (including neighbouring cells) could discharge at similar or at quite different times. In cells with a cutaneous receptive field including the forefoot the discharges during locomotion remained rhythmic (and their phasing relative to the step cycle was unchanged) when the response to mechanical stimulation in the receptive field was temporarily much reduced or abolished by local anaesthesia of the skin. The proportion of neurones showing accelerated firing during different parts of the step cycle fluctuated more for antidromically identified pyramidal tract neurones (p.t.n.s) than for non-p.t.n.s and was highest during the second half of stance in the contralateral forelimb and lowest during swing. When the neurones were subdivided according to the movement evoked by threshold electrical stimulation through the micro-electrode, p.t.n.s and non-p.t.n.s recorded by electrodes evoking elbow flexion showed a wide variety of discharge patterns. For p.t.n.s the discharge rate reached an average of 69 impulses/s during late stance and declined to an average of 26 impulses/s during swing

Babic J., Karcnik T., and Bajd T. (2001) Stability analysis of four-point walking. Gait. Posture. 14, 56-60.
Abstract: The aim of the experiment reported here was to determine the static and dynamic stability of two-point stance phases when walking on hands and knees at different speeds. In addition, we defined the methods and predicted the consequences of including two-point stance phases into crutch assisted functional electrical stimulation (FES) walking. Crawling on hands and knees was performed at three speeds by five healthy male persons. With twelve joint-position markers placed on the subject, we determined two stability indices for every instant of gait. We analysed the peak values of these two indices during the two-point stance phases. The results indicate that we have to ensure the proper position of the centre of gravity to increase the speed of walking. To reach speeds, lower than 0.6 m/s, it is not necessary to include statically unstable phases. The shift of the centre of gravity towards and across the leading stability edge can result in getting into the dynamically unstable state. Considering the results we can effectively introduce two-point stance phases into crutch assisted FES walking and therefore increase the speed and energy effectiveness of walking

Bajd T., Kralj A., Turk R., Benko H., and Sega J. (1983) The use of a four-channel electrical stimulator as an ambulatory aid for paraplegic patients. Phys. Ther. 63, 1116-1120.
Abstract: This article reports the use of electrical stimulation to provide paraplegic patients with complete lesions of the spinal cord the ability to rise from sitting to standing, to maintain a standing position, and to walk with a reciprocal gait. Four channels of electrical stimulation are sufficient for synthesis of a simple reciprocal gait pattern in these patients. During the double-stance phase, knee extensor muscles of both knees are stimulated, providing sufficient support for the body. Only one knee extensor muscle group is excited during the single-stance phase. The swing phase of the contralateral lower extremity is accomplished by eliciting the synergistic flexor muscle response through electrical stimulation of afferent nerves. The transition from the double-stance phase to the swing phase is controlled by two hand switches used by the therapist or built into the handles of the walking frame or crutches for use by the patient

Bajd T., Andrews B.J., Kralj A., and Katakis J. (1985) Restoration of walking in patients with incomplete spinal cord injuries by use of surface electrical stimulation--preliminary results. Prosthet. Orthot. Int. 9, 109-111.
Abstract: A group of patients who are good candidates for the application of Functional Electrical Stimulation (FES) to restore reciprocal walking is described. They have incomplete lesions of the spinal cord. Because of the degree of preserved voluntary control, proprioception and sensation some of these patients can achieve crutch assisted walking by means of multichannel electrical stimulation. In a number of cases the patient has sufficient strength and voluntary control in the upper limbs and at least one leg to provide safe standing for short periods in forearm crutches. For these patients a two channel stimulator controlled by a handswitch was applied to achieve safe and practical crutch assisted walking in a relatively short period of time

Bajd T., Kralj A., Turk R., and Benko H. (1990) Symmetry of FES responses in the lower extremities of paraplegic patients. J. Biomed. Eng 12, 415-418.
Abstract: Due to natural or artificial obstacles, gait is a less automatic and periodic process than it would appear when studying normal walking on the level. Pre-programmed functional electrical stimulation (FES) sequences, therefore, do not appear to be a suitable approach to the control of multichannel electrical stimulators in the restoration of paraplegic walking. Walking in paraplegic subjects must be, to a large extent, under voluntary control. To lessen the burden of this control, the symmetry of walking can be taken into account. Symmetric motion of the legs requires symmetric FES actuation. Symmetry of FES responses was studied in a group of 10 paraplegic subjects who had all undergone the FES training program. Recruitment curve, fatigue index and twitch delay were assessed. An average 80% symmetry was found in all parameters measured, thus allowing a reduction of complexity of control approach for FES locomotor aids

Bajd T., Kralj A., and Zefran M. (1993) Unstable states in four-point walking. J. Biomed. Eng 15, 159-162.
Abstract: The presently utilized walking patterns in paraplegic subjects with complete spinal cord injury (SCI) are compared by the help of graphic representations. Improved four-point gait assisted by functional electrical stimulation (FES) and crutches is proposed by introducing unstable states into the walking sequence. The unstable states are defined as passive phases of walking where the centre of mass (COM) is gravity driven in the direction of progression. The unstable state is described by a simple inverted pendulum model. Kinematic measurements of the unstable state were performed in normal and paraplegic subjects

Bajd T., Stefancic M., Matjacic Z., Kralj A., Savrin R., Benko H., Karcnik T., and Obreza P. (1997) Improvement in step clearance via calf muscle stimulation. Med. Biol. Eng Comput. 35, 113-116.
Abstract: The aim is to study the influence of electrically stimulated calf muscles on the effectiveness of the swinging leg movement. The study is carried out with a group of patients with incomplete spinal cord injuries both under stationary conditions and during crutch-assisted walking. Before stimulation is applied to the ankle plantar flexors, the knee extensors are inactivated. In each cycle, after ankle plantar flexor stimulation, peroneal stimulation is started, triggering the flexion reflex. From a biomechanical point of view, functional electrical stimulation (FES) of the ankle plantar flexors results in increased ground clearance of the lower extremity. Additionally, the FES-assisted lifting of the heel results in the elimination of extensor tone and thus shortens the swing time

Bajd T., Kralj A., Stefancic M., and Lavrac N. (1999) Use of functional electrical stimulation in the lower extremities of incomplete spinal cord injured patients. Artif. Organs 23, 403-409.
Abstract: After a program of therapeutic electrical stimulation, 3 groups of incomplete spinal cord injured (SCI) patients were identified, those in whom an improvement of both voluntary and stimulated muscle force was observed, those with an increase in stimulation response only, and patients in whom no effect of electrical stimulation training could be recorded. As it is difficult to predict the outcome of the electrical stimulation rehabilitation process, a diagnostic procedure was developed to predict soon after accidents which incomplete SCI patients are candidates for permanent use of a functional electrical stimulation (FES) orthotic aid. The candidates for chronic use of FES are patients with weak ankle dorsiflexors and sufficiently strong knee extensors. These patients are equipped with a single channel peroneal stimulator augmenting dorsiflexion and knee and hip flexion in a total lower limb flexion response. By applying FES to the ankle plantar flexors, the swing phase of walking can be significantly shortened and faster walking obtained

Barbeau H., Norman K., Fung J., Visintin M., and Ladouceur M. (1998) Does neurorehabilitation play a role in the recovery of walking in neurological populations? Ann. N. Y. Acad. Sci. 860, 377-392.
Abstract: This review demonstrates that neurorehabilitation approaches, based on recent neuroscience findings, can enhance locomotor recovery after a spinal cord injury or stroke. Findings are presented from more than 20 clinical studies conducted by numerous research groups on the effect of locomotor training using either body weight support (BWS), functional electrical stimulation (FES), pharmacological approaches or a combination of them. Among the approaches, only BWS-assisted locomotor training has been demonstrated to have a greater effect than conventional or locomotor training alone. However, when study results were combined and weighted for the number of subjects, the results indicated that there is a gradient of effects from small changes with the immediate application of FES or BWS to larger changes when locomotor training is combined with FES or BWS or pharmacological approaches. The findings of these studies suggest that these neurorehabilitation approaches do play a role in the recovery of walking in subjects with spinal cord injury or stroke. Several factors contribute to the potential for recovery including the site, etiology, and chronicity of the injury, as well as the type, duration, and specificity of the intervention and whether interventions are combined. Furthermore, how these neurorehabilitation approaches may take advantage of the plasticity process following neurological lesion is also discussed

Beillot J., Carre F., Le Claire G., Thoumie P., Perruoin-Verbe B., Cormerais A., Courtillon A., Tanguy E., Nadeau G., Rochcongar P., and Dassonville J. (1996) Energy consumption of paraplegic locomotion using reciprocating gait orthosis. Eur. J. Appl. Physiol Occup. Physiol 73, 376-381.
Abstract: The energy cost of walking using a reciprocating gait orthosis (RGOII) with functional electrical stimulation (FES) was assessed in 14 patients with spastic complete paraplegia from six rehabilitation centres. Before and after training asing RGOII with FES, the subjects performed a progressive maximal test on an arm-crank ergometer to obtain their laboratory peak oxygen uptake (LVO2peak), heart rate (HR) and blood lactate concentration changes. At the end of the training session, oxygen uptake (VO2) was measured during a walking test with orthosis at different speeds (6 min steady state at 0.1 m.s-1, followed by 2-min stages at progressively increasing speeds up to exhaustion). Of the subjects 4 repeated this test using orthosis without FES. At a speed of 0.1 m.s-1, VO2 represented 47 (SD 23)% of LVO2peak, mean HR was 137 (SD 21) beats.min-1 and mean blood lactate concentration 2.4. (SD 1.4) mmol.l-1. Maximal speed ranged from 0.23 to 0.5 m.s-1. At maximal speed, VO2 was 91 (SD 18)% of LVO2peak, mean HR reached 96 (SD 7)% and mean blood lactate concentration only 52 (SD 19)% of the maximal values measured during the laboratory test. Walking without electrical stimulation induced an increase in HR but there was no difference in VO2 and blood lactate compared to walking with stimulation. The training period did not result in any improvement in maximal physiological data. We concluded that the free cadence walking speed with orthosis remains much lower than that of able-bodied people or wheelchair users. The metabolic cost at a given speed is much higher even if, using a stimulation device, the cardiovascular stress is reduced

Betz R., Boden B., Triolo R., Mesgarzadeh M., Gardner E., and Fife R. (1996) Effects of functional electrical stimulation on the joints of adolescents with spinal cord injury. Paraplegia 34, 127-136.
Abstract: Nineteen adolescent subjects with complete spinal cord injuries resulting in paraplegia or tetraplegia participated in a functional electrical stimulation (FES) program consisting of computerized, controlled exercise and/or weight bearing. The effects of stimulated exercise and standing/walking on the lower extremity joints were prospectively studied. Plain radiographs and MRIs were obtained prior to and following completion of the exercise and standing and walking stages. In addition, the joints of five subjects were studied with synovial biopsies, arthroscopy, and the analysis of serum and synovial fluid for a 550 000 dalton cartilage matrix glycoprotein (CMGP). Pre- exercise joint abnormalities secondary to the spinal cord injury improved following the stimulation program. None of the subjects developed Charcot joint changes. Upon standing with FES, one subject with poor hip coverage prior to participation developed hip subluxation which required surgical repair. No other detrimental clinical effects occurred in the lower extremity joints of subjects participating in an FES program over a 1-year period

Bevengut M., Libersat F., and Clarac F. (1986) Dual locomotor activity selectively controlled by f. Neurosci. Lett. 66, 323-327.
Abstract: The crab Carcinus maenas walks laterally; moreover, as soon as leg contact with the support is lost, it starts swimming. In free-moving animals, discharges from individual f

Biering-Sorensen F., Gregersen H., Hagen E., Haugland M., Keith M., Larsen C.F., Leicht B.P., Nielsen F.H., Rabischong E., and Sinkjaer T. (2000) [Improved function of the hand in persons with tetraplegia using electric stimulation via implanted electrodes]. Ugeskr. Laeger 162, 2195-2198.
Abstract: Functional Electrical Stimulation (FES) is a controlled use of electrical stimulation of muscle contractions to obtain function. FES is utilised today in the treatment of spinal cord injured individuals for diaphragmatic pacing, bladder and bowel management, ejaculation, walking and hand function, as well as conditioning. We present The Freehand System, which consists of implanted electrodes to arm and hand muscles. This system has now been implanted in the first two Nordic tetraplegics. Candidates are tetraplegics with C5-6 lesions. After implantation it may take 6-8 months before the tetraplegic person can expect to use The Freehand System completely in daily life. The tetraplegic individual can choose between two grasps. The Freehand System can for some few very physically disabled tetraplegics be a good aid to increase their level of activities of daily living and independence. Continued development in the coming years may broaden the indications with benefit for more individuals

Bijak M., Hofer C., Lanmuller H., Mayr W., Sauermann S., Unger E., and Kern H. (1999) Personal computer supported eight channel surface stimulator for paraplegic walking: first results. Artif. Organs 23, 424-427.
Abstract: Today functional electrical stimulation (FES) is used among other treatments to restore hand and arm function, to restore mobility of the lower extremities, for phrenic pacing, and in cardiomyoplasty. Common to all FES applications is that they require careful setup of stimulation parameters. To improve these tasks, personal computer (PC) based software for stimulation parameter evaluation and data acquisition was written. First, the described software was used to mobilize paraplegic patients in conjunction with an 12C bus controlled 8 channel surface stimulator. Electrodes were placed on each leg on the m. quadriceps and m. gluteus for hip and knee extension and the peroneal nerve to elicit flexion reflex. The fourth channel was used to correspond to subjects' individual needs. The stimulation patterns for standing up, walking, and sitting down easily could be set up and optimized by adjusting up to 128 stimulation parameters in a task- specific way

Bobet J. (1998) Can muscle models improve FES-assisted walking after spinal cord injury? J. Electromyogr. Kinesiol. 8, 125-132.
Abstract: Some persons with a spinal cord injury can use functional electrical stimulation (FES) to walk again, but many cannot, and for those that can the walking obtained is limited. This paper argues that muscle models can help improve FES systems, but only if these muscle models are enhanced. Part 1 reviews differences between muscle models for FES systems and those for "natural" movement; FES models emphasize limb angle, demand simplicity, exploit feedback, and grade force through recruitment rather than rate coding. Part 2 tells how FES systems have used muscle models. Those that do not use muscle models to control stimulation do not fare well, although two recent ones (rule-based control and neural-net control with feedback) may yet do so. Those that do use muscle models provide good control initially, but fare poorly as the muscle properties change. Part 3 lists important questions that muscle models must address: questions of goal, type of activation, spasticity, simulation, simplicity, and fatigue. If these features can be incorporated, models can improve both the design and control of FES systems

Bogataj U., Kljajic M., Gros N., Acimovic R., Malezic M. (1994) The rehabilitation of gait after stroke: a comparison between conventional therapy and multichannel functional electrical stimulation therapy. Proc RESNA, 373-375.

Bogataj U., Gros N., Kljajic M., Acimovic –Janezic R. (1997) Enhanced rehabilitation of gait after stroke: a case report of a therapeutic approach using multichannel functional electrical stimulation. IEEE Trans. Rehabil. Eng. 5, 221-232.

Bogey R.A., Perry J., Bontrager E.L., Gronley J.K. (2000) Comparison of across-subject EMG profiles using surface and multiple indwelling wire electrodes during gait. J Electromyogr Kinesiol 10:255-259.

Botte M.J., Waters R.L., Keenan M.A. (1988) Orthopaedic management of the stroke patient:  Part 1: Pathophysiology, limb deformity and patient evaluation. Orthop Rev 27, 637-647.

Botte M.J., Bruffey J.D., Copp S.N., Colwell  C.W. (2000) Surgical reconstruction of acquired spastic foot and ankle deformity. Foot Ankle Clin. 5, 381-416.

Borges G., Ferguson K., and Kobetic R. (1989) Development and operation of portable and laboratory electrical stimulation systems for walking in paraplegic subjects. IEEE Trans. Biomed. Eng 36, 798-801.
Abstract: Two new stimulation systems have been designed for use in functional neuromuscular stimulation of paralyzed people; one is portable and one is a nonportable laboratory system. Compared to previous systems, these have greatly enhanced capabilities, especially in terms of memory capacity, expandability, and user interface. They are extensively operator programmable. The laboratory stimulation system was designed to provide quick turnaround time for stimulation pattern or program changes while maintaining complete compatibility with the portable system. The lab system will also accomodate external closed-loop control

Bowden D.M., Galkin T., and Rosvold H.E. (1975) Primate drinking system as defined by electrical stimulation of the brain (ESB). Physiol Behav. 15, 103-111.
Abstract: Four rhesus monkeys were examined by ESB for drinking sites in structures that had been previously demonstrated to support drinking behavior. Three yielded a significantly greater proportion of drinking sites than expected from the earlier study, and one yielded significantly less. As the exploration proceeded, the proportion of sites yielding drinking greatly increased in the drinkers and decreased in the nondrinker, and the ratio of stimulus-bound to nonstimulus-bound drinking sites increased in the drinkers but decreased in the nondrinker. Orienting responses decreased in both drinker and nondrinker as exploration proceeded. Two sites that had reliably supported drinking in the restraint chair failed to do so when telestimulated in a free environment, but instead yielded turning, walking, and climbing behavior. The results suggest that ESB-elicited drinking is determined by stimulation of several overlapping neural systems. These probably include ascending dopaminergic and cholinergic systems which are relatively thirst specific, and a nonspecific, cholinergic component of the reticular activating system which triggers the animal to execute a prepotent response which is specific to a given animal with a given history of stimulation under particular enviromental constraints. The learning of stimulus bound drinking is proposed to have its neural locus within the system which mediates the prepotent response, rather than in a thirst system or general activation system

Brandell B.R. (1982) Development of a universal control unit for functional electrical stimulation (FES). Am. J. Phys. Med. 61, 279-301.
Abstract: In collaboration with the College of Engineering the author has developed a laboratory, or clinic, based, battery operated "universal" control system, designed to improve disabled gait in upper motor neuron disabilities, especially stroke, hemiplegia, and cerebral palsy, by applying several channels of FES (Functional Electrical Stimulation) to the lower limb muscles while the patient is walking. The timing of the FES pulses, which can be applied to as many as six of the patient's muscles, is determined by potentiometer controlled one-shot timers, which are triggered by any of three switches in the sole of either shoe. Combinations of inverters, flip flops, AND gates and OR gates in the externally connected logic circuits determine the sequence of delays and pulses applied to the patient's muscles. This paper describes and diagrams some of the logic circuits and as an example of the possible application of the concept of a "universal" control unit reports the modifications of gait induced in a hemiplegic, four year post-stroke, patient. The characteristics of this patient's gait with FES in comparison to its characteristics without FES are demonstrated with motion picture frames, EMG recordings and graphic tracings of her right knee and ankle joint positions. They include more symmetrical timing of her right and left stance and swing phases, increased dorsiflexion of her right ankle in the swing phase, followed by a more distinct heel strike, and improved flexion--extension sequences of the knee and ankle joints and an increased heel rise in the stance phase. The author concludes that the gait characteristics of some hemiplegic patients will improve as they become adapted over a period of weeks or months to a control logic, which lessens their functional limitations by the use of a properly timed and amplified sequence of FES pulses. He suggests that the FES control requirements for individual patients should be determined experimentally with a control system "universally" adaptable to a wide range of disabilities, and that these control parameters could then determine the design of portable units, which may be used on a long term basis. These units would include only the operational options needed to duplicate the gait corrections found to be practicable for each individual patient, by the testing procedure, through a universal logic unit as described in this paper

Brandell B.R. (1986) The study and correction of human gait by electrical stimulation. Am. Surg. 52, 257-263.
Abstract: To gain a better understanding of the functions that the calf and vastus muscles perform in the human walking gait the author systematically increased the contractions of these muscles separately and in combination by applying Functional Electrical Stimulation (FES) to them, during walking tests performed by a subject with nonpathological gait, and a patient with a hemiplegic gait. A four- channel stimulator was used with foot switch activated control systems, which accurately sequenced the FES pulses and timed them in relation to the footswitch contacts. In normal gait FES applied to the calf muscles in the first third of the stance phase induced knee extension, but when applied later in the stance phase it increased the amount of plantar flexion and knee flexion at the push off. Strengthened vastus muscle contraction increased the amount and duration of stance phase knee extension, and interacted with the calf FES to increase the amount of heel rise at the push off. In the hemiplegic gait calf FES resulted in some increased knee flexion and ankle plantar flexion after the opposite heel strike, but a persistent lower limb extensor synergy prevented knee flexion from occurring simultaneously with plantar flexion and a heel rise, while the hemiplegic limb was still weight bearing

Braun Z., Mizrahi J., Najenson T., and Graupe D. (1985) Activation of paraplegic patients by functional electrical stimulation: training and biomechanical evaluation. Scand. J. Rehabil. Med. Suppl 12, 93-101.
Abstract: A training method for the activation of the lower limb muscles of paraplegics by functional electrical stimulation (FES) for standing and walking is described. It consists of a daily program which does not interfere with the normal routine of the patient. The treatment of four patients, paralysed form 7 to 30 years, is described. In these patients, a good standing position was achieved by stimulating the quadriceps, sometimes supplemented by the gluteus maximus or medius muscles. Gait was obtained by activation of the flexion reflex in a single stimulation and by tilting the trunk. Difficulties during gait were encountered due to the strong adduction of the legs. No mechanical support was required for locking of the lower limb joints. However, to maintain the equilibrium of the body, external support such as parallel bars, walker or Canadian crutches were used. During treatment gait improved due to reduction of spasticity and better stability of the body. Biomechanical measurements of weight bearing on the legs indicated values ranging between 41 to 65% of the body weight. During gait, a steady improvement of velocity was noted, with a parallel decrease in stance and stride times

Brissot R., Gallien P., Le Bot M.P., Beaubras A., Laisne D., Beillot J., and Dassonville J. (2000) Clinical experience with functional electrical stimulation-assisted gait with Parastep in spinal cord-injured patients. Spine 25, 501-508.
Abstract: STUDY DESIGN: Clinical evaluation of the Parastep method, a six-channel transcutaneous functional electrical stimulation device, in spinal cord- injured patients. OBJECTIVES: To investigate the motor performances of this new technique regarding energy expenditure and to evaluate its advantages and limitations, especially in social activities involving ambulation. METHODS: This study was conducted in 15 thoracic spine- injured patients. The lesion was complete except in two patients. The gait ability and the functional use were judged clinically. Energy cost was evaluated from heart rate, peak oxygen uptake, and lactatemia. RESULTS: Thirteen patients completed the training (mean: 20 sessions) and achieved independent ambulation with a walker. The mean walking distance, without rest, was 52.8 +/- 69 m, and the mean speed was 0.15 +/- 0.14 m/sec. One patient with incomplete lesion, who had been nonambulatory for 8 months after the injury, became able to walk without functional electrical stimulation after five sessions. The follow-up was 40 +/- 11 months. Five patients pursued using functional electrical stimulation-assisted gait as a means of physical exercise but not for ambulation in social activities. The patients experienced marked psychological benefits, with positive changes in their way of life. In three subjects, a comparison of physiologic responses to exercise between a progressive arm ergometer test and a walking test with the Parastep (Sigmedics, Inc., Northfield, IL) at a speed of 0.1 m/sec was performed, showing that the heart rate, the peak oxygen uptake, and lactatemia during gait were close to those obtained at the end of the maximal test on the ergometer. CONCLUSIONS: In spite of its ease of operation and good cosmetic acceptance, the Parastep approach has very limited applications for mobility in daily life, because of its modest performance associated with high metabolic cost and cardiovascular strain. However, it can be proposed as a resource to keep physical and psychological fitness in patients with spinal cord injury

Buford J.A. and Smith J.L. (1993) Adaptive control for backward quadrupedal walking. III. Stumbling corrective reactions and cutaneous reflex sensitivity. J. Neurophysiol. 70, 1102-1114.
Abstract: 1. Four cats were trained to walk backward (BWD) and forward (FWD) on a motorized treadmill. Mechanical (taps) or electrical (pulses) stimuli were applied to the dorsal or ventral aspect of the hind paw during swing or stance. Hindlimb kinematic data, obtained by digitizing 16-mm high-speed film, were synchronized with computer-analyzed electromyograms (EMG) recorded from anterior biceps femoris (ABF), vastus lateralis (VL), lateral gastrocnemius (LG), tibialis anterior (TA), and semitendinosus (ST). Responses to taps and pulses, as well as the modulation in cutaneous reflex sensitivity to pulses, were described for both walking directions and stimulus locations. 2. After dorsal taps that obstructed FWD swing, the hindlimb initially drew back away from the obstacle with knee flexion and ST activation, ankle extension with TA suppression and LG activation, and hip extension with ABF facilitation. Next, the limb was raised over the obstacle with resumed TA activity and enhanced knee and ankle flexion, and then compensatory knee and ankle extension positioned the limb for the ensuing stance phase. 3. For ventral taps that obstructed BWD swing, the initial response also tended to draw the limb away from the obstacle with hip and ankle flexion and TA facilitation and reduced knee flexion with weak VL facilitation and suppression of ST activity. Next, ST activity resumed as knee and ankle flexion raised the limb over the obstacle, and then compensatory extension completed the swing phase for BWD walking. Thus the initial kinematic and EMG responses to obstacles were opposite for BWD versus FWD swing, and these responses were consistent with active avoidance of the obstacles. Responses during BWD walking were subtle, however, compared with those for FWD. 4. After nonobstructing taps (ventral FWD, dorsal BWD), ST and TA activation and knee and ankle flexion were coincident, demonstrating that the aforementioned differences in responses to obstructing obstacles were not simply location dependent. Regardless of the direction of walking or the location of stimulation, taps applied during stance had little immediate kinematic effect, but the subsequent swing phase was usually exaggerated, as if the response was programmed to avoid any lingering obstacle. 5. Electrical pulses did not elicit the full-blown responses typically evoked by taps. The sequencing in activation of ST and TA characteristic after laps was absent after pulses, and there were rarely dramatic kinematic responses to pulses like those easily elicited by taps. There were, in fact, few differences in responses to electrical stimulation for BWD versus FWD walking.(ABSTRACT TRUNCATED AT 400 WORDS)

Burridge J., Taylor P., Hagan S., and Swain I. (1997) Experience of clinical use of the Odstock dropped foot stimulator. Artif. Organs 21, 254-260.
Abstract: The Odstock dropped foot stimulator (ODFS) is a simple functional electrical stimulation (FES) device for the correction of dropped foot. Improved reliability, fine control of stimulation parameters, and careful application and follow-up have let to 86% compliance. Data on 56 patients (50 patients with hemiplegia, 5 patients with multiple sclerosis, and 1 patient with spinal cord injury) who have used the system for between 6 and 18 months are presented and show a statistically significant increase in walking speed with the stimulator at 3 months of 14% (p < 0.001); decreased effort of walking, measured as physiological cost index (PCI), of 37% (p < 0.001); and statistically significant improvement in functional mobility tests and questionnaires. No statistically significant carryover was seen although 3 patients had sufficient improvement in active ankle control and gait parameters to no longer need the stimulator. Six patients who used the stimulator all day every day had a problem with skin irritation, which we have not yet been able to solve. Two patients discontinued use after experiencing increased spasticity in the calf

Burridge J.H., Taylor P.N., Hagan S.A., Wood D.E., and Swain I.D. (1997) The effects of common peroneal stimulation on the effort and speed of walking: a randomized controlled trial with chronic hemiplegic patients.  Clin. Rehabil. 11, 201-210.
Abstract: OBJECTIVE: To measure the effect of the Odstock Dropped Foot Stimulator (ODFS), a common peroneal stimulator, on the effort and speed of walking. DESIGN: A randomized controlled trial. SUBJECTS: Hemiplegic patients who had suffered a single stroke at least six months prior to the start of the trial whose walking was impaired by a drop-foot. INTERVENTIONS: The treatment, functional electrical stimulation (FES) group, used the stimulator and received a course of physiotherapy; the control group received physiotherapy alone. MAIN OUTCOME MEASURES: Changes in walking speed measured over 10 m and the effort of walking measured by physiological cost index (PCI). RESULTS: Thirty-two subjects completed the trial, 16 in the FES group and 16 in the control group. Mean increase in walking speed between the beginning and end of the trial was 20.5% in the FES group (when the stimulator was used), and 5.2% in the control group. Improvement was also measured in PCI with a reduction of 24.9% in the FES group (when the stimulator was used) and 1% in the control group. No improvement in these parameters was measured in the FES group when the stimulator was not used. CONCLUSION: Walking was statistically significantly improved when the ODFS was worn but no 'carry-over' was measured. Physiotherapy alone, in this group of subjects with established stroke, did not improve walking

Burridge J.H., Ladouceur M. (2001) Clinical and Therapeutic Applications of Neuromuscular Stimulation: A Review of Current Use and Speculation into Future Developments. Neuromodulation 4:147-154. [See Stroke and Brain-Injury references for abstract.]

Campbell J.M., Ball J. (1978) Energetics of Walking in Cerebral Palsy.  In: Waters R., et al: Energetics Application to the Study and Management of Locomotor Disabilities. Ortho Clin No Am 9,351-377.

Campbell J.M., Meadows P.M., Waters R.L., Wederich C., Jordan C. (1992) Improvement in Hemiplegic Gait with Multichannel, Implanted Electrical Stimulation System. Proc 14th International Conference of the IEEE EMGS Paris, France, 1366-1368.

Campbell J.M., Meadows P.M. (1992) Therapeutic FES:  From Rehabilitation to Neural Prosthetics. Assistive Technology 4, 4-18.

Carmick J. (1993) Clinical use of neuromuscular electrical stimulation for children with cerebral palsy, Part 1: Lower extremity. Phys. Ther. 73, 505-513.
Abstract: This report, part 1 of a two-part case report on the clinical use of neuromuscular electrical stimulation (NMES) for children with cerebral palsy, documents the functional changes that occurred with the application of NMES to the lower extremity of three male children, 1.6, 6.7, and 10 years of age, all with hemiplegia due to cerebral palsy. Neuromuscular electrical stimulation was used in conjunction with a dynamic-systems, task-oriented model of motor learning. The children tolerated NMES well and at times demonstrated carryover after the removal of NMES. The youngest child showed immediate change in the ability to walk and run symmetrically. The two older boys demonstrated significant improvement in locomotor efficiency in a short time, although they were of an age when this improvement was not expected. One boy's Physiological Cost Index (PCI) measurement (a measure of locomotor efficiency) improved fourfold, and the other boy's PCI measurement improved by a factor of two. The results show preliminary evidence for the usefulness of NMES as an adjunct to the physical therapy program for improving function in children with cerebral palsy

Cha K., Horch K.W., and Normann R.A. (1992) Mobility performance with a pixelized vision system. Vision Res. 32, 1367-1372.
Abstract: A visual prosthesis, based on electrical stimulation of the visual cortex, has been suggested as a means for partially restoring functional vision in the blind. The prosthesis would create a pixelized visual sense consisting of punctate spots of light (phosphenes). The present study investigated the feasibility of achieving visually-guided mobility with such a visual sense. Psychophysical experiments were conducted on normally sighted human subjects, who were required to walk through a maze which included a series of obstacles, while their visual input was restricted to information from a pixelized vision simulator. Walking speed and number of body contacts with obstacles and walls were measured as a function of pixel number, pixel spacing, object minification, and field of view. The results indicate that a 25 x 25 array of pixels distributed within the foveal visual area could provide useful visually guided mobility in environments not requiring a high degree of pattern recognition

Chan V.W., Nazarnia S., Kaszas Z., and Perlas A. (1999) The impact of saline flush of the epidural catheter on resolution of epidural anesthesia in volunteers: a dose-response study. Anesth. Analg. 89, 1006-1010.
Abstract: We evaluated the effect of 1, 20, and 40 mL of epidural saline flush on recovery from lidocaine epidural anesthesia. Eight volunteers were studied for three study periods, each separated by 72 h. The volume of saline was randomized, and a new catheter was inserted for each study period. A standardized dose of 20 mL of 2% plain lidocaine was injected for 10 min, followed by an epidural saline flush 30 min later. Sensory block was assessed by pinprick and transcutaneous electrical stimulation and motor block by a modified Bromage scale and isometric maximal force contraction. Times to void and ambulate independently before discharge were recorded. Peak plasma lidocaine concentrations and time to peak concentration were determined. Results from six volunteers showed that epidural saline, 40 mL, significantly altered anesthetic resolution, accelerating the time of complete sensory and motor block regression (P < 0.05). Median peak levels of sensory and motor block and times to void and ambulate were similar among treatment groups. Peak plasma lidocaine concentrations were similar in all treatment groups. Our data suggest that a 40-mL epidural saline injection 30 min after the induction facilitates regression of epidural lidocaine anesthesia, but a 20-mL bolus does not. Epidural saline injection does not affect vascular absorption of epidural lidocaine. IMPLICATIONS: Epidural catheter flushing with 40 mL of saline, after establishment of epidural lidocaine anesthesia, can facilitate sensory and motor block recovery. However, this does not affect vascular absorption of epidural lidocaine

Christensen L.O., Andersen J.B., Sinkjaer T., and Nielsen J. (2001) Transcranial magnetic stimulation and stretch reflexes in the tibialis anterior muscle during human walking. J. Physiol 531, 545-557.
Abstract: Stretch of the ankle dorsiflexors was applied at different times of the walking cycle in 17 human subjects. When the stretch was applied in the swing phase, only small and variable reflex responses were observed in the active tibialis anterior (TA) muscle. Two of the reflex responses that could be distinguished had latencies which were comparable with the early (M1) and late (M3)components of the three reflex responses (M1, M2 and M3) observed during tonic dorsiflexion in sitting subjects. In the stance phase a single very large response was consistently observed in the inactive TA muscle. The peak of this response had the same latency as the peak of M3, but in the majority of subjects the onset latency was shorter than that of M3. The TA reflex response in the stance phase was abolished by ischaemia of the lower leg at the same time as the soleus H-reflex, suggesting that large muscle afferents were involved in the generation of the response. Motor-evoked potentials (MEPs) elicited in the TA by transcranial magnetic stimulation (TMS) were strongly facilitated corresponding to the peak of the stretch response in the stance phase and the late reflex response in the swing phase. A similar facilitation was not observed corresponding to the earlier responses in the swing phase and the initial part of the response in stance. Prior stretch did not facilitate MEPs evoked by transcranial electrical stimulation in the swing phase of walking. However, in the stance phase MEPs elicited by strong electrical stimulation were facilitated by prior stretch to the same extent as the MEPs evoked by TMS. The large responses to stretch seen in the stance phase are consistent with the idea that stretch reflexes are mainly involved in securing the stability of the supporting leg during walking. It is suggested that a transcortical reflex pathway may be partly involved in the generation of the TA stretch responses during walking

Cikajlo I. and Bajd T. (2000) Use of telekinesthetic feedback in walking assisted by functional electrical stimulation. J. Med. Eng Technol. 24, 14-19.
Abstract: A telekinesthetic feedback implemented into functional electrical stimulation (FES) orthosis is described. Single channel FES is used to provoke ankle dorsiflexion during walking. FES is controlled manually by a special lever, built into the handle of the crutch. The angular position of the lever defines the intensity of stimulation and thus the magnitude of the ankle dorsiflexion. The measured joint angle provides the feedback information about the ankle joint position, which is presented to the user as a force feedback applied to the control lever. As the first step in the development of a complex micromechatronic device, a simulated testing environment was prepared. A computer model, comprising dynamic foot characteristics, as well as agonistic and antagonistic muscle groups, substitutes the ankle joint. The model also includes fatiguing of the electrically stimulated muscles. For experimental purposes an actuated control lever was built. The efficacy of the telekinesthetic feedback was evaluated in a group of six healthy persons

Clippinger F.W., Seaber A.V., McElhaney J.H., Harrelson J.M., and Maxwell G.M. (1982) Afferent sensory feedback for lower extremity prosthesis. Clin. Orthop. 202-206.
Abstract: Electrical stimulation has been applied to sciatic nerves of patients to achieve sensory feedback after lower limb amputation for periods of up to six years. Patients used the sensory feedback device daily. Pain, infection and electrode displacement have not been problems. The immediate postoperative benefits are that pain is minimized after amputation and stump healing is improved. Furthermore, the stimulus affords the patient increased confidence when walking due to renewed awareness of the center of gravity. Improved ability to function in the dark and when walking up and down stairways makes the application of sciatic nerve stimulation after amputation very rewarding

Coburn B. (1984) Paraplegic ambulation: a systems point of view. Int. Rehabil. Med. 6, 19-24.
Abstract: Neurophysiological systems preserved distal to a complete spinal lesion, and relevant to walking, are reviewed in the manner of an engineering control systems analysis. On that basis, an outline is given of theoretical concepts, current developments and future possibilities for neuromuscular electrical stimulation to provide paraplegic ambulation

Dai R., Stein R.B., Andrews B.J., James K.B., and Wieler M. (1996) Application of tilt sensors in functional electrical stimulation. IEEE Trans. Rehabil. Eng 4, 63-72.
Abstract: Tilt sensors, or inclinometers have been investigated for the control of Functional Electrical Stimulation (FES) to improve the gait of persons who had a stroke or incomplete spinal cord injury (SCI). Different types of tilt sensors were studied for their characteristics and their performance in measuring the angular displacement of leg segments during gait. Signal patterns of the lower leg with inertial tilt sensors were identified with control subjects and subjects with footdrop who are being stimulated during level walking. To minimize acceleration responses when the foot swings or hits the ground, we use low-pass filtering (1.5-2 Hz). A finite state approach allows the sensor fixed on the shank to effectively detect the step intention in a population of stroke and incomplete SCI subjects and to control the FES. When the lower leg tilts backward, the common peroneal nerve is stimulated to bring the foot up and forward. We have designed a miniature footdrop stimulator with a magnetoresistive tilt sensor built in, so no external sensor cables are required. The thresholds to turn the stimulator on and off can be adjusted, as well as the maximum period of stimulation and the minimum interval between periods of stimulation. This device features several important advantages over traditional AFO's or stimulators controlled by foot switches. Initial trials with stroke and SCI subjects have demonstrated substantial gait improvement for some subjects, while most liked the good cosmesis and ease of using the device with a tilt sensor

Dalsing M.C., Zukowski A.J., Unthank J.L., Lalka S.G., Sawchuk A.P., and Cikrit D.F. (1994) Details of a canine venous insufficiency model. J. Invest Surg. 7, 85-93.
Abstract: Continued study of a chronic deep venous insufficiency (CDVI) model allows optimal comparison with the human condition. This study evaluates the model's long-term stability, its lack of observed clinical effect, and a simulated exercise study as a physiologic estimate of normal hindlimb walking. The time to maximal ankle venous pressure after standing (VFT), and to 90% of the venous refilling time after electrical stimulation, quadripedal, or hindlimb walking (VRT90), and the minimal pressure after exercise (AVP) were measured up to 10 months after CDVI model creation. The animals' intravenous resting pressure was obtained after standing stationary on all four limbs. Analysis of variance was used to determine statistical significance where indicated. VFT, AVP, and VRT90 measurements demonstrated values consistent with CDVI in animals studied up to 10 months after model creation and were statistically different from control limb values (p < or = .002, n = 8). Animals studied during quadripedal walking showed no difference in resting pressure, AVP, and VRT90 between model and control limbs (n = 5). There was no statistical difference in AVP or VRT90 measured under conditions of stimulated exercise or bipedal walking; and both conditions produced hemodynamic changes consistent with CDVI (n = 5). This animal model is a reliable long-term CDVI hemodynamic model. The normal venous hemodynamics recorded during quadripedic walking may explain the lack of clinical sequelae observed in this model. Lastly, the method of simulated exercise used in this study is a reliable test that reflects physiologic measurements obtained during bipedal walking

Davies C.T. and White M.J. (1982) Muscle weakness following dynamic exercise in humans. J. Appl. Physiol 53, 236-241.
Abstract: Electrical stimulation of the triceps surae in five healthy male subjects showed that following 1-2 h level running and uphill walking, at submaximal voltages of stimulation, exercise enhanced the twitch and tetanic responses, but the supramaximal time to peak tension (TPT), twitch (Pto) and tetanic tensions (Po) at 10 and 20 Hz were reduced by 16 ms (-12.6%), 11 (-8.9%), 163 (-17.5%), and 230 N (-18.1%), respectively. High-frequency (50 and 100 Hz) tetanic stimulation produced qualitatively similar changes to the 20-Hz response, but the stimulus response curve for the two frequencies was different and the ratio of 20- to 50-Hz response (20/50) (cf. Edwards et al., J. Physiol, London 272: 769-778, 1977) was voltage dependent. The reduction in Po at 100 Hz was associated with a decrease in maximal voluntary contraction (MVC). The effects of exercise on Pto and Po at 10, 20, 50, and 100 Hz were short lived and recovered within approximately 2 h. In contrast box-stepping produced a greater fall in Pto and Po at 10 and 20 Hz, which was long lasting (at least (22 h), and there was a consistent fall in the 20/50 ratio. a 2-min "fatigue" test showed that the muscles were weaker but not more fatigable after exercise. Our results seriously question the validity of using submaximal stimulation voltages and ratios for testing human muscle function and suggest that long-lasting muscle weakness is not associated with recovery from prolonged walking, running, and only observed after box-stepping exercise

de Castro M.C. and Cliquet A., Jr. (2000) Artificial sensorimotor integration in spinal cord injured subjects through neuromuscular and electrotactile stimulation. Artif. Organs 24, 710-717.
Abstract: Spinal cord injured (SCI) subjects lack sensorimotor functions. Neuromuscular electrical stimulation (NMES) systems have been used to artificially restore motor functions, but without proprioceptive feedback, SCI subjects can control NMES systems only when they can see their limbs. In a gait restoration system, the subject looks down to the ground to be aware of where his foot is while in a grasping activity, maximum grip strength is employed regardless of the force that is required to perform tasks. This report focuses on artificial sensorimotor integration. Multichannel stimulation was used to restore motor functions while encoded tactile sensation (moving fused phantom images) relating to artificially generated movements was provided by electrotactile stimulation during walking and grasping activities. The results showed that the sensorimotor integration attained yielded both the recognition of artificial grasp force patterns and a technique to be used by paraplegics allowing spatial awareness of their limb while walking

Debreceni L., Gyulai M., Debreceni A., and Szabo K. (1995) Results of transcutaneous electrical stimulation (TES) in cure of lower extremity arterial disease. Angiology 46, 613-618.
Abstract: The results of the treatment of 24 subjects--10 of them diabetic--with peripheral obstructive arterial disease of the lower limbs by transcutaneous electrical stimulation (TES) have been studied. The chronic ischemia of the lower extremities was complicated with ulceration in 12 and initial or advanced gangrene in 6 patients. All patients had been treated with antiplatelet drugs, pentoxifylline, and vasodilating drugs for many years. The drug therapy was continued, and TES was given daily for twenty minutes. The results were estimated after four to eight weeks of hospitalization and during a one-year follow-up in numerous cases. Except for 4 patients the improvement was very significant in all cases: the pain disappeared, the gangrenous process of the toes stopped, regression or complete healing of the ulceration could be observed, and the painfree walking distance increased. The oxygen saturation measured on the toes increased significantly during electrical stimulation. The blood pressure measured in the tibial artery showed very different changes. According to these observations TES appears to be a useful method superior to drug therapy in curing arterial circulatory disturbances of the lower extremities

DiMarco A.F., Romaniuk J.R., Von Euler C., and Yamamoto Y. (1983) Immediate changes in ventilation and respiratory pattern associated with onset and cessation of locomotion in the cat. J. Physiol 343, 1-16.
Abstract: In high decerebrate unanaesthetized cats (pre-collicular/pre-mamillary) which developed spontaneous co-ordinated locomotor activity, ventilation, breathing pattern, phrenic nerve, external and internal intercostal electromyogram (e.m.g.) activities were examined. Locomotion was also induced by electrical stimulation of the subthalamic locomotor region and in a few cases the mesencephalic locomotor region. Quadriceps muscle e.m.g. was used to monitor locomotor activity. Spontaneous locomotor activity was associated with an immediate increase in ventilation and shift of the ventilatory CO2 response curve to the left. Tidal volume was smaller and respiratory rate larger at any given level of ventilation during spontaneous locomotion. Increases in respiratory rate were due to reductions in both inspiratory and expiratory duration. Upon cessation of locomotion, these changes abruptly returned to control values. Within the first one or two walking steps of spontaneous locomotor activity, the rate of rise of phrenic activity increased slightly while peak phrenic activity remained relatively constant; peak internal intercostal activity increased markedly while peak external intercostal activity decreased. Similar changes in ventilation, phrenic, external and internal intercostal activities were observed in association with locomotion induced by stimulation within the subthalamic or mesencephalic locomotor regions. In contrast to spontaneous locomotor activity, however, increases in both external and internal intercostal activities were often observed. Peak amplitudes of both external and internal intercostal activities increased linearly with increasing levels of end- tidal PCO2 during rest and during locomotion. However, at any given level of PCO2 peak external intercostal activity was smaller and peak internal intercostal activity larger during locomotion than at rest. With increasing peak quadriceps e.m.g. activity at a constant walking rate, external intercostal activity was progressively inhibited while internal intercostal activity was progressively enhanced. No consistent change in peak phrenic activity was observed with changes in peak quadriceps activity. With increasing walking rate at a constant peak quadriceps e.m.g., peak phrenic and peak internal intercostal activities progressively increased and peak amplitude of external intercostal activity (which was inhibited below the activity observed at rest) also progressively increased. The virtually simultaneous changes in quadriceps activity and respiratory motor activities suggest that the increase in ventilation at exercise onset is neurally mediated. Furthermore, these results suggest that the motor pathways to both the spinal locomotor pattern generators and the pattern- controlling mechanisms for respiration are driven in parallel to provide a quantitative relationship between respiratory motor output and locomotor activity. The functional significance of the alterations in respiratory pattern and participation of the different respiratory muscles is discussed

Drew T. and Rossignol S. (1987) A kinematic and electromyographic study of cutaneous reflexes evoked from the forelimb of unrestrained walking cats. J. Neurophysiol. 57, 1160-1184.
Abstract: A kinematic and electromyographic (EMG) analysis was undertaken of the responses evoked in the forelimb of the cat by either mechanical obstruction of the forelimb during the swing phase of locomotion or by electrical stimulation of low-threshold cutaneous afferents during both swing and stance. Mechanical obstruction of the forelimb with a stiff metal rod evoked a complex response that allowed the cat to smoothly negotiate the obstacle without undue disruption of the overall locomotor rhythm. The initial movements were a flexion of the shoulder, together with a locking of the elbow joint, and a dorsiflexion of the wrist, which caused the limb to withdraw from the obstacle. They were followed by an extension of the shoulder, a flexion of the elbow, and a ventroflexion of the wrist, which together brought the limb forward and above the obstacle. The associated and complex pattern of s

Duenas S.H., Loeb G.E., and Marks W.B. (1990) Monosynaptic and dorsal root reflexes during locomotion in normal and thalamic cats. J. Neurophysiol. 63, 1467-1476.
Abstract: 1. In normal and thalamic walking cats electrical stimulation of muscle nerves via chronically implanted electrodes produced electromyographic (EMG) and neurographic responses that were modulated in amplitude depending on the phase of the step cycle. These responses were examined for possible indications of effects of primary afferent depolarization (PAD) during stepping. 2. Monosynaptic reflexes (MSRs) produced by stimulating the lateral gastrocnemius (LG) and medial gastrocnemius (MG) nerves were recorded as EMGs in MG or LG muscles during treadmill locomotion in normal cats. These heteronymous MSR responses were greatest during the stance (extensor) phase. 3. In the same animals, after decerebration, similar modulation of the heteronymous ankle extensor MSRs occurred during spontaneous locomotion with the use of the same stimulus and recording sites. 4. In both normal and thalamic cats the amplitude of neurogram responses recorded from LG or MG nerve after stimulation of the other muscle nerve varied with phase of stepping but did not parallel the variations of the MSR measured as EMG amplitude in the same muscle. The nerve responses were largest during the flexion phase of the step cycle and had a calculated central latency of 0.6-1.0 ms. These are interpreted as arising from antidromic activity in large-caliber afferent nerve fibers (i.e., dorsal root reflexes). 5. Spontaneous antidromic activity in severed L7 dorsal rootlet fibers to triceps surae was observed in the thalamic cats during episodes of locomotion and was closely correlated with flexion phase EMG activity in semitendinosus, a bifunctional muscle. 6. In decerebrate cats, dorsal root reflexes (DRRs) in severed filaments of L4-L7 dorsal roots were produced by stimulation of saphenous and posterior tibial nerves. These DRRs were always smaller during locomotion than during rest and were smallest during the flexion phase. 7. The short-latency antidromic activity produced in muscle nerves by stimulating heteronymous muscle nerves thus appears to be a DRR produced in Group I terminal arborizations that are depolarized close to threshold during the flexion phase. Such PAD could account for changes in the MSR that do not always parallel the levels of recruitment of the motor pools as manifest by background EMG amplitude

Duysens J., Tax A.A., Trippel M., and Dietz V. (1992) Phase-dependent reversal of reflexly induced movements during human gait. Exp. Brain Res. 90, 404-414.
Abstract: To investigate whether phase-dependent reversals in reflex responses on electromyography (EMG) are accompanied by movement reversals, a series of human volunteers were studied for their behavioural responses to sural nerve stimulation during running or walking on a treadmill. Low- intensity stimulation (less than 2.5 x perception threshold, T) of the sural nerve yielded facilitatory responses in the tibialis anterior muscle (TA), correlated with an induced ankle dorsiflexion (mean maximum 4 degrees) in early swing. The same stimuli yielded primarily TA suppression and weak ankle plantar flexion (mean maximum 1 degree) at end swing. The correlated induced knee angle changes did not precede the ankle changes, and they were relatively small. Mean maximum flexion in early swing was 6.2 degrees, while mean maximum extension was 3.7 degrees. High-intensity stimulation of the sural nerve (greater than 2.5 x T) always gave rise to suppression of the ongoing activity. This resulted in a second type of movement reversal. During late stance and early swing the responses in TA were suppressive (i.e. below background activity) and related to ankle plantar flexion. In contrast, the responses during early and middle stance consisted of suppression in extensor activity (gastrocnemius medialis and soleus) and ankle dorsiflexion. The data are discussed in terms of a new hypothesis, which states that the responses to electrical stimulation of cutaneous nerves during locomotion do not correspond directly to corrections for stumbling following mechanical perturbations during the step cycle. Instead, the data invite a reinterpretation in terms of the opening and closing of reflex pathways, presumably by a central pattern generator for locomotion

Edrich T., Riener R., and Quintern J. (2000) Analysis of passive elastic joint moments in paraplegics. IEEE Trans. Biomed. Eng 47, 1058-1065.
Abstract: In the functional electrical stimulation of the lower extremity of paraplegics to achieve standing and walking, a mathematical model describing the passive elastic joint moments is essential in order to implement model-based control algorithms. In a previous investigation of ten normal persons we had found significant coupling of passive, elastic joint moments between neighboring joints due to muscle groups that span both joints (biarticular muscles). Thus, we now investigated the biarticular coupling in six paraplegic patients. A comparison to the averaged results of the ten normal persons showed that while the biarticular joint moment coupling due to the gastrocnemius muscle was well preserved in all patients, the coupling due to the rectus femoris was greatly reduced and the coupling due to the hamstring muscle group was negligible. We offer pathophysiologically based explanations for these characteristic differences including the speculation that the predominantly extensor-type spasticity in our patients exercises mainly the anti-gravity muscles such as the gastrocnemius and the rectus femoris, while permitting greater atrophy of the hamstring muscle group. A previously presented double-exponential equation that predicts the joint moments under consideration of the neighboring joint angles could be fitted well to the experimental data

Edwards R.H., Chapman S.J., Newham D.J., and Jones D.A. (1987) Practical analysis of variability of muscle function measurements in Duchenne muscular dystrophy. Muscle Nerve 10, 6-14.
Abstract: To determine the possible sources of variation in performance indicators used in therapeutic trials, electrical stimulation techniques were used to measure contractile properties of the adductor pollicis and quadriceps muscles in boys with Duchenne muscular dystrophy. As no therapeutic effects were observed, longitudinal data obtained are taken to indicate changes in disease progress. Variance in voluntary contractions was found to be similar to that with electrically stimulated contractions; thus, variation could not be attributed to motivational changes, but rather to physiologic changes. Dystrophic muscle was slower to relax and less fatiguable than normal. However, such changes are of less significance to the overall disability compared to the loss of muscle bulk (cross-sectional area). Important variations in the function of individual muscles essential to complex performance, such as walking or getting up from the floor, could be masked by combining results from several muscle groups

Eichhorn K.F., Schubert W., and David E. (1984) Maintenance, training and functional use of denervated muscles. J. Biomed. Eng 6, 205-211.
Abstract: In the case of cerebral paralyses electrical stimulation can not only maintain the muscles, but may also enable their functional use. In flaccid paralyses, however, the conventional therapy using exponential currents produces rather unsatisfactory results. Only when applying bi- directional currents, were we successful in producing tetanic contractions. At present, some 20 children suffering from different diseases, such as spina bifida, Erb's palsy or a tumour of the cord, perform a daily domiciliary treatment with especially constructed home stimulators. Measurements prove distinct improvements of blood circulation, phosphoric metabolism and of the condition of the affected extremities. First investigations with computer-controlled, multi- channel devices show that by means of these devices the efficiency of training can be improved, the daily time for treatment can be shortened, and the disabled patient can perform the training almost autonomously. The existing experience on simple locomotion chains, and the achieved strengthening of the muscles will gradually enable a functional electrical stimulation of flaccid, denerved muscles and thus extend the radius of action for the disabled patient, for example by gripping, standing upright or walking

Eidelberg E., Walden J.G., and Nguyen L.H. (1981) Locomotor control in macaque monkeys. Brain 104, 647-663.
Abstract: We carried out experiments on young adult macaque monkeys (M.fascicularis) in an attempt to establish whether or not primates possess a locomotor control system consisting of spinal pattern generators modulated by brain-stem locomotor regions. We could not induce 'spinal stepping' in our subjects after spinal cord transection. Sparing of pathways contained in the central sector of the white matter of the cord was sufficient for stepping and walking. 'Controlled locomotion' was elicited in thalamic monkeys by electrical stimulation of the posterior subthalamic region or the midbrain tegmentum just ventral to the inferior colliculi. We conclude that there are significant homologies between this primate species and the cat regarding the probable existence of supraspinal locomotor control structures, but it seems that the presumed spinal step generators in monkeys depend more on supraspinal inputs than they do in cats

Endo Y., Tabata T., Kuroda H., Tadano T., Matsushima K., and Watanabe M. (1998) Induction of histidine decarboxylase in skeletal muscle in mice by electrical stimulation, prolonged walking and interleukin-1. J. Physiol 509 ( Pt 2), 587-598.
Abstract: 1. In normal non-exercised skeletal muscles in mice, the activity of histidine decarboxylase (HDC), the enzyme which forms histamine, was very low. 2. HDC activity in the quadriceps femoris muscle was markedly elevated following contractions evoked by even a few minutes of direct electrical stimulation, peaking at 8-12 h following contraction lasting 10 min, and gradually decreasing during the 24 h following contraction. The elevation in HDC activity depended on the duration and strength of stimulation. 3. Direct electrical stimulation induced a quantitatively similar elevation of HDC activity in the muscles of mast-cell-deficient mice (W/Wv mice). 4. Prolonged walking at a speed of 6 m min-1 for up to 6 h with a 30 min rest period at 3 h also elevated muscle HDC activity, the magnitude of the elevation being related to the duration of the walking. Repeated exercise (training) for several days diminished the elevation of muscle HDC activity induced by walking. In contrast, starvation augmented the elevation of muscle HDC activity induced by walking. 5. Intraperitoneal injection of interleukin-1beta (IL-1beta) also elevated muscle HDC activity in a dose-dependent manner, as little as 1 &mgr;g kg-1 of IL-1 producing a significant elevation of muscle HDC activity. 6. IL-1beta was immunohistochemically detected in normal non-exercised quadriceps femoris muscle. We could not detect a significant increase in IL-1beta after exercise in the muscle or in serum: it may be below the level of detection. 7. On the basis of these results, together with those reported previously and the known actions of histamine, we propose that an elevation of HDC activity and generation of histamine occur in skeletal muscle following muscle contraction possibly as a result of induction by IL-1beta and that the histamine may be involved in fatigue in skeletal muscle as part of a defence mechanism preventing damage to the muscle

Fedin A.N. (1980) [Certain functional connections of neurons control the walking of the cockroach Periplaneta americana]. Zh. Evol. Biokhim. Fiziol. 16, 454-460.
Abstract: On isolated abdominal nervous chain of the cockroach studies have been made of the responses of motoneurones of the thoracic ganglion to electrical stimulation of afferent axons of the leg nerve under normal conditions and during application of an anticholinesterase drug, GD-7. Depending on the type of stimulated axons, monosynaptic response, as well as polysynaptic phasic and tonic responses of motoneurones were recorded. A scheme of activation of motoneurones is suggested which evokes slow contractions of muscles in cockroach extremities

Ferguson K.A., Polando G., Kobetic R., Triolo R.J., and Marsolais E.B. (1999) Walking with a hybrid orthosis system. Spinal Cord. 37, 800-804.
Abstract: OBJECTIVE: The purpose of this case study was to determine the functional effectiveness of the hybrid orthosis system (HOS) for sit-to- stand and walking compared with the reciprocal gait orthosis (RGO) alone in a subject with significant orthopedic abnormalities. DESIGN: A subject with complete T7 paraplegia and a 13 cm leg length discrepancy was implanted with 14 intramuscular electrodes and fitted with a custom isocentric RGO. The subject was instructed in the use of the HOS and a two wheeled walker in the home and community settings. MAIN OUTCOME MEASURES: Using the Functional Independence Measure (FIM), and the Borg exertion scale the subject's level of independence and his perceived exertion was determined as well as the safety and efficacy of system use in the community. RESULTS: Results show that the HOS provided safe, independent ambulation with a two wheeled walker and met established criteria for limited community use. Walking in the RGO alone was feasible, however, the addition of functional electrical stimulation (FES) allowed this subject to walk farther and with less perceived exertion. CONCLUSION: This case study suggests that a hybrid orthosis system can be an effective clinical option for individuals with significant orthopedic complications that might otherwise contra- indicate the prescription of either conventional braces or FES alone

Field-Fote E.C. (2000) Spinal cord control of movement: implications for locomotor rehabilitation following spinal cord injury. Phys. Ther. 80, 477-484.
Abstract: In recent years, our understanding of the spinal cord's role in movement control has been greatly advanced. Research suggests that body weight support (BWS) walking and functional electrical stimulation (FES), techniques that are used by physical therapists, have potential to improve walking function in individuals with spinal cord injury (SCI), perhaps long after the stage of spontaneous recovery. Walking is one of the most desired goals of people with SCI; however, we are obligated to be judicious in our claims of locomotor recovery. There are few controlled studies that compare outcomes of BWS training or FES with those of conventional interventions, and access to services using BWS training or FES may be restricted under managed care

Fredriksen T.A., Bergmann S., Hesselberg J.P., Stolt-Nielsen A., Ringkjob R., and Sjaastad O. (1986) Electrical stimulation in multiple sclerosis. Comparison of transcutaneous electrical stimulation and epidural spinal cord stimulation. Appl. Neurophysiol. 49, 4-24.
Abstract: Forty-nine multiple sclerosis patients with bladder symptoms and/or walking disability were subjected to a therapeutic trial with electrical spinal cord stimulation and transcutaneous electrical stimulation, a second aim being to compare these two treatments. A clear subjective improvement in bladder symptoms was achieved in the majority of the cases, and this was substantiated by objective parameters. In a proportion of cases a more moderate improvement seems to have been achieved in a variety of symptoms. Transcutaneous electrical stimulation seems to be a useful selection procedure for later electrical spinal cord stimulation

Friedman R.N. and Si K. (1999) Initial characterization of the effects of Aloe vera at a crayfish neuromuscular junction. Phytother. Res. 13, 580-583.
Abstract: This study examines the effects of Aloe vera on neurotransmission processes in a well-established invertebrate neuromuscular junction preparation. We studied concentration-response relationships of an Aloe vera extract on excitatory junctional potentials (EJPs) at the opener muscle of the dactyl in the first and second walking limbs of crayfish (Procambarus clarkii and simulans). We observed concentration-dependent depolarizations of the muscle fibre membrane resting potential, depression of EJP amplitudes and an increase in latency to onset of the EJP following electrical stimulation of the isolated excitatory axon in the meropodite. These effects occurred with Aloe concentrations within the 1%-10% (wt-vol) range. Effects of lower concentrations, ranging to a minimum of 0.01% were equivocal. The effects of Aloe were at least partially, and in a majority of cases totally, reversible. EJPs reduced by Aloe could be restored by increasing the nerve stimulation amplitude. This, along with the latency increase, suggests a depression of action potential generation and conduction. The results provide a preliminary characterization of the effects of Aloe vera on the neurotransmission process and suggest that these effects may at least partially account for Aloe's analgesic and antiinflammatory effects. This study shows that the crayfish NMJ preparation should be useful for further elucidating the location(s) and mechanism(s) of action of Aloe on the nervous system

Fung J. and Barbeau H. (1994) Effects of conditioning cutaneomuscular stimulation on the soleus H- reflex in normal and spastic paretic subjects during walking and standing. J. Neurophysiol. 72, 2090-2104.
Abstract: 1. The modulation of the soleus H-reflex by a conditioning cutaneomuscular stimulation was investigated in 10 normal and 10 spastic paretic subjects who suffered from incomplete spinal cord lesions. The different motor tasks examined were standing, locomotion, and the maintenance of static limb postures to mimic critical gait events. The test soleus H-reflex was obtained by stimulating the tibial nerve in the popliteal fossa with a single 1-ms pulse at an intensity that produced a barely detectable M wave. The conditioning stimulus, consisting of an 11-ms train of three 1-ms pulses at 200 Hz, was delivered to the ipsilateral medial plantar arch, stimulating predominantly the medial plantar nerve, at an innocuous intensity of 2.5-3.0 X sensory threshold and at a conditioning-test delay of 45 ms. 2. During quiet standing, the H-reflex amplitude was inhibited only marginally by the conditioning cutaneomuscular stimulation, not reaching statistical significance in either the normal or spastic group of subjects. Although there was a trend of reflex inhibition in the normal subjects as the conditioning intensity was increased, a reversed trend of reflex facilitation was observed in the spastic patients. 3. During treadmill walking, the conditioned H-reflex was inhibited significantly during all phases in all the normal subjects and in one mildly impaired patient. In the moderately and severely impaired patients, cutaneomuscular stimulation selectively inhibited the soleus H-reflex in the early stance and swing phases, thereby producing a near normal phasic modulation pattern. Such modulatory effects were not present under static gait-mimicking conditions. 4. The task-specific and phase-dependent effects of cutaneomuscular stimulation on the soleus H-reflex in the spinal cord-injured patients revealed strong inhibitory influence on Ia afferents from cutaneomuscular inputs. It is plausible that inhibition occurs at both pre- and postsynaptic levels. 5. It is concluded that normal Ia modulatory mechanisms during locomotion are deficient in spastic spinal cord-injured patients and can partially and artificially be restored by cutaneomuscular stimulation applied to the sole of the foot. This can be used as a functional electrical stimulation (FES) regime in gait rehabilitation

Gallien P., Brissot R., Eyssette M., Tell L., Barat M., Wiart L., and Petit H. (1995) Restoration of gait by functional electrical stimulation for spinal cord injured patients. Paraplegia 33, 660-664.
Abstract: In this clinical study, we report the results of functional electrical stimulation for the ambulation of paraplegic patients without long leg braces (LLB), according to the Parastep approach. Of 13 SCI patients with complete neurological lesions included in this trial, 12 progressed to independent ambulation with the aid of the Parastep. The average walking distance was 76 m, with a maximum of 350 m, and the mean speed 0.2 m s-1. Compared to the situation with long leg braces, which in fact are given up by most paraplegic patients, long term home use seems to be much more important. Tolerance of this method is satisfactory. The psychological benefits of the device are remarkable. From this experience, it is concluded that this method is valuable for the restoration of standing and walking in the long term management of spinal cord injury patients

Garcia-Rill E., Skinner R.D., and Fitzgerald J.A. (1985) Chemical activation of the mesencephalic locomotor region. Brain Res. 330, 43-54.
Abstract: Electrical stimulation of the mesencephalic locomotor region (MLR) in the precollicular-postmammillary transected cat is known to induce controlled locomotion on a treadmill. We have been able to induce and block locomotion in this preparation by using localized infusions of transmitters and their agonists and antagonists. Infusions of the GABA antagonists bicuculline and picrotoxin into the MLR elicit locomotion at low concentration (5 mM). Applications of muscimol (5 mM) or GABA (0.5 M) were found to block chemically-induced locomotion, as well as electrically-elicited and spontaneous walking. Priming infusions of Diazepam amplified the blockage of locomotion by GABA. On the other hand, applications of strychnine (10 mM) were ineffective in inducing stepping, as were infusions of the excitatory agents glutamic acid, acetylcholine and norepinephrine. These findings suggest that the MLR is under inhibitory GABAergic input. The substantia nigra is the only known afferent to the MLR located posterior to the brainstem transection, and is a likely source for this input. A model is proposed to account for our results, as well as those of others, and it provides a working hypothesis for the neurochemical events occurring in brainstem centers which modulate locomotor events

Gaviria M. and Ohanna F. (1999) Variability of the fatigue response of paralyzed skeletal muscle in relation to the time after spinal cord injury: mechanical and electrophysiological characteristics. Eur. J. Appl. Physiol Occup. Physiol 80, 145-153.
Abstract: The aim of this study was to determine the effect of the time after spinal cord injury (less than and greater than 10 months) on the mechanical and electrophysiological characteristics of muscle fatigue of the paralyzed electrically stimulated quadriceps muscle. Morphologically and histochemically, a relationship was observed between muscle fatigue and the delay from injury, revealing a critical period of enzymatic turning and a maximum peak of atrophy around the 10th month after the injury, followed by a long-term stabilization. Knee-torque output and M-wave variables (amplitude, latency, duration, and root mean square, RMS) of two muscular heads of the quadriceps were recorded in 19 paraplegic patients during a 120-s isometric contraction. The fatiguing muscle contraction was elicited by supramaximal continuous 20-Hz electrical stimulation. Compared to the chronic group, the acutely paralyzed group showed a greater resistance to fatigue (amount and rate of force decline, P < or = 0.01), smaller alterations of the M-wave amplitude and RMS, and a limited decrease of the muscle fiber conduction velocity (P < 0.05). Mechanical and electrophysiological changes during fatigue provided a clear functional support of the transformation of skeletal muscle under the lesion and of the existence of a critical period of muscular turn. In conclusion, when considering the artificial restoration of motor function, the evolution of the endurance and force-generating capabilities of the muscle actuator must be taken into account, particularly when tasks require important safety conditions (e.g., standing and walking)

Godec C.J. and Cass A.S. (1980) Cystometric variations during postural changes and functional electrical stimulation of the pelvic floor muscles. J. Urol. 123, 722-725.
Abstract: Postural changes did not affect the cystometric curves of bladder function that were hyperreflexic, flaccid or secondary to bladder wall changes (fibrosis and inflammation). However, postural changes did affect normal curves in some patients with a history of micsturition disorders and resulted in detrusor instability when the patient was standing or walking. Functional electrical stimulation of the pelvic floor muscles during the cystometrogram inhibited detrusor instability of these patients in all positions. Use of postural changes and functional electrical stimulation of the pelvic floor muscles during the cystometrogram inhibited detrusor instability of these patients in all positions. Use of postural changes and functional electrical stimulation of the pelvic floor muscles is suggested to determine actual bladder function and to exclude possible artifacts in the curve

Granat M., Keating J.F., Smith A.C., Delargy M., and Andrews B.J. (1992) The use of functional electrical stimulation to assist gait in patients with incomplete spinal cord injury. Disabil. Rehabil. 14, 93-97.
Abstract: The use of FES (functional electrical stimulation) for gait reproduction in six patients with spinal cord injury is described. Following a detailed neuromuscular assessment the patients commenced a muscle conditioning programme using electrical stimulation applied via surface electrodes. Once patients were strong enough to stand, gait synthesis was initiated in the laboratory utilizing a programmable electrical stimulator. When a satisfactory gait pattern had been achieved, patients used their portable stimulator at home. All six patients became able to stand and walk using the FES system and completed the home phase of the programme. Three patients continue to use the system at home for exercise and walking; the other patients have discontinued using the system, preferring a wheelchair or their original orthoses. We conclude that FES-assisted walking is feasible in patients with incomplete spinal cord injury, even with severe motor loss. Further advances in technology are needed for the system to become applicable to a larger number of patients

Graupe D., Kohn K.H., Kralj A., and Basseas S. (1983) Patient controlled electrical stimulation via EMG signature discrimination for providing certain paraplegics with primitive walking functions. J. Biomed. Eng 5, 220-226.

Graupe D. and Kohn K.H. (1987) A critical review of EMG-controlled electrical stimulation in paraplegics. Crit Rev. Biomed. Eng 15, 187-210.
Abstract: This review presents a description and provides a comparative performance evaluation of EMG control vs. other approaches to controlling functional electrical stimulation (FES) in upper-motor- neuron paraplegics to provide them with a certain degree of walking ability with walker support. EMG control is considered in terms of a combination of above-lesion EMG control and below-lesion response-EMG control. The above-lesion EMG is to control the activation of different limb functions involved in standing up and walking via FES. This control is accomplished by analyzing raw surface EMG time-series patterns to discriminate between upper-trunk muscle contraction patterns which, in turn, are correlated with intended lower-limb functions involved in walking, so that natural and instinctive balance changes of paraplegics are reflected and controlled by the patient only above the lesion. The below-lesion response-EMG is the EMG produced in response to the FES pulses at the stimulation sites, for adjusting stimulation levels as needed when contractions weaken due to muscle fatigue. Above-lesion EMG is a stochastic (random-like) signal, being a response to unsynchronized motor-neuron firings, whereas the below- lesion EMG is a deterministic signal responding to synchronized firings that result solely from the FES pulses. The present review discusses the merits and difficulties of EMG control and attempts to give a critical evaluation of patient performance under such control, contrasted to other methods of control, noting that FES-activated walking without adequate and patient-responsive control is of very limited attraction and use to paraplegics. Of the various control methods, only

Graupe D., Kohn K.H., and Basseas S. (1988) A. J. Biomed. Eng 10, 305-311.
Abstract: We describe and evaluate a

Graupe D. (1989) EMG pattern analysis for patient-responsive control of FES in paraplegics for walker-supported walking. IEEE Trans. Biomed. Eng 36, 711-719.
Abstract: This paper describes and discusses the employment of EMG pattern analysis to provide upper-motor-neuron paraplegics with patient- responsive control of FES (functional electrical stimulation) for the purpose of walker-supported walking. The system described employs above- lesion surface EMG signals to activate standing and walking functions in a patient-responsive manner. This system has been experimentally applied to paraplegics at Michael Reese Hospital and Medical Center in Chicago since early 1982. Below-lesion response-EMG control from the stimulated sites has been added in 1987 to regulate stimuli levels in the face of fatigue. Although transcutaneous FES alone is being employed, the system is applicable in principle also to implantable FES systems

Graupe D. and Kordylewski H. (1995) Artificial neural network control of FES in paraplegics for patient responsive ambulation. IEEE Trans. Biomed. Eng 42, 699-707.
Abstract: This paper describes an ART-1-based artificial neural network (ANN) adapted for controlling functional electrical stimulation (FES) to facilitate patient-responsive ambulation by paralyzed patients with spinal cord injuries. This network is to serve as a controller in an FES system developed by the first author which is presently in use by 300 patients worldwide (still without ANN control) and which was the first and the only FES system approved by the FDA. The proposed neural network discriminates above-lesion upper-trunk electromyographic (EMG) time series to activate standing and walking functions under FES and controls FES stimuli levels using response-EMG signals. For this particular application, we introduce several modifications of the binary adaptive resonance theory (ART-1) for pattern recognition and classification. First, a modified on-line learning rule is proposed. The new rule assures bidirectional modification of the stored patterns and prevents noise interference. Second, a new reset rule is proposed which prevents "exact matching" when the input is a subset of the chosen pattern. We show the applicability of a single ART-1-based structure to solving two problems, namely, 1) signal pattern recognition and classification, and 2) control. This also facilitates ambulation of paraplegics under FES, with adequate patient interaction in initial system training, retraining the network when needed, and in allowing patient's manual override in the case of error, where any manual override serves as a retraining input to the neural network. Thus, the practical control problems (arising in actual independent patient ambulation via FES) were all satisfied by a relatively simple ANN design

Graupe D. and Kohn K.H. (1998) Functional neuromuscular stimulator for short-distance ambulation by certain thoracic-level spinal-cord-injured paraplegics. Surg. Neurol. 50, 202-207.
Abstract: BACKGROUND: Functional Neuromuscular Stimulation (FNS) for unbraced short-distance ambulation by traumatic complete/near-complete T4 to T12 paraplegics is based on work by Graupe et al (1982), Kralj et al (1980), Liberson et al (1961), and others. This paper discusses methodology, performance, training, admissibility criteria, and medical observations for FNS-ambulation using the Parastep-I system, which is the first and only such system to have received FDA approval (1994) and which emanated from these previous works. METHOD: The Parastep system is a transcutaneous non-invasive and microcomputerized electrical stimulation system built into a Walkman-size unit powered by eight AA batteries that is controlled by finger-touch buttons located on a walker's handbars for manual selection of stimulation menus. The microcomputer shapes, controls, and distributes trains of stimulation signals that trigger action potentials in selected peripheral nerves. Walker support is used for balance. The patient can don the system in under 10 minutes. At least 32 training sessions are required. RESULTS: Approximately 400 patients have used the Parastep system, essentially all achieving standing and at least 30 feet of ambulation, with a few reaching as much as 1 mile at a time. Recent literature presents data on the medical benefits of using the Parastep system-beyond the exercise benefits of short distance ambulation at will-such as increased blood flow to the lower extremities, lower HR at subpeak work intensities, increased peak work capability, reduced spasticity, and psychological benefits. CONCLUSIONS: We believe that the Parastep FNS system, which is presently commercially available by prescription, is easily usable for independent short-distance ambulation. We believe that its exercise benefits and its other medical and psychological benefits, as discussed, make it an important option for thoracic-level traumatic paraplegics

Graupe D., Suliga P., Prudian C., and Kohn K.H. (2000) Stochastically-modulated stimulation to slow down muscle fatigue at stimulated sites in paraplegics using functional electrical stimulation for leg extension. Neurol. Res. 22, 703-704.
Abstract: This short communication is a preliminary report on a study concerning slowing down the rate of muscle fatigue when FES (Functional Electrical Stimulation) is applied for standing and walking by complete (traumatic) thoracic-level paraplegics. It is shown that randomly modulating the inter-pulse interval between FES pulses (which serve to trigger action potentials in the peripheral nerves concerned) results in a significantly lower rate of muscle fatigue, as tested in a series of leg extensions, when FES was applied at the quadriceps. Specifically, we report that the best results (longest durations of leg extension prior to onset of muscle-fatigue) were achieved with a +/- 5 msec uniformly-distributed (pseudo-) white-noise modulation at a 42 msec inter-pulse interval (24 pulses per sec). These resulted in an average increase in duration of leg extension of approximately 37% in this pilot study, as compared with unmodulated (fixed-rate) trains of FES pulses. This significant increase, even in a very preliminary study appears to merit careful further examination, since it may allow a possibly significant increase in standing duration and in walking range of paraplegics using FES for ambulation

Green E.J., Barnes C.A., and McNaughton B.L. (1993) Behavioral state dependence of. Exp. Brain Res. 93, 55-65.
Abstract: The effects of two different waking behavioral states on the modulation of perforant, path-evoked population spikes were studied following prestimulation of either the perforant path itself, the dentate gyrus commissural/association pathway, or the medial septum. The intermediate- latency, post-inhibitory 'rebound' of the population spike, which normally follows short-latency, perforant path or commissure-induced inhibition, was substantially increased during forced locomotion on a treadmill, compared with quiet wakefulness. There was no effect of these behavioral states either on the short-latency inhibitory phase itself or on the average magnitude of the unconditioned population spike. The short-latency, GABA-mediated disinhibitory effect of medial septal prestimulation was slightly reduced by walking, as might be expected from the increased feedforward excitatory drive on hippocampal interneurons that occurs during walking. Septal prestimulation during walking also led to a large, intermediate-latency spike facilitation that was completely absent during the quiet, awake state. Lesions of the medial septum attenuated the effects of behavioral state on the post-inhibitory facilitation from both perforant path and commissural stimulation. Atropine reduced the walking-induced increase in intermediate-latency facilitation, but had no effect in the still condition. We conclude that, during walking, electrical stimulation within the hippocampal formation or septum leads to a delayed increase in dentate gyrus excitability that is probably mediated polysynaptically through the medial septum or fibers passing through it. This state dependency is not due to tonic suppression of the inhibitory systems within the dentate gyrus itself

Greve J.M., Muskat R., Chiovatto J., Ogawa C.T., Battistella L.R., and Barros Filho T.E. (1992) [Functional electrical stimulation in the reciprocal locomotion of paraplegic patients]. Rev. Hosp. Clin. Fac. Med. Sao Paulo 47, 138-141.
Abstract: The functional electrical stimulations is employed for standing-up posture and reciprocal locomotion in paraplegic patients. Five male paraplegic patients, level D5-D12 mean age 32.4 years, were treated with functional electrical stimulation, during two months. The quadriceps and fibular nerves were stimulated for 30 minutes, twice a day. After the training period, two patients were able to remain in the stand-up position and walk in parallel bars; one of them was able to use a walker. In other patients the technique was without effect for standing and walking. This method is not the solution for locomotion of paraplegics and more research is needed for the improvement of the results of functional electrical stimulation

Grossiord A. and Maury M. (1979) [The possibility of walking in the paralysed of the lower limbs (author's transl)]. Rev. Chir Orthop. Reparatrice Appar. Mot. 65, 305-310.
Abstract: The authors have studied the possibility of walking after rehabilitation and bracing in the paralysed of the lower limbs, it is variable with aetiological factors and age of patients. In children, walking after bracing is almost always indicated-it should be discussed case after case in adults. The authors analyse the role of different types of braces such as pneumatic braces and orthoptic systems using electrical stimulation. Some views on the future are exposed

Guest R.S., Klose K.J., Needham-Shropshire B.M., and Jacobs P.L. (1997) Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 4. Effect on physical self- concept and depression. Arch. Phys. Med. Rehabil. 78, 804-807.
Abstract: OBJECTIVE: To determine whether persons with spinal cord injury (SCI) paraplegia who participated in an electrical stimulation walking program experienced changes in measures of physical self-concept and depression. DESIGN: Before-after trial. SETTING: Human SCI applied research laboratory. PARTICIPANTS: Volunteer sample of 12 men and 3 women with SCI paraplegia, mean age 28.75 +/- 6.6yrs and mean duration of injury 3.8 +/- 3.2yrs. INTERVENTION: Thirty-two FNS ambulation training sessions using a commercially available system (Parastep 1). The hybrid system consists of a microprocessor-controlled stimulator and a modified walking frame with finger-operated switches that permit the user to control the stimulation parameters and activate the stepping. OUTCOME MEASURES: The Tennessee Self-Concept Scale (TSCS) and the Beck Depression Inventory (BDI) were administered before and after training. Only the Physical Self subscale of the TSCS was analyzed. After training, individual interviews were performed to assess participants' subjective reactions to the training program. RESULTS: A repeated measures analysis of variance indicated that desired directional and statistically significant changes occurred on the Physical Self subscale of the TSCS (F(1,14) = 8.54, p < .011) and on the BDI (F(1,14) = 5.42, p < .035). CONCLUSIONS: Subsequent to the ambulation training program there were statistically significant increases in physical self-concept scores and decreases in depression scores

Haugland M. and Sinkjaer T. (1999) Interfacing the body's own sensing receptors into neural prosthesis devices. Technol. Health Care 7, 393-399.
Abstract: Functional Electric Stimulation (FES) is today available as a tool in muscle activation used in picking up objects, in standing and walking, in controlling bladder emptying, and for breathing. Despite substantial progress over nearly three decades of development, many challenges remain to provide a more efficient functionality of FES systems. The most important of these is an improved control of the activated muscles. Instead of artificial sensors for feedback, new developments in electrodes to do long-term and reliable recordings from peripheral nerves emphasize the use of the body's own sensors. These are already installed and optimised through millions of years of natural evolution. This paper presents recent results on a system using electrical stimulation of motor nerves to produce movement and using the natural sensors as feedback signals to control the stimulation that can replicate some of the functions of the spinal cord and its communication with the brain. We have used the nerve signal recorded from cutaneous nerves in two different human applications: (1) to replace the external heel switch of a system for correction of spastic drop foot by peroneal stimulation, and (2) to provide an FES system for restoration of hand grasp with sensory feedback from the fingertip. For the bladder function, the sacral root stimulator is a useful control tool in emptying the bladder. To decide when to stimulate, we are at present carrying out experiments on pigs and cats using cuff electrodes on the pelvic nerve and sacral roots to record the neural information from bladder afferents. This information can potentially be used to inhibit unwanted bladder contractions and to trigger the FES system and thereby bladder emptying. Future research will show whether cuffs and other types of electrodes can be used to reliably extract signals from the large number of other receptors in the body to improve and expand on the use of natural sensors in clinical FES systems

Hazlewood M.E., Brown J.K., Rowe P.J., and Salter P.M. (1994) The use of therapeutic electrical stimulation in the treatment of hemiplegic cerebral palsy. Dev. Med. Child Neurol. 36, 661-673.
Abstract: The effect of electrical stimulation of the anterior tibial muscles of children with hemiplegic cerebral palsy was studied. 10 children received electrical stimulation, applied by their parents daily for an hour for 35 days; they were compared with 10 matched controls. Active and passive ranges of movement of the ankle, and knee and ankle motion during walking were measured before and after therapy using electrogoniometers. The results showed a significant increase in passive range of movement among children receiving electrical stimulation. Gait analysis of knee and ankle motion showed little change

Hesse S., Malezic M., Schaffrin A., and Mauritz K.H. (1995) Restoration of gait by combined treadmill training and multichannel electrical stimulation in non-ambulatory hemiparetic patients. Scand. J. Rehabil. Med. 27, 199-204.
Abstract: Functional electrical stimulation and treadmill training with partial body weight support through suspension by a parachute harness were combined for gait restoration in 11 chronic non-ambulatory hemiparetic patients. Individually adjusted multichannel stimulation of the trunk and of upper and lower limb muscles, as well as a motor driven treadmill, induced functional gait within 3 to 6 weeks. The improvement of gait ability was assessed by the Functional Ambulation Category test. Other motor functions were rated by the Rivermead Motor Score. The leg muscle strength, stride length, cadence, gait velocity and gait pattern were recorded. In seven of the patients, we did a single case research A-B-A study that showed that this combined approach had advantages, in regard to gait restoration and walking velocity (p ]0.05) as compared with our common physiotherapeutic programme

Hesse S., Jahnke M.T., Luecke D., and Mauritz K.H. (1995) Short-term electrical stimulation enhances the effectiveness of Botulinum toxin in the treatment of lower limb spasticity in hemiparetic patients. Neurosci. Lett. 201, 37-40.
Abstract: The study tested the spasmolytic effect of Botulinum toxin A in two groups of hemiparetic patients with lower limb spasticity: in the first group (n = 5) 2000 U Dysport were injected into the soleus, tibialis posterior and both heads of gastrocnemius muscles alone; the second (n = 5) received additional repetitive alternating electrical stimulation of M. tibialis anterior and plantar flexors for 30 min six times per day during the 3 days following the injection. Muscle tone, rated by the Ashworth spasticity score, and gait analysis including recording of vertical ground reaction forces, were assessed before and 4 weeks after injection. The combined treatment proved to be more effective with respect to the clinically assessed reduction of muscle tone, gait velocity, stride length, st

Hesse S., Malezic M., Lucke D., and Mauritz K.H. (1998) [Value of functional electrostimulation in patients with paraplegia]. Nervenarzt 69, 300-305.
Abstract: This 1-year follow-up study included 17 patients with spinal cord injuries who participated in a functional electrical stimulation (FES) program for restoration of the ability to stand and walk. Four tetraplegic patients reached a mean FES-assisted standing duration of 6.8 min after 6 weeks. After 1 year three patients had stopped FES- assisted standing due to orthostatic problems and only used the system for cyclic stimulation of quadriceps muscles while lying down. Ten paraplegic patients had a mean standing duration of 22.6 min. The gait velocity (gait distance) of seven patients ranged from 2.9 to 24.2 m/min (from 4 to 335 m) in seven patients. Due to flexor spasm in two and unrealistic expectations in seven cases, four patients stopped the program and five only practiced FES-assisted standing. One patient continued FES walking after 1 year. Three patients with an incomplete cervical lesion who had been able to walk a short distance before treatment achieved constant improvement their gait ability. Their gait velocity/walking distance without FES improved for a mean of +33.3%/+163.8%, after 6 weeks. Assuming that FES is used according to the level of impairment, the results favor broader application of the method in the rehabilitation of patients with spinal cord injuries

Hesse S., Brandi-Hesse B., Bardeleben A., Werner C., and Funk M. (2001) Botulinum toxin A treatment of adult upper and lower limb spasticity. Drugs Aging 18, 255-262.
Abstract: This article discusses the treatment of spasticity with botulinum toxin A as a new approach in the neurological rehabilitation of patients after stroke. Clinical studies have been reviewed to provide information about target groups, technical aspects and the advantages and disadvantages of treating spasticity with botulinum toxin A. Open and controlled studies showed that the intramuscular injection of Dysport 500 to 1,500U or Botox 100 to 300U could reversibly relieve upper limb flexor and lower limb extensor spasticity. A reduced muscle tone, pain relief, better hand hygiene and improved walking function were the main benefits. Patients tolerated the treatment well. Activity or, if not possible, electrical stimulation of the injected muscles may enhance the effectiveness of the costly toxin. Serial casting is another option. With respect to the action of botulinum toxin A, it is suggested that the effect of the toxin could be mediated by paresis of both the extrafusal and intrafusal muscle fibres, thereby altering the afferent discharge in the muscle

Hiebert G.W., Whelan P.J., Prochazka A., and Pearson K.G. (1996) Contribution of hind limb flexor muscle afferents to the timing of phase transitions in the cat step cycle. J. Neurophysiol. 75, 1126-1137.
Abstract: 1. In this investigation, we tested the hypothesis that muscle spindle afferents signaling the length of hind-leg flexor muscles are involved in terminating extensor activity and initiating flexion during walking. The hip flexor muscle iliopsoas (IP) and the ankle flexors tibialis anterior (TA) and extensor digitorum longus (EDL) were stretched or vibrated at various phases of the step cycle in spontaneously walking decerebrate cats. Changes in electromyogram amplitude, duration, and timing were then examined. The effects of electrically stimulating group I and II afferents in the nerves to TA and EDL also were examined. 2. Stretch of the individual flexor muscles (IP, TA, or EDL) during the stance phase reduced the duration of extensor activity and promoted the onset of flexor burst activity. The contralateral step cycle also was affected by the stretch, the duration of flexor activity being shortened and extensor activity occurring earlier. Therefore, stretch of the flexor muscles during the stance phase reset the locomotor rhythm to flexion ipsilaterally and extension contralaterally. 3. Results of electrically stimulating the afferents from the TA and EDL muscles suggested that different groups of afferents were responsible for the resetting of the step cycle. Stimulation of the TA nerve reset the locomotor step cycle when the stimulus intensity was in the group II range (2-5 xT). By contrast, stimulation of the EDL nerve generated strong resetting of the step cycle in the range of 1.2-1.4 xT, where primarily the group Ia afferents from the muscle spindles would be activated. 4. Vibration of IP or EDL during stance reduced the duration of the extensor activity by similar amounts to that produced by muscle stretch or by electrical stimulation of EDL at group Ia strengths. This suggests that the group Ia afferents from IP and EDL are capable of resetting the locomotor pattern generator. Vibration of TA did not affect the locomotor rhythm. 5. Stretch of IP or electrical stimulation of TA afferents (5 xT) during the flexion phase did not change the duration of the flexor activity. Stimulation of the EDL nerve at 1.8-5 xT during flexion increased the duration of the flexor activity. In none of our preparations did we observe resetting to extension when the flexor afferents were activated during flexion. 6. We conclude that as the flexor muscles lengthen during the stance phase of gait, their spindle afferents (group Ia afferents for EDL and IP, group II afferents for TA) act to inhibit the spinal center generating extensor activity thus facilitating the initiation of swing

Hirokawa S., Solomonow M., Baratta R., and D'Ambrosia R. (1996) Energy expenditure and fatiguability in paraplegic ambulation using reciprocating gait orthosis and electric stimulation. Disabil. Rehabil. 18, 115-122.
Abstract: To clarify the relationship between metabolic energy expenditure and fatiguability in paraplegic persons fitted with orthoses, we measured energy consumption in six thoracic paraplegic patients ambulating by means of reciprocating gait orthosis (RGO) used with and without functional electrical stimulation (FES). The data obtained from persons using both RGO and FES were adjusted to allow for the effects of fatiguability so as to obtain an approximate value for upper-body consumption. The data obtained from persons using RGO only were not adjusted, because no energy consumption occurred in the lower portion of the body. The data, expressed in kcal/kg-min and kcal/kg-m, were plotted against walking speed attained using RGO, and RGO with FES. The results were compared with those from persons fitted with long leg braces (LLB), hip guidance orthoses (HGO) and an FES walking aid (data obtained from available literature). We found that the lowest energy expenditure in kcal/kg-m across the full range of walking speeds occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only, respectively. The lowest energy expenditure in kcal/kg-min, for walking speeds, below 0-28 m/s, also occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only. The results suggest that, although the use of FES with RGO may increase oxygen uptake, it decreases energy expenditure in the upper extremities, thereby reducing patient fatigue. They also suggest that mechanical orthosis giving passive support to the hip, knee and ankle in combination with FES may provide the most efficient walking aid for paraplegic persons

Hunter P.P. (1992) Opportunities and challenges for the clinical utilization of functional electrical stimulation. Assist. Technol. 4, 46-48.
Abstract: Clinical applications of electrical stimulation for effecting change in the damaged or disabled nervous system are in their infancy. This technique is extremely powerful, because any neural structure that is electrically excitable can potentially be affected. Although early attempts to apply electrical stimulation were limited by insufficient physiological knowledge and undeveloped technology, developments over the past two decades now provide a strong base for clinical applications. Clinical systems for bladder control and respiration have been in use for many years. Some applications of FES to restore hand function and walking are in multicenter testing, whereas many others are being studied for clinical feasibility at single sites. Applications are focusing on safety and efficacy, as well as on clinical outcome measures to address the issues posed by the regulatory and reimbursement processes. As clinical systems become more routine, issues of multiple system applications will need to be addressed. Present and future applications of functional electrical stimulation may be expected to significantly enhance independence and improve the quality of life for individuals with central nervous system dysfunction

Isakov E., Mizrahi J., Graupe D., Becker E., and Najenson T. (1985) Energy cost and physiological reactions to effort during activation of paraplegics by functional electrical stimulation. Scand. J. Rehabil. Med. Suppl 12, 102-107.
Abstract: In this study, the aim was to evaluate the influence on the cardiopulmonary system of muscular contractions of the paralyzed limbs in paraplegia, activated by FES during treatment, and the energy cost of standing and walking while using FES as an orthotic aid. Three traumatic spastic paraplegics were selected for the measurements. At the end of a 6 month training program heart rate and oxygen consumption of the patients were evaluated as follows: at rest; following 30 minutes of FES in the sitting position; following 15 minutes of standing; and during ambulation. Lactic acid level during maximal effort was evaluated as well. The results indicated a low energy cost of FES in the sitting position and during usage of FES as an orthotic device for standing, confirming the beneficial effect of FES for spastic paraplegics. However, effort invested during ambulation by means of FES was found exhaustive and FES is therefore advisable for young subjects mainly

Isakov E., Mizrahi J., and Najenson T. (1986) Biomechanical and physiological evaluation of FES-activated paraplegic patients. J. Rehabil. Res. Dev. 23, 9-19.
Abstract: Four paraplegic patients with traumatic upper motor neuron lesions at the spinal levels between D5 and D12 were activated by functional electrical stimulation (FES) and evaluated biomechanically and physiologically. After a training program aimed at strengthening the muscles of the lower legs, the patients were able to stand up, maintain the standing position, and walk for short distances while being supported. Biomechanical evaluation included weight bearing on the patients' own legs during standing as measured on a force platform and analysis of the time-distance parameters of the stride during walking as measured on a walkway. Physiological evaluation included heart rate and oxygen consumption at rest, when activated by FES in the sitting position, during standing, and during walking. The results obtained indicate that while significant standing and walking performances are achieved, the corresponding physical effort can reach relatively high levels requiring the support of anaerobic energy sources. The practical implications of these results are discussed

Isakov E., Douglas R., and Berns P. (1992) Ambulation using the reciprocating gait orthosis and functional electrical stimulation. Paraplegia 30, 239-245.
Abstract: Until recently, rehabilitation engineering offered 2 different methods to improve daily living independence for spinal cord paralyzed subjects. One, the use of various orthotics and the other, the application of functional electrical stimulation. In the present work we chose to combine reciprocating gait orthosis (RGO) with functional electrical stimulation (FES) into one hybrid system. A detailed biomechanical and clinical instruction for the use of this system is given. Results obtained from application of the hybrid system on a complete T4 paraplegic patient demonstrate that the most significant contribution was the reduced invested energy cost required for stand-up and for ambulation

Jacobs P.L., Nash M.S., Klose K.J., Guest R.S., Needham-Shropshire B.M., and Green B.A. (1997) Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 2. Effects on physiological responses to peak arm ergometry. Arch. Phys. Med. Rehabil. 78, 794-798.
Abstract: OBJECTIVE: To examine the task-nonspecific effects of functional neuromuscular stimulation (FNS)-assisted ambulation training on the physiological responses of persons with paraplegia to upper extremity exercise challenge. DESIGN: Before-after trial. SETTING: Human spinal cord injury (SCI) applied research laboratory. PARTICIPANTS: Twelve men and three women with m

Jaeger R.J., Yarkony G.M., Roth E.J., and Lovell L. (1990) Estimating the user population of a simple electrical stimulation system for standing. Paraplegia 28, 505-511.
Abstract: Many laboratory demonstrations have been reported on standing or walking with the aid of electrical stimulation. These demonstrations have typically been in small numbers of selected spinal cord injured individuals. The extent to which this technology might ultimately be applicable to the spinal cord injured population at large is not presently known. This study reports estimates of the size of the potential user population of a specific surface electrical stimulation device and protocol. The medical records were reviewed of 192 patients with traumatic thoracic, lumbar, or sacral spinal cord injury resulting in paraplegia. Based on the inclusionary criteria, between 20 and 48 patients (10.4% and 25%) of this sample population could be considered eligible for this surface stimulation protocol. As approximately 45% of the USA population of spinal cord injured individuals have paraplegia, the results suggest that between 4.7% and 11.25% of all spinal cord injured persons in the USA might be potential users of this particular electrical stimulation technology

Jaeger R.J. (1992) Lower extremity applications of functional neuromuscular stimulation. Assist. Technol. 4, 19-30.
Abstract: Functional electrical stimulation (FES) applications in the lower extremity are common in research laboratories, but clinical applications are minimal. This review summarizes current knowledge with respect to clinical application. When electrical stimulation is used in clinical applications for functional movement such as standing and walking, it is typically applied in an open-loop manner; a predetermined stimulus pattern is delivered regardless of the consequences of the actual movement. Few clinical applications of FES involve closed-loop control because of the numerous difficulties involved in its application. As with any volitional muscle contraction, electrically stimulated muscle contractions will exhibit fatigue. Although the dynamics of fatigue may differ, electrically stimulated muscle contractions cannot be continuously sustained, and if the duty cycle is too severe, even alternating periods of rest and contraction cannot be sustained at a constant force level. The exact nature of fatigue is highly specific to the past history of the individual muscle and to the individual subject. Despite their intricate detail, quantitative modeling studies have not yet been applied extensively to clinical applications. Present implantable systems are not yet a viable option for clinical application. It is not clear whether more success with surface or percutaneous systems must first be achieved to justify implantation or whether greater improvements in implantable technology and surgical protocols are needed before implantable systems will become practical. It is clear that almost any reasonably designed stimulation protocol will increase muscle bulk. The existence of other therapeutic benefits and their cost/benefit ratios remain to be fully established. It is possible to stand through bilateral stimulation of the quadriceps. Using surface electrodes, this technique is achievable in any physical therapy clinic having minimal expertise in neuromuscular stimulation. FES-aided standing must be conducted as a research project with a protocol approved by the local institutional review board, as there are currently no FDA-approved stimulation devices for standing. Multichannel FES systems are not currently available for clinical application in the United States. This may change if the "Parastep" system receives FDA approval. Percutaneous and implanted systems are years away from commercialization and clinical availability. Hybrid systems, based primarily on the reciprocating gait orthosis (RGO), are presently the only clinically available form of walking that includes some form of FES assistance. The costs and benefits of adding FES to the RGO and the long-term user acceptance rate for these systems remain to be determined

Jonic S., Jankovic T., Gajic V., and Popovic D. (1999) Three machine learning techniques for automatic determination of rules to control locomotion. IEEE Trans. Biomed. Eng 46, 300-310.
Abstract: Automatic prediction of gait events (e.g., heel contact, flat foot, initiation of the swing, etc.) and corresponding profiles of the activations of muscles is important for real-time control of locomotion. This paper presents three supervised machine learning (ML) techniques for prediction of the activation patterns of muscles and sensory data, based on the history of sensory data, for walking assisted by a functional electrical stimulation (FES). Those ML's are: 1) a multilayer perceptron with Levenberg-Marquardt modification of backpropagation learning algorithm; 2) an adaptive-network-based fuzzy inference system (ANFIS); and 3) a combination of an entropy minimization type of inductive learning (IL) technique and a radial basis function (RBF) type of artificial neural network with orthogonal least squares learning algorithm. Here we show the prediction of the activation of the knee flexor muscles and the knee joint angle for seven consecutive strides based on the history of the knee joint angle and the ground reaction forces. The data used for training and testing of ML's was obtained from a simulation of walking assisted with an FES system [39]. The ability of generating rules for an FES controller was selected as the most important criterion when comparing the ML's. Other criteria such as generalization of results, computational complexity, and learning rate were also considered. The minimal number of rules and the most explicit and comprehensible rules were obtained by ANFIS. The best generalization was obtained by the IL and RBF network

Kagaya H., Shimada Y., Sato K., Sato M., Iizuka K., and Obinata G. (1996) An electrical knee lock system for functional electrical stimulation. Arch. Phys. Med. Rehabil. 77, 870-873.
Abstract: An electrical knee lock system that can be combined with functional electrical stimulation was designed for paraplegic patients. This knee system unlocks the knee electrically and allows knee flexion during the swing phase of the gait. When the knee is extended by electrical stimulation of the knee extensors, the knee is automatically locked by the weight of the locking bar, and the stimulation of the knee extensors is stopped. Since the knee extensors are stimulated for only a short period, muscle fatigue of the knee extensors seldom occurs. We applied this system to a T8 completely paraplegic patient. Standing-up, standing, walking, and sitting-down motions were all restored by our hybrid system. No electrical stimulation was necessary during standing, and the knee extensors were stimulated during only a small percentage of the 1-gait cycle

Karcnik T. and Kralj A. (1997) Stability and energy criteria in healthy and paraplegic subject gait. Artif. Organs 21, 191-194.
Abstract: The functional electrical stimulation (FES) assisted gait of paraplegic patients is inferior to that of healthy subjects. The difference can be observed in terms of speed, upright balance, biomechanical energy consumption, and generation of propulsion forces in the direction of walking. The biomechanical structure of paraplegic subjects is the same as that of normal ones; however, the mode of walking differs significantly because of the reduced number of activated muscles and primitive control. The healthy subject is utilizing a 2-point dynamically stable gait. The paraplegic patient is using 4-channel FES and utilizing a 4-point statically stable gait. We believe that the FES gait can be improved if converted into a semidynamically or dynamically stable gait. The gait is considered statically stable if the center of gravity (COG) projection on the ground (PCOG) is inside the supporting area. For a quadruped, this is only possible if it is utilizing a creeping crawl gait. In this paper, the relationship between PCOG and the supporting area are discussed as a criterion for dynamic stability assessment. Results are shown for 3 different modes of 2-point and 4- point gaits

Karmel-Ross K., Cooperman D.R., and Van Doren C.L. (1992) The effect of electrical stimulation on quadriceps femoris muscle torque in children with spina bifida. Phys. Ther. 72, 723-730.
Abstract: The effects of neuromuscular electrical stimulation (NMES) on the torque production of the quadriceps femoris muscles were examined in five children with spina bifida. Two male subjects, aged 5 and 12 years, and three female subjects, aged 5, 12, and 21 years, participated in the study. Surface stimulation was applied to the quadriceps femoris muscles of one lower extremity for 30 minutes each day over an 8-week period. At 0, 4, and 8 weeks, maximum isometric voluntary knee extension torques were measured for both control and stimulated lower extremities with a dynamometer at 0, 15, 30, 45, and 60 degrees of knee flexion. The three oldest subjects had torque measurements of acceptable reliability (intraclass correlation coefficient greater than .72). Two of these three subjects also had significant increases in the torque produced by the stimulated limb relative to the torque produced by the control limb. The data were unreliable from the two youngest subjects. Completion times for functional tasks (walking and step ascension/descension) were also recorded before and after the 8 weeks of stimulation. The completion times were lower following stimulation for four subjects

Karpovich A.L. and Smolianinov V.V. (1977) [Induced locomotion in the myriapod Julus sp.]. Zh. Evol. Biokhim. Fiziol. 13, 31-38.
Abstract: Coordinated locomotor activity in the decapitated millipede Julus sp. was induced either by mechanical stimulation of the legs with the aid of a treadmile band, or by electrical stimulation of separate parts of the abdominal nervous cord. For the walking induced by mechanical stimulation of the legs, it was shown that: 1) after the "support phase", an additional phase of locomoter cycle, i. e. a "pause phase", is registered; 2) the relationships between kinematic parameters are similar to those recorded during normal walking of the intact millipede and correspond to walking at the lowest velocity. In the case of locomotion induced by electrical stimulation, a "start locomotion threshold" was observed: if stimulation level exceeds this threshold, forward walking is induced being the faster the stronger this stimulation. Besides, the second threshold phenomenon was fo

Kawasaki H., Watanabe S., Oishi R., and Ueki S. (1980) Effects of delta-9-tetrahydrocannabinol on the cardiovascular system, and pressor and behavioral responses to brain stimulation in rats. Jpn. J. Pharmacol. 30, 493-502.
Abstract: Effects of delta-9-tetrahydrocannabinol (delta 9-THC) on the cardiovascular system, and pressor and behavioral responses to brain stimulation were investigated in rats. In urethane-anesthetized rats, intravenous administration of delta 9-THC (1, 2 and 5 mg/kg) produced a significant and transient dose-related rise but no fall in blood pressure. delta 9-THC at these doses also produced marked reduction in heart rate which was antagonized by atropine (0.5 mg/kg i.v.) or bilateral vagotomy. In freely moving rats with chronically implanted electrodes and arterial cannula implants, intraperitoneal administration of delta 9-THC (4, 6 and 8 mg/kg) induced a rise in blood pressure and marked bradycardia. Abnormal behavior such as catalepsy, walking backwards and pivoting was also observed. delta 9- THC failed to inhibit the pressor responses to electrical stimulation of the posterior hypothalamus and midbrain reticular formation, whereas the drug suppressed the behavioral responses to stimulation of both regions. It is concluded that the cardiovascular effects seen with delta 9-THC injection are mainly the result of alteration of the efferent vagal activity by acting on the central nervous system and a more potent influence is exerted on the behavioral changes than on autonomic responses to brain stimulation

Kawasaki H., Watanabe S., and Ueki S. (1980) Effects of chronic administration of delta 9-tetrahydrocannabinol on the cardiovascular system, and pressor and behavioral responses to brain stimulation in freely moving rats. Eur. J. Pharmacol. 65, 63-69.
Abstract: The effects of chronic administration of delta 9-THC on the cardiovascular system, and the pressor and behavioral responses to brain stimulation were investigated in freely moving rats with chronic electrode and arterial cannula implants. delta 9-THC at a dose of 6 mg/kg was injected intraperitoneally once a day for 10 days through an abdominal cannula. On the first day, delta 9-THC induced a significant decrease in heart rate and rise in blood pressure. The animals exhibited abnormal behavior such as catalepsy, walking backward and pivoting. On the 5th day, the bradycardia induced by delta 9-THC markedly decreased and on the 10th day tachycardia was observed. The pressor effect of delta 9-THC significantly increased on the 5th and 10th days. However, delta 9-THC-induced abnormal behavior was observed without any changes following chronic administration. delta 9-THC inhibited the pressor response and behavioral changes to electrical stimulation of the posterior hypothalamus and midbrain reticular formation. No tolerance developed to these depressive effects of delta 9-THC after chronic treatment. These data suggest that tolerance develops only to bradycardic effect of delta 9-THC and that the decrease in vagal activity may play some role in the development of tolerance

Keenan M.A.E., Perry J., Jordan C. (1984) Factors affecting balance and ambulation following stroke. Clin Orthop Rel Res 182:165-171.

Kerrigan D.C., Gronley J.K., Perry J. (1991) Stiff-legged gait in spastic paralysis: a study of quadriceps and hamstring activity. Am J Phys Med 70:294-300.

Kern H. (1997) Functional electrical stimulation in paraplegic spastic patients. Artif. Organs 21, 195-196.
Abstract: We are reporting on the clinical and physiological effects of 8 months of functional electrical stimulation (FES) of the quadriceps femoris muscle on 10 paraplegic patients. Each patient had muscle biopsies, computed tomography (CT) muscle diameter measurements, and knee extension strength testing both before and after 8 months of FES training. Skin perfusion was documented through infrared telethermography and xenon clearance; muscle perfusion was recorded through thallium scintigraphy. After 8 months of FES training, the baseline skin perfusion showed an 86% increase; muscle perfusion was augmented by 87%. Muscle fiber diameters showed an average increase of 59% after 8 months of FES training. Muscles in patients with spastic paresis showed an increase in aerobic and anaerobic muscle enzymes up to the normal range of healthy humans. The increment in muscle area, as visible on CT scans of the quadriceps femoris muscle, was 30%. Using FES, we were able to improve metabolism and to induce positive trophic changes in our patients' lower extremities. In spastic paraplegics, rising and walking achieved through FES are much better training than FES ergometer training. Larger muscle masses are activated, and the heart rate is increased; therefore, the impact on cardiovascular fitness and metabolism is much greater. This effectively addresses and prevents the problems that result from inactivity in paraplegic patients

Kobetic R., Triolo R.J., and Marsolais E.B. (1997) Muscle selection and walking performance of multichannel FES systems for ambulation in paraplegia. IEEE Trans. Rehabil. Eng 5, 23-29.
Abstract: A minimal set of muscles (8 to 16) were identified as candidates for implantation in a clinical system to provide walking function to individuals with complete paraplegia using functional electrical stimulation (FES). Three subjects with complete motor and sensory paraplegia had percutaneous intramuscular electrodes implanted in all major muscles controlling the trunk, hips, knees, and ankles. Stimulation patterns for walking with FES were generated for different sets of eight and 16 muscles. The quality and repeatability of the resulting gait produced by walking patterns consisting of various combinations of muscles were determined. Most eight-channel stimulation patterns resulted in scissoring or insufficient hip flexion, preventing forward progression. One eight-channel system allowed a maximum speed of 0.1 m/s with a cadence of 22 steps/min and a stride length less than 0.3 m. Improved walking performance was observed with 16 channels of stimulation. This ranged from slow

Kobetic R., Triolo R.J., Uhlir J.P., Bieri C., Wibowo M., Polando G., Marsolais E.B., Davis J.A., Jr., and Ferguson K.A. (1999) Implanted functional electrical stimulation system for mobility in paraplegia: a follow-up case report. IEEE Trans. Rehabil. Eng 7, 390-398.
Abstract: A 16-channel functional electrical stimulation (FES) system has been implanted in a person with T10 paraplegia for over a year. The system consists of two eight-channel radio frequency controlled receiver- stimulators delivering stimuli through a network of 14 epimysial and two intramuscular electrodes. Using this system and a walker for support, the subject was able to stand up for 8 min and walk regularly for 20 m. The standing duration was limited by arm fatigue since upper extremities supported an average of 25% of body weight. This was due to suboptimal hip extension and some undesired recruitment of rectus femoris and sartorius with stimulation of quadriceps electrodes. The left quadriceps exhibited rapid fatigue that limited walking distance and duration. The metabolic energy requirements were well within the aerobic limits of the sedentary paraplegic population. At one-year follow-up evaluation all electrodes are functional except one intramuscular electrode. The implant caused no adverse physiological effects and the individual reported health benefits such as increased energy and overall fitness as a result of the FES system use. With further improvements in muscle response through innovative surgical techniques, the 16-channel implanted FES system can be a viable addition to exercise and mobility function in persons with paraplegia

Komiyama T., Zehr E.P., and Stein R.B. (2000) Absence of nerve specificity in human cutaneous reflexes during standing. Exp. Brain Res. 133, 267-272.
Abstract: Cutaneous reflexes in lower limb muscles were recorded from healthy human subjects after non-noxious electrical stimulation of superficial peroneal (SP), sural and distal tibial nerves while subjects: (1) made graded voluntary contractions of the ankle and knee extensor and flexor muscles while mimicking late stance or heel strike limb positions; and (2) walked on a treadmill at speeds of 2 and 4 km/h. During standing, net reflexes were predominantly suppressive and graded with background EMG. In contrast, during walking net reflexes were mostly facilitatory and uncorrelated with background EMG. Opposite signs (negative during standing, positive during walking) and significant differences of the reflex ratio (net reflex/background EMG) were seen in most leg muscles. The nerve stimulated did not determine the sign of the net reflex while standing: nerve specificity was absent. We suggest that during standing, where maintenance of posture is of primary importance, there is a reduction of effort that led to increased cutaneous input (i.e., a global suppressive response), while during walking there is a modulation of reflexes which is independent of muscle activation level but closely tied to events occurring in the step cycle

Kostov A., Hansen M., Haugland M., and Sinkjaer T. (1999) Adaptive restriction rules provide functional and safe stimulation pattern for foot drop correction. Artif. Organs 23, 443-446.
Abstract: We report on our advances in sensory feedback data processing and control system design for functional electrical stimulation (FES) assisted correction of foot drop. We have applied 2 methods of signal purification on the bin integrated electroneurogram (i.e., optimized low pass filtering and wavelet denoising) before training adaptive logic networks (ALN). ALN generated stimulation control pulses, which correspond to the swing phase of the impaired leg when dorsal flexion of the foot is necessary to provide safe ground clearance. However, the obtained control signal contained sporadic stimulation spikes in the stance phase, which can collapse the subject, and infrequent broken stimulation pulses in the swing phase, which can result in unpredictable consequences. In this study, we have introduced adaptive restriction rules (ARR), which are initially used as previously reported and then dynamically adapted during the use of the system. Our results suggest that ARR provide a safer and more reliable stimulation pattern than fixed restriction rules

Kralj A., Bajd T., and Turk R. (1980) Electrical stimulation providing functional use of paraplegic patient muscles. Med. Prog. Technol. 7, 3-9.
Abstract: The paper presents a short description of the field of electrical stimulation of skeletal muscles and a survey of the recent achievements in the functional electrical stimulation (FES) of paraplegic patients. The major emphasis is placed on the discussion of the basic problems concerning muscle fatigue, muscle retraining and patient selection. Muscle strengthening and exercising procedures using electrical stimulation are described. The obtained properties of retrained muscles with special regard to their fatiguing are clearly documented. The potential possibilities of using FES for performing functional tasks are discussed and the results of preliminary experiments are illustrated. The standing and primitive walking of patient, induced by electrically stimulated paralyzed muscles are presented. Finally, a proposal for an orthotic device using electrical stimulation is described, which enables a paraplegic patient to stand by means of support of his proper bones and muscle forces

Kralj A., Bajd T., Turk R., Krajnik J., and Benko H. (1983) Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES. J. Rehabil. R. D. 20, 3-20.
Abstract: Recent advances in science have aided research toward the restoration of biped gait in paraplegic patients by means of functional electrical stimulation (FES). In this paper it is shown how FES-restrengthened muscles of paraplegic patients have been used for simple FES-assisted standing. Those experiments subsequently led to biped gait-initializing experiments and to simple forms of biped gait synthesis. The purpose of this paper is to show the feasibility of using FES for standing and for restoring biped gait in many paraplegic patients--to present the past achievements, focus on problems, and highlight directions for future research. The results of gait obtained in three complete spinal cord injured patients (out of a series of 17) are shown, using four to six channels of FES. It is also shown how preserved reflex mechanisms of the transected spinal cord can be incorporated and employed for obtaining improved function while at the same time simplifying the FES hardware. Of the three patients reported on in detail here, two patients have managed to walk in parallel bars while the third patient has mastered independent unassisted walking over shorter distances with the aid of a roller walker. The biomechanical and control problems of this last patient's gait are presented in detail

Kralj A., Bajd T., and Turk R. (1988) Enhancement of gait restoration in spinal injured patients by functional electrical stimulation. Clin. Orthop. 34-43.
Abstract: Functional electrical stimulation (FES) was applied in 50 spinal cord injury patients in an effort to restore standing and walking. All patients in the program with lesions from T4-T12 were able to stand by means of FES. Walking, utilizing a four-channel stimulator, was accomplished by 25 patients with lesions in the range from T4-T12. These 25 patients represent approximately 5% of all spinal cord injured patients treated in the authors' rehabilitation facility during this time period. After using the stimulation in a home environment for more than three months, the number of patients who continued to use the stimulation for walking declined, and 16 patients remained ambulatory. The discontinuance of FES was mainly because of the time required to put on and operate the FES system and difficulties adapting to a new home environment and living situation

Kupers R.C., Nuytten D., Castro-Costa M., and Gybels J.M. (1992) A time course analysis of the changes in spontaneous and evoked behaviour in a rat model of neuropathic pain. Pain 50, 101-111.
Abstract: We have previously demonstrated that scratching was significantly increased in a rat model of polyarthritis and that this could be reversed by morphine and electrical stimulation of pain-modulating brain areas. We therefore proposed that scratching might represent a parameter of chronic pain. In this study, we examined the spontaneous behaviour of rats in a model of peripheral neuropathy induced by loosely tying 4 ligatures around the right common sciatic nerve. In half of the animals (N = 7), the ligatures were made with resorbable sutures and, in the other half (N = 7), with non-resorbable sutures of the same size. Postoperatively, scratching was significantly increased at the ligated side. This increase was already observed on the first postoperative day, and maximal effects were reached on the 3rd day. We also observed a qualitative change in the scratching behaviour; postoperatively, scratching was often a vibratory-like shaking of the hind paw in the air. The time course of the increased scratching was time-locked with the development of allodynia to thermal stimulation. No differences were found either in the time course of the increased scratching behaviour or in the time course of the thermal allodynia between the rats ligated with resorbable and with non-resorbable sutures. However, a difference in the walking pattern, as measured by the sciatic functional index (SFI), was observed between the two groups: whereas the SFI normalized after 4 weeks in rats ligated with resorbable sutures, it remained disturbed until the end of the 16-week observation period in the rats ligated with non-resorbable sutures. Morphine 1, 2 and 5 mg/kg dose-dependently reduced the increased scratching behaviour. This was not due to a general depressant effect on the rats' behaviour. This finding is discussed in light of the debate on opioid sensitivity of neuropathic pain. The present results add new evidence that scratching is a possible sign of chronic pain in the animal

Ladouceur M. and Barbeau H. (2000) Functional electrical stimulation-assisted walking for persons with incomplete spinal injuries: changes in the kinematics and physiological cost of overground walking. Scand. J. Rehabil. Med. 32, 72-79.
Abstract: This study was conducted to investigate the change in the kinematics and physiological cost of walking that occurs during training with functional electrical stimulation (FES)-assisted walking in persons with incomplete injuries. The main effect of FES-assisted walking was to change hip excursion and ankle dorsiflexion during swing and at foot contact, whereas training with FES-assisted walking changed the spatio- temporal parameters of walking (walking speed, cycle length and frequency as well as time in stance). The use of FES-assisted walking does not change the walking speed achieved during a 5-minute trial nor the physiological cost of walking but when combined with walking training, eight of the nine participants improved either their physiological cost index or their walking speed. It is concluded that FES-assisted walking changes the joint angular kinematic pattern of walking, but training is necessary to integrate these changes into functional gains

Ladouceur M. and Barbeau H. (2000) Functional electrical stimulation-assisted walking for persons with incomplete spinal injuries: longitudinal changes in maximal overground walking speed. Scand. J. Rehabil. Med. 32, 28-36.
Abstract: This study investigated the changes in maximal overground walking speed (MOWS) that occurred during walking training with a functional electrical stimulation (FES) orthosis by chronic spinal cord injured persons with incomplete motor function loss. The average walking speed over a distance of 10 m was calculated while the participants (n = 14) used their FES orthosis with and without power as well as with the various ambulatory assistive devices available. Within the first year of use, walking with an FES orthosis facilitated use of more advanced ambulatory assistive devices (10/14), improvements in functional mobility (12/14) and increases in the combined (0.26 m/s) and therapeutic (0.25 m/s) MOWS that were correlated (combined: r = 0.57; therapeutic: r = 0.69) with their respective initial MOWS. A longitudinal analysis showed that increases in MOWS followed a pattern of changes best described by either an exponential association (8/12) or a linear (4/12) model. These changes were similar for the combined and therapeutic MOWS (7/11) as well as for the different ambulatory assistive devices (8/9). It is concluded that the increased MOWS during walking training using the FES orthosis is mostly due to a therapeutic effect, implying that mechanisms of plasticity occur during such a training paradigm

Lanmuller H., Bijak M., Mayr W., Rafolt D., Sauermann S., and Thoma H. (1997) Useful applications and limits of battery powered implants in functional electrical stimulations. Artif. Organs 21, 210-212.
Abstract: Battery powered stimulation implants have been well-known for a long time as heart pacemakers. In the last few years, fully implantable stimulators have been used in the field of functional electrical stimulation (FES) for applications like dynamic cardiomyoplasty and electro-stimulated graciloplasty for fecal incontinence. The error rate of battery powered implants is significantly smaller than that for conventional stimulator systems, and the quality of life for the patients is increased because the need for an external power and control unit is eliminated. The use of battery powered implants is limited by the complexity of the stimulation control strategies and the battery capacity. Therefore, applications like the stimulation of lower extremities for walking, cochlea stimulation, or direct muscle stimulation cannot be supported. The improvement of implantable batteries, microcontrollers, and ultralow power products is ongoing. In the future, battery powered implants will also meet the requirements of complex applications. Systems for restoration of hand and breathing functions after spinal cord injury can be the next field of use for battery powered implants. For these purposes, we developed a battery powered multichannel implant with a sufficient life span for phrenic pacing. The problems during development and the limits of this system are described in this paper

Lee S.C., Becker C.N., and Binder-Macleod S.A. (2000) Activation of human quadriceps femoris muscle during dynamic contractions: effects of load on fatigue. J. Appl. Physiol 89, 926-936.
Abstract: Muscle fatigue is both multifactorial and task dependent. Electrical stimulation may assist individuals with paralysis to perform functional activities [functional electrical stimulation (FES), e.g., standing or walking], but muscle fatigue is a limiting factor. One method of optimizing force is to use stimulation patterns that exploit the catchlike property of skeletal muscle [catchlike-inducing trains (CITs)]. Although nonisometric (dynamic) contractions are important parts of both normal physiological activation of skeletal muscles and FES, no previous studies have attempted to identify the effect that the load being lifted by a muscle has on the fatigue produced. This study examined the effects of load on fatigue during dynamic contractions and the augmentation produced by CITs as a function of load. Knee extension in healthy subjects was electrically elicited against three different loads. The highest load produced the least excursion, work, and average power, but it produced the greatest fatigue. CIT augmentation was greatest at the highest load and increased with fatigue. Because CITs were effective during shortening contractions for a variety of loads, they may be of benefit during FES applications

Leung L.S. (1980) Behavior-dependent evoked potentials in the hippocampal CA1 region of the rat. I. Correlation with behavior and EEG. Brain Res. 198, 95-117.
Abstract: As an alternative approach to the study of hippocampal function in relation to behavior, the averaged evoked potentials (AEPs) evoked by electrical stimulation of the Schaffer collaterals (SCH), the alveus and the contralateral hippocampus were recorded at various depths in the hippocampal CA1 region of freely moving rats with chronically implanted electrodes. Significant correlations between AEPs, behavior and EEG were found. At one end of the continuum of AEPs were those recorded during large irregular activity (LIA), an EEG pattern associated with slow-wave sleep or awake-immobility. These AEPs had large early peak and low-amplitude late peaks. At the order end of the continuum, during high frequency theta EEG associated with behaviors such as walking, postural change or phasic paradoxical sleep. AEPs had a smaller early peak, increased later peak(s) and appeared oscillatory. The evoked population spike, a synchronous postsynaptic firing of CA1 neurons, was smaller during behaviors associated with theta than during those associated with LIA. It is postulated that a recurrent inhibitory circuit within the hippocampus can account for the change of the AEPs with EEG and behavior and with stimulus intensity. During theta EEG, the negative feedback may increase such that the evoked population excitatory postsynaptic potential and the evoked population spike decrease and ascillatory response is more readily elecited. The excitability state of hippocampal CA1 may be described by the negative feedback gain in this model

Libersat F., Clarac F., and Zill S. (1987) Force-sensitive mechanoreceptors of the dactyl of the crab: single-unit responses during walking and evaluation of function. J. Neurophysiol. 57, 1618-1637.
Abstract: The activities of individual force-sensitive mechanoreceptors of the dactyl (terminal leg segment) of the crab, Carcinus maenas, have been recorded during free walking. These receptors have also been mechanically and electrically stimulated in freely moving animals to directly evaluate their function in locomotion. All force-sensitive mechanoreceptors fired during the stance phase of walking and were silent during swing. Receptor discharges showed regular phase relationships to bursts in motor neurons of leg muscles. Crabs walk laterally and use the legs of one side either in trailing to actively push the animal to the opposite side, or in leading, to less forcefully pull the animal in that direction. Individual force-sensitive mechanoreceptors differed in their patterns of activity during trailing or leading according to their location on the dactyl. Units of proximal receptors fired more vigorously when used in trailing than in leading. Discharges in trailing were also increased by loading of the animal. In contrast, distal receptors near the dactyl tip fired equally intensely during walking in either direction. Proximal receptors thus encode forces and loads applied to the leg. Distal receptors do not encode loads but can signal leg contact and, potentially, exteroceptive vibrations. Sensory stimulation of force-sensitive mechanoreceptors was produced during walking by a device that imposed continuous mechanical bending of the dactyl and by electrical stimulation of dactyl nerves. I

Liberson W.T., Holmquest H.J., Scot D., Dow M. (1961) Functional electrotherapy: Stimulation of the peroneal nerve synchronized with the swing phase of gait in hemiplegic patients. Arch Phys Med Rehabil 42, 101-105.

Loeb G.E., Hoffer J.A., and Marks W.B. (1985) Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli. J. Neurophysiol. 54, 578-591.
Abstract: Chronically implanted electrodes were used to record the activity of identified single muscle spindle afferents in awake cats during responses to various types of manual and electrical stimulation. During vigorous cyclical responses such as shaking and scratching, spindle afferents generally maintained at least some activity during both lengthening and shortening of the parent muscle, indicating that the programs for these movements include both e

Maillefert J.F., Eicher J.C., Walker P., Dulieu V., Rouhier-Marcer I., Branly F., Cohen M., Brunotte F., Wolf J.E., Casillas J.M., and Didier J.P. (1998) Effects of low-frequency electrical stimulation of quadriceps and calf muscles in patients with chronic heart failure. J. Cardiopulm. Rehabil. 18, 277-282.
Abstract: PURPOSE: The aim of this preliminary study was to evaluate the effects of low-frequency electrical stimulation of quadriceps and calf muscles on global exercise capacities, skeletal muscle metabolism, calf muscle volume, and cardiac output in patients with chronic heart failure. METHODS: Fourteen patients with chronic heart failure (mean age of 56.4 years +/- 9.1 SD; mean radionuclide left ventricular ejection fraction of 22.3% +/- 8.8 SD) underwent 5 weeks (1 hour per day, 5 days per week) of low-frequency electrical stimulation of quadriceps and calf muscles. RESULTS: Low-frequency electrical stimulation was well tolerated. Exercise capacity and the calf muscles volumes increased significantly after rehabilitation in comparison with prior rehabilitation (the peak oxygen consumption increased from 17.2 mL/(kgmin) +/- 5.3 SD to 19.6 mL/(kgmin) +/- 5.9 SD; the anaerobic threshold increased from 12.3 mL/(kgmin) +/- 3.2 SD to 15.2 mL/(kgmin) +/- 3.3 SD; the 6-minute walking test increased from 419 m +/- 122 SD to 459 m +/- 114.3 SD; the gastrocnemius volume increased from 259.4 cm3 +/- 58 SD to 273.4 cm3 +/- 74 SD, and the soleus volume increased from 319 cm3 +/- 42.9 SD to 338 cm3 +/- 52.5 SD). The New York Heart Association class was improved after rehabilitation. The P-31 nuclear magnetic resonance spectroscopy of gastrocnemius muscle data were not significantly modified after rehabilitation, thereby inferring that no significant improvement of the muscle metabolism occurred. These data reinforce the hypothesis of an increased muscle mass during stimulation. It is noteworthy that the electrical stimulation did not increase cardiac output at any stage; an enormous asset in favor of this mode of rehabilitation. CONCLUSION: These results suggest that low- frequency muscular electrical stimulation is well tolerated, induces an increased exercise capacity in patients with chronic heart failure, without an undesirable increase in cardiac output

Malezic M., Bogataj U., Gros N., Kelih B., Kljajic M., and Acimovic-Janezic R. (1987) Evaluation of gait with multichannel electrical stimulation. Orthopedics 10, 769-772.
Abstract: Short, intensive multichannel electrical stimulation therapy was evaluated in 14 hemiplegics after stroke or head injury. The stimulation of the peroneal nerve, soleus, quadriceps, hamstring, gluteus maximus, and triceps brachii muscles with individually preprogrammed sequences was applied by surface electrodes at the beginning of gait rehabilitation. The patients started walking with the support of a therapist, gradually increased the walking distance and all reached independent ambulation with a crutch after an average of 14 stimulation sessions. A portable microprocessor six-channel stimulator/stride analyzer enabled the collection of gait parameters and recording of statistical mean values of stride time, gait symmetry, right and left stance times, and their standard deviations. Without additional equipment, several hundred stimulated strides were measured during each stimulation session

Malezic M., Bogataj U., Gros N., Decman I., Vrtacnik P., Kljajic M., and Acimovic-Janezic R. (1992) Application of a programmable dual-channel adaptive electrical stimulation system for the control and analysis of gait. J. Rehabil. Res. Dev. 29, 41-53.
Abstract: A dual-channel electrical stimulation system with a stimulator and a programmer/stride analyzer was designed for clinical rehabilitation of gait and for subsequent daily use as an orthotic aid. The stimulator, with controls to adjust amplitude only (50 mA), adapts chosen stimulation sequences to the walking rate of a patient. Pulse duration (50-500 microseconds), frequency (5-120 Hz), shape (symmetrical biphasic, monophasic), stimulation sequences (16 stride segments) and their cycle (2-12 sec), and right/left foot-switch choices are selected for each patient and programmed into a separate unit. The programming unit also statistically processes the foot-switch data collected by the stimulator. The device was evaluated with regard to the programmable parameters, effectiveness during gait, and feasibility in clinical use. It was applied to 11 stroke patients and 10 brain injury patients during gait, stimulating 22 combinations of peroneal nerve and hamstring, quadriceps, triceps brachii, and gluteus maximus muscles. Forces on both feet, equinovarus, knee extension and hyperextension, elbow flexion, and hip extension were corrected. Selection of the stimulation sequences, their adaptation, range of pulse duration, and valid statistics were verified. Improved forces and joint angles were recorded together with significant changes in the stride time, length, and velocity by the stimulation

Malezic M. and Hesse S. (1995) Restoration of gait by functional electrical stimulation in paraplegic patients: a modified programme of treatment. Paraplegia 33, 126-131.
Abstract: Restoration of standing and of gait by functional electrical stimulation in clinically complete paraplegic patients was modified in the course of treatment and in the stimulation parameters. By substituting an initial cyclic muscle strengthening with an active stimulated standing, four patients with T3-11 lesions started walking with electrical stimulation in 10-17 days. They walked without ankle- foot orthoses. With a satisfactory stride length of 0.75-0.97 m, their gait velocity ranged from very slow to that of a leisurely healthy gait. Already established stimulation of the quadriceps muscles for standing and of the peroneal nerves for lower limb flexion during the swing phase of gait was applied. Diminished limb flexion after several weeks was restored by an increase of the stimulation frequency of the peroneal nerve from 20 to 60 Hz. EMG and kinesiological measurements displayed an improved direct response of the ankle as well as of the reflex mediated hip, knee and ankle flexion response. At the same time stimulation frequency was reduced to 16 Hz for the quadriceps muscles in order to reduce fatigue

Marple-Horvat D.E. and Armstrong D.M. (1999) Central regulation of motor cortex neuronal responses to forelimb nerve inputs during precision walking in the cat. J. Physiol 519 Pt 1, 279-299.
Abstract: 1. The responses of neurones in forelimb motor cortex to impulse volleys evoked by single pulse electrical stimulation (at 1.5 or 2 times the threshold for most excitable nerve fibres) of the superficial radial (SR) and ulnar (UL) nerves of the contralateral forelimb were studied in awake cats both resting quietly and walking on a horizontal ladder. Nerve volley amplitude was monitored by recording the compound action potential elicited by the stimulus. 2. In the resting animal 34/82 (41%) cells yielded statistically significant responses to SR stimulation, and 20/72 (28%) responded to UL stimulation. Some responses were confined to or began with an increase in firing probability ('excitatory' responses) and others with a decrease in firing ('inhibitory' responses), typically including a brief interruption of the spike train (zero rate). Cells responding to both nerves usually yielded responses similar in type. Most (78%) response onset latencies were less than 30 ms. Responses involved the addition or subtraction of from 3.4 to 0.1 impulses stimulus-1 (most <1 impulse stimulus-1). The distribution of response sizes was continuous down to the smallest values, i.e. there was no 'gap' which would represent a clear separation into 'responsive' and 'unresponsive' categories. Responses were commonest in the lateral part of the pericruciate cortex, and commoner among pyramidal tract neurones (PTNs) than non- PTNs. 3. During ladder walking most cells generated a rhythmic step- related discharge; in assessing the size of responses to nerve stimulation (20 studied, from 13 cells) this activity was first subtracted. Response onset latencies (90% <30 ms) and durations showed little or no change. Although most cells were overall more active than during rest both 'excitatory' and 'inhibitory' responses in both PTNs and non-PTNs were often markedly reduced in large parts of the step cycle; over some (usually brief) parts responses approached or exceeded their size during rest, i.e. response size was step phase dependent. Such variations occurred without parallel change in the nerve compound action potential, nor were they correlated with the level of background firing at the time that the response was evoked. When responses to both nerves were studied in the same neurone they differed in their patterns of phase dependence. 4. The findings are interpreted as evidence for central mechanisms that, during 'skilled', cortically controlled walking, powerfully regulate the excitability of the somatic afferent paths from forelimb mechanoreceptors (including low threshold cutaneous receptors) to motor cortex. Retention (or enhancement) of responsiveness often occurred (especially for ulnar nerve) around footfall, perhaps reflecting a behavioural requirement for sensory input signalling the quality of the contact established with the restricted surface available for support

Marquis J.K. and Mautner H.G. (1975) On the similar effects of chemical reduction and electrical stimulation in walking leg nerve bundles of the spider crab. Mol. Pharmacol. 11, 361-368.

Marsolais E.B. and Kobetic R. (1983) Functional walking in paralyzed patients by means of electrical stimulation. Clin. Orthop. 30-36.
Abstract: Three partially paralyzed patients were unable to walk even after maximal rehabilitation attempts at a major rehabilitation center. One 36-year-old man had transverse myelitis, a 57-year-old man had had a stroke, and the third patient, a 35-year-old man, had incurred a traumatic brain injury. The three patients were unable to flex the hips, had adductor spasm and weak hip and knee extension, and lacked ankle dorsiflexion. Intramuscular stainless steel wire electrodes activated by timers were placed in the quadriceps, hip flexors, extensors, and abductors, as needed. Muscle force and foot contact evaluations were done using the Cybex and the Cleveland Veterans Administration Gait Laboratory. After implantation of intramuscular electrodes, all three patients had improved function but still desired some supervision in walking. A ten-fold increase in knee torque was noted in one patient, thereby providing him with nearly normal strength. No implant complications were noted. The study demonstrated the feasibility of functional neuromuscular stimulation (FNS) gait augmentation in a previously nonwalking patient outside the laboratory. Further improvements will require the development of an implantable, multichannel, programmable microprocessor-controlled stimulator

Marsolais E.B. and Kobetic R. (1987) Functional electrical stimulation for walking in paraplegia. J. Bone Joint Surg. Am. 69, 728-733.
Abstract: In paraplegic subjects who had functional transection of the spinal cord at a level between the fourth and the eleventh thoracic vertebra, independent reciprocal walking was achieved with the use of a portable microprocessor-controlled stimulator that electrically activated the muscles through percutaneous intramuscular wire electrodes. The electrodes were implanted, by means of hypodermic needles, in the flexors, extensors, abductors, and adductors of the hip; the extensors of the knee; and the plantar flexors and dorsiflexors of the ankle. The subjects had strong, selective, and reproducible muscular contractions that increased in strength during the twenty-two to forty-four months (average, thirty-two months) of training with the regimen. A basic pattern of stimulation was adapted for each individual; each step was initiated by the subject using a hand-operated switch. The subjects progressed to the use of a walker for support, and two of them were able to walk using axillary crutches. Three subjects were able to climb stairs

Marsolais E.B., Kobetic R., Polando G., Ferguson K., Tashman S., Gaudio R., Nandurkar S., and Lehneis H.R. (2000) The Case Western Reserve University hybrid gait orthosis. J. Spinal Cord. Med. 23, 100-108.
Abstract: Six individuals with paraplegia and injury levels from C-1 through T-12 participated in a study to evaluate the functional capabilities of a hybrid gait orthotic system. Subjects learned to use a custom-built reciprocal gait orthosis without stimulation and with electrical stimulation activating between 4 and 16 muscles. Outcomes were scored with standard physical therapy measures including the Tinetti test, a timed get up and go, Borg rating of perceived exertion, and the Functional Index Measure (FIM). Subjects have successfully accomplished sit to stand, stand to sit, and walking maneuvers measured for time, speed, and distance. Metabolic consumption was measured for walking in the light work region of 5.1 to 6.5 metabolic equivalents (METs) 1 MET = 3.5 ml of O2/kg/min with hybrid gait orthosis. Perceived exertion as measured with the Borg scale indicated that use of the bracing system with functional electrical stimulation was "easier" than without stimulation. Subjects using a hybrid system were able to walk up to 350 m at average speeds of 0.25 m/s. Walking speeds for 30- and 50-meter distances reached 0.45 m/s. Additionally, walking distances with stimulation were 2 times greater than those of non-stimulated reciprocal gait. FIM scores indicated that system users would become slightly more independent in mobility. Results were used to determine the most useful brace modifications for the next generation of Case Western Reserve University hybrid gait orthoses to allow an expanded function that will include stair climbing and side stepping

Matjacic Z., Munih M., Bajd T., and Kralj A. (1996) Voluntary telemetry control of functional electrical stimulators. J. Med. Eng Technol. 20, 11-15.
Abstract: With the assistance of crutches and functional electrical stimulation (FES) we are able to restore standing and simple gait in some spinal cord injured (SCI) patients. In the present rehabilitative systems the patient divides the gait cycle into 'stance' and 'swing' phase by using pushbuttons mounted in the handles of the crutches. These are then hard wired to the functional electrical stimulator. We present the development and evaluation of a surface mount technology based telemetry system that provides reliable and interference resistant wireless control of FES assisted walking. The system makes use of radio frequency carriers operating at a frequency of 40 MHz. Crutch pushbutton signals are coded and transferred from the transmitter placed in the crutch to the receiver which is firmly attached to the patient's waist and connected to the stimulator. The telemetry system was found to be of special importance for both complete and incomplete SCI subjects and is currently in use at the Rehabilitation Institute of the Republic of Slovenia

Maxwell D.J., Granat M.H., Baardman G., and Hermens H.J. (1999) Demand for and use of functional electrical stimulation systems and conventional orthoses in the spinal lesioned community of the UK. Artif. Organs 23, 410-412.
Abstract: The use of and demand for functional electrical stimulation (FES) systems and conventional orthoses in the spinal cord lesioned population was assessed. The assessment was conducted by a postal survey of the members of the spinal injury associations in the U.K. Out of all the respondents, only 2% had used an FES system for walking. In comparison, 13% had used some kind of orthosis. Of the small numbers who had used an FES system for walking, more than half had no functional walking abilities. The majority of orthosis users had some independent walking ability. The demand for walking improvements was high among the respondents although this was not matched by the demand for improved orthotic solutions. In conclusion, it would appear that there is a need for simple FES systems offering walking improvement to the incomplete spinal cord lesioned (SCI) subject

McNeal D.R., Nakai R.J., Meadows P., and Tu W. (1989) Open-loop control of the freely-swinging paralyzed leg. IEEE Trans. Biomed. Eng 36, 895-905.
Abstract: An experimental model has been used to study issues that are relevant to the use of electrical stimulation to help paralyzed individuals walk. Modulated stimulation sequences for the quadriceps muscles were manually selected using an iterative trial-and-error procedure to cause the knee angle to follow a specific movement pattern (desired trajectory). Four paraplegic subjects were tested before and after an eight-week program in which the quadriceps were exercised daily with electrical stimulation. It was found that 12.6 +/- 2.9 iterations were required to approximate the desired trajectory. The average error of the final match between the actual and desired trajectories was 2.1 degrees +/- 0.7. Repeated responses were extremely consistent; the average difference between successive trials was less than 1 degree in 81 percent of the trials. When the stimulation sequence was repeated every 3 s for 50 cycles, however, there was a progressive degradation in the response, even in exercised legs, that demonstrated the limitations of open-loop control. Stimulus modulation envelopes for all four subjects were similar in shape (although varied in amplitude) indicating that the iterative process can be shortened by starting with an "average" modulation envelope. Stimulation sequences achieved accurate matches of the desired trajectory on subsequent days when adjusted by a simple gain factor. The relevance of these results to multichannel control of walking is discussed

Merati G., Sarchi P., Ferrarin M., Pedotti A., and Veicsteinas A. (2000) Paraplegic adaptation to assisted-walking: energy expenditure during wheelchair versus orthosis use. Spinal Cord. 38, 37-44.
Abstract: STUDY DESIGN: To study the energy cost of locomotion during ambulation with different orthoses (HIP Guidance Orthosis Orlau Parawalker (PW), n=4; Reciprocating Gait Orthosis (RGO), n=6; RGO + FNS, n=4). OBJECTIVES: Since high energy costs of locomotion have been proposed as a major reason for early rejection of orthotic use, our aims were (a) to evaluate the impact of functional neuromuscular stimulation (FNS) on energy expenditure during orthosis-assisted ambulation; (b) to study whether energy expenditure data can predict the poor long-term patients' compliance and (c) to assess selection criteria for the assignment of the different types of orthosis. SETTING: The study was completed at the Center of Sports Medicine and Center of Bioengineering, don C. Gnocchi Foundation, IRCCS, Milan, Italy. METHODS: The HR/VO2 relationship and the energy cost of locomotion (C) were studied in 14 patients (lesion level C7-T11) during wheelchair (WHCH) use at various speeds and during locomotion with different orthotic devices. Patients' s

Mingoli A., Sciacca V., Tamorri M., Fiume D., and Sapienza P. (1993) Clinical results of epidural spinal cord electrical stimulation in patients affected with limb-threatening chronic arterial obstructive disease. Angiology 44, 21-25.
Abstract: Between 1982 and 1990, 76 patients (33 women, 43 men, mean age 71.4 +/- 10 years) affected with limb-threatening peripheral vascular disease (claudication < 20 m: 3 patients; rest pain: 10 patients; necrosis1 smaller than 3 cm2: 28 patients; necrosis2 larger than 3 cm2: 35 patients) not amenable to medical and/or surgical therapy, were treated by epidural spinal cord electrical stimulation (ESES). Effectiveness of ESES was evaluated by consideration of pain control, walking distance, and healing of ischemic lesions. At a mean follow-up of twenty-six months (range: one to seventy-six) 44 limbs (58%) were amputated (rest pain 2; necrosis1 13; necrosis2 29) and 39% of necrotic lesions smaller than 3 cm2 healed. The overall limb salvage rate was 42%. Pain control was obtained in 80% of patients at the one-year and 75% at the two-year follow-up, with infrequent use of pain relievers. Despite the poor clinical results observed, the limb salvage rate testifies to the effectiveness of ESES in limb-threatening ischemia. Moreover, the authors noticed a good ESES effect on pain relief, maximal in the early and intermediate postimplant periods. In conclusion ESES must be considered the last resort in peripheral vascular disease in patients in whom medical and/or surgical therapies are ineffective or impossible. Necrotic lesions larger than 3 cm2 contraindicate, in their opinion, ESES implant

Montgomery J., Perry J. (1987) Stroke patient gait and orthotics indications. In: Brandstater M., Basmajian J. [Eds]: Stroke Rehabilitation. Baltimore, Williams & Wilkins.

Mooney V., Perry J., Nickel V.L. (1969) Surgical and non-surgical orthopaedic care of stroke. In: American Academy of Orthopaedic Surgeons [Eds]: Instructional Course Lectures, Vol XVIII, J2. St. Louis, CV Mosby Co.

Moynahan M., Mullin C., Cohn J., Burns C.A., Halden E.E., Triolo R.J., and Betz R.R. (1996) Home use of a functional electrical stimulation system for standing and mobility in adolescents with spinal cord injury. Arch. Phys. Med. Rehabil. 77, 1005-1013.
Abstract: OBJECTIVE: Functional electrical stimulation (FES) is a technology that may allow some patients with spinal cord injury (SCI) to integrate standing and upright mobility with wheelchair mobility. The purpose of this study was to document the patterns of home and community use of a FES system for standing and mobility. DESIGN: A telephone questionnaire was administered every 1 to 4 weeks for a minimum of 1 year. An interview was given at the end of the study to probe the motivators and barriers to home use. SETTING: Training for use of the FES system was performed in an inpatient pediatric rehabilitation setting. Data collection began after the subjects were discharged to home. PARTICIPANTS: Five adolescents with complete, thoracic-level SCI. INTERVENTION: Subjects participated in a program of FES exercise followed by training in basic mobility skills such as standing transfers, maneuvering, level ambulation, one-handed and reaching activities, and stair ascent/descent. MAIN OUTCOME MEASURE: The frequency with which the FES system was used at home and the activities for which it was utilized were documented. Motivators and barriers to FES home use were examined. RESULTS: Subjects donned the FES system on the average once every 3 to 4 days. Between 51% and 84% of the times donned, the system was used for exercise. The remaining times it was used for standing activities, most commonly reaching, one-handed tasks, and standing for exercise. "Motivators" included being able to do things that would otherwise be difficult, perceiving a healthful benefit or a sense of well-being from standing and exercise, and feeling an obligation to stand as a participant in a research study. "Barriers" to FES use included not finding time to use the system, having difficulty seeing opportunities to stand, and being reluctant to wear the FES system all day

Murphy P.R. and Hammond G.R. (1997) Reversal of fusimotor reflex responses during locomotion in the decerebrate cat. Exp. Physiol 82, 837-858.
Abstract: The effect of brief trains of electrical stimulation, at 2, 3 and 20 x threshold (T), of cutaneous afferents in the medial plantar nerve on the discharges of single medial gastrocnemius static and dynamic gamma- efferents has been investigated at rest and during locomotion in a decerebrate cat preparation. The units were classified as dynamic (10 units) or static (10 units) indirectly on the basis of their resting and locomotor discharge characteristics. Responses were assessed by calculating the change in mean gamma-rate during the 100 ms after stimulus onset compared with a control period. At rest, most dynamic neurones were inhibited by stimulation at 2T (9 of 10 units) and above. In contrast, the resting responses of most static neurones were excitatory at 2T (9 of 10 units) and 3T, while 20T produced static gamma-effects that varied in sign. During locomotion the responses of both types of gamma-efferent were phase related. Two patterns were observed with dynamic units. For seven dynamic neurones, at stimulus levels of 2T (7 units) and above, responses during electromyogram (EMG) bursts were inhibitory while those between bursts were not significantly different from zero. However, for three other dynamic units, a phase-related reversal of reflex responses was observed at some stimulus intensities (always 2T, 3 units) comprising inhibition during, and excitation between, EMG bursts. For static neurones, inhibitory (never excitatory) responses occurred during walking at stimulus intensities of 2T (10 units) and above. The locomotor responses of static units were maximum during (3 units) or between (7 units) EMG bursts and were minimum in the opposite phase of EMG activity. A task-related reversal of reflex responses was thus generally apparent (9 of 10 units) to low intensity stimulation (2T) for static gamma-efferents during locomotion (inhibition) compared with rest (excitation). During locomotion there was a significant linear relation between the magnitude of response and the background gamma- rate for static units and those dynamic units that did not exhibit phase-related reflex reversal (total, 17 units). For dynamic gamma- efferents, inhibition at rest and during locomotion occurred at short (spinal) latencies which were not significantly different and are consistent with the involvement of the same interneuronal pathway. We conclude that pathways of opposite sign may dominate the responses of fusimotor neurones to low threshold cutaneous afferents from the plantar surface of the foot depending on behavioural context. Furthermore, the cutaneous reflex responses of both types of gamma- motoneurones during locomotion appear to vary with the source of the afferent input and do not constitute a general excitatory drive. The results are discussed in relation to the role and reflex control of the fusimotor system

Murphy P.R. (1999) Adaptive fusimotor reflex control in the decerebrate cat. Brain Res. 821, 38-49.
Abstract: The effect of electrical stimulation of cutaneous afferents in the superficial peroneal nerve on the locomotor discharges of single medial gastrocnemius gamma-motoneurones has been investigated in a decerebrate cat preparation. Units were classified as static (n=9) or dynamic (n=7) indirectly on the basis of their resting and locomotor discharge characteristics. Brief trains of stimulation, at 2 and 3xthreshold (T), were applied at rest and during locomotion. Responses were assessed by calculating the change in mean rate during the 100 ms after stimulus onset compared with a control period. At rest, static and dynamic gamma- motoneurones showed opposite responses. Static neurones were excited while inhibition was dominant with dynamic neurones. Effects were always present at 2T. During locomotion, inhibitory responses occurred with both types of gamma-motoneurone and excitation was not apparent. The inhibition of static neurones was maximum during (four units) or between (five units) EMG bursts and minimum in the opposite phase of EMG activity. For dynamic neurones, inhibition was not related to locomotor phase. Generally (six of seven units), the inhibition of dynamic gamma-motoneurones was reduced throughout the step cycle, including phases in which background discharge rates were comparable to resting levels. Latencies of response were measured from peristimulus time histograms. Subtraction of peripheral conduction times gave estimated central delays of locomotor inhibition for static (2.4+/-0.2 ms, n=6; mean+/-S.E.M.) and dynamic (2.2+/-0.2 ms, n=7) gamma- motoneurones that were not significantly different (P>0. 1) and are consistent with spinal oligosynaptic pathways. We conclude that low threshold skin afferents from the foot dorsum are capable of influencing both types of gamma-motoneurone during walking through short latency spinal inhibitory pathways. Further, a highly specific (reciprocal) control of the reflex responses of static and dynamic gamma-efferents occurs that is dependent upon behavioural context. The results are discussed in relation to cutaneous effects on gamma- motoneurones which are suggested to form an adaptive control system

Nene A.V. and Jennings S.J. (1989) Hybrid paraplegic locomotion with the ParaWalker using intramuscular stimulation: a single subject study. Paraplegia 27, 125-132.
Abstract: Functional intramuscular electrical stimulation of the gluteus maximus and gluteus medius on the stance side whilst walking is reported. The subject was an adult, male, post-traumatic complete paraplegic with lesion level at T7. He had been using surface stimulation to aid his walking with the adult ParaWalker Orthosis but suffered unpleasant anterior abdominal wall muscle contractions with high amplitude stimulation. The experimental use of percutaneous intramuscular Platinum/Iridium wire electrodes demonstrated that more forceful contractions of the buttock muscles could be achieved without any effect on abdominal wall musculature. This prompted the use of a permanent, implanted system. The system is inductively coupled to an external control device and is working satisfactorily 7 months after implantation

Nene A.V. and Patrick J.H. (1990) Energy cost of paraplegic locomotion using the ParaWalker--electrical stimulation "hybrid" orthosis. Arch. Phys. Med. Rehabil. 71, 116-120.
Abstract: In an adult paraplegic walking with the ParaWalker, electrical stimulation of the stance-side gluteal muscles (gluteus maximus and medius) reduces the force applied through the crutches during the gait cycle. In this study, five posttrauma, fully rehabilitated, complete paraplegic adult men walked using their ParaWalkers both without and with electrical stimulation augmentation. Oxygen consumption and distance covered during the test period were monitored to derive speed (m s-1), energy cost (J kg-1 m-1), and energy consumption (J kg-1 s-1). With the ParaWalker-electrical stimulation "hybrid" orthosis, three subjects increased their walking speed (10.92%, 7.85%, and 9.27%) and two reduced it (4.49% and 9.36%). Energy cost was reduced in four subjects (6.47%, 7.93%, 6.92%, and 7.97%) but remained the same for the fifth. Energy consumption was reduced in four subjects (0.82%, 11.06%, 0.38%, and 10.28%) and increased in one subject (4.19%). Results were better than those in a previous study of paraplegic locomotion using functional electrical stimulation and long-leg braces. Although electrical stimulation augmentation yields only a small reduction in energy cost, its long-term physiologic effect could be significant in increasing the aerobic-anaerobic threshold of an individual via recruitment of large muscles like the gluteus maximus and medius, thereby increasing performance in a sustained activity like walking

Noga B.R., Kettler J., and Jordan L.M. (1988) Locomotion produced in mesencephalic cats by injections of putative transmitter substances and antagonists into the medial reticular formation and the pontomedullary locomotor strip. J. Neurosci. 8, 2074-2086.
Abstract: The purpose of this study was to determine the distribution of cells in the medial reticular formation (MRF) and the pontomedullary locomotor strip (PLS), which can induce locomotion when activated. Controlled microinjections of neuroactive substances (Goodchild et al., 1982) into the MRF or PLS were made in order to activate cell bodies in those areas. The ability of trigeminal receptive field stimulation to induce locomotion before and after drug infusion into the PLS was also assessed since the PLS and the spinal nucleus of the trigeminal nerve are similar in their anatomical distribution. Experiments were performed on precollicular-postmamillary decerebrate cats walking on a treadmill. Injections of glutamic acid (GA; 500 nmol) into the MRF produced locomotion that was antagonized by infusion of glutamic acid diethyl ester into the same spot. Decreases in the current threshold for locomotion produced by electrical stimulation of the MRF were observed when the MRF was infused with either GA (40-80 nmol), DL- homocysteic acid (DL-HCA; 200 nmol), or picrotoxin (PIC; 15 nmol). Injections of GA (100 nmol), DL-HCA (700 nmol), PIC (10-50 nmol), and substance P (2 nmol) into the PLS also produced locomotion. Locomotion produced by injections of PIC into the PLS was blocked by infusion of equal amounts of muscimol or GABA. Effective PLS injection sites were all confined to the trigeminal spinal nucleus or immediately ventral and medial to this in the adjacent lateral reticular formation. Trigeminal nerve peripheral field stimulation evoked locomotion after microinjection of PIC into the PLS, although this same facial stimulus was not effective prior to drug injection. We conclude that the MRF and PLS regions of the cat brain stem contain cells that produce locomotion when chemically stimulated, and we suggest that the PLS is closely related to or synonymous with the spinal nucleus of the trigeminal nerve. Furthermore, we suggest that stimulation of trigeminal afferents is analogous to stimulation of segmental afferent pathways in the production of locomotion (Sherrington, 1910; Jankowska et al., 1967; Afelt, 1970; Budakova, 1972; Grillner and Zangger, 1979)

Ohnishi A., Yamamoto T., Izawa K., Yamamori S., Takahashi K., Mega H., and Jinnai K. (2000) Dejerine-sottas disease with a novel de novo dominant mutation, Ser 149 Arg, of the peripheral myelin protein 22. Acta Neuropathol. (Berl) 99, 327-330.
Abstract: The Ser149Arg mutation of peripheral myelin protein 22 (PMP22) was found in a 19-year-old woman with a sporadic case of Dejerine-Sottas disease. The patient showed delayed motor development. She walked for the first time with support at the age of 2 years. Scoliosis developed at age 4 years. Her walking ability was best at age 11. Thereafter, she showed progressive muscle weakness and sensory disturbances in the distal extremities. At the age of 18 years, the use of a wheelchair became necessary. Motor and sensory nerve conduction studies showed absent motor and sensory responses on electrical stimulation of the limb nerves. A sural nerve biopsy specimen showed marked decreases in the numbers of both large and small myelinated fibers, abundant onion- bulb formation, and hypomyelination. Electron microscopic observation revealed the presence of demyelinated axons and myelin sheaths disproportionately thin relative to axon diameter. That this was a de novo mutation was established by parentage testing and PMP22 gene analysis of the parents. The mutation seems to be novel and dominant

Patrick J.H. and McClelland M.R. (1985) Low energy cost reciprocal walking for the adult paraplegic. Paraplegia 23, 113-117.
Abstract: The hip guidance orthosis which allows paraplegic children to walk reciprocally has been further developed for adult traumatic paraplegics. Since December 1981, 11 adult complete paraplegics have walked using this device, designated a 'Parawalker'. Our understanding of the mechanics of this form of ambulation and our early work with functional electrical stimulation leave us hopeful of achieving a realistic goal for these patients

Pearson K.G., Misiaszek J.E., and Fouad K. (1998) Enhancement and resetting of locomotor activity by muscle afferents. Ann. N. Y. Acad. Sci. 860, 203-215.
Abstract: The generation of the normal motor pattern for walking in mammals requires feedback from muscle proprioceptors. Two characteristics of the motor pattern particularly dependent on proprioceptive signals are (1) the magnitude of activity in knee and ankle extensor muscles and (2) the duration of extensor bursts during stance. Sensory regulation of these characteristics ensures that the level of activity in extensor muscles during stance is appropriate for the load carried by the leg and that the swing phase is not initiated when a leg is loaded. Many different groups of afferents from flexor and extensor muscles can influence the locomotor pattern. Most attention has focused on the action of group I afferents from ankle extensors. Electrical stimulation of these afferents during extension increases the duration and the magnitude of extensor activity. The prolongation of extensor activity depends in part on excitation of the extensor half-center by group Ib afferents from Golgi tendon organs. The enhancement of the magnitude of extensor bursts is produced primarily via disynaptic and polysynaptic pathways opened only during locomotion. The involvement of the proprioceptive signals in the generation of locomotor activity means that the gains in reflex pathways must be constantly calibrated according to the biomechanical properties of the locomotor system. Alteration of these properties by weakening ankle extensor muscles has recently been found to produce compensatory changes in proprioceptive influences on the locomotor pattern

Peck B.K. and Vanderwolf C.H. (1991) Effects of raphe stimulation on hippocampal and neocortical activity and behaviour. Brain Res. 568, 244-252.
Abstract: In chronically prepared rats, electrical stimulation (100 Hz, 0.1 ms pulses) of the dorsal raphe nucleus, some sites in the median raphe nucleus, and adjoining regions of the midbrain produced locomotion accompanied by hippocampal rhythmical slow activity (RSA) and neocortical low voltage fast activity (LVFA). Both the behaviour and the cerebral waveforms persisted after injection of scopolamine HBr (5 mg/kg, s.c.). Median raphe stimulation usually produced behavioural freezing or an unnatural forced movement accompanied by RSA and LVFA. The behavioural response and the LVFA were not affected by scopolamine but scopolamine eliminated the RSA, replacing it with a low amplitude irregular (suppressed) pattern. p-Chlorophenylalanine (PCPA, 500 mg/kg/day x 3, i.p.) reduced the RSA and LVFA normally present during walking after scopolamine but did not reduce the hippocampal suppression produced by median raphe stimulation in scopolamine-treated rats. Hippocampal suppression and LVFA in response to median raphe stimulation were also present in urethane (1.0-1.5 g/kg, i.p.) anesthetized rats, whether pretreated with PCPA or not. Stimulation at most other midbrain sites produced RSA and LVFA in the urethane condition. RSA was abolished in the urethane plus scopolamine condition. The data support the view that scopolamine-resistant RSA and LVFA are dependent on serotonergic projections. The hippocampal suppression produced by median raphe stimulation may be dependent on non-serotonergic neurotransmission

Peckham P.H. and Creasey G.H. (1992) Neural prostheses: clinical applications of functional electrical stimulation in spinal cord injury. Paraplegia 30, 96-101.
Abstract: Function lost in spinal cord injury can be partially restored in some patients by electrical stimulation of remaining neurons. Neural prostheses designed for this purpose have been under development for several decades and are now in increasing clinical use. Applications are outlined for restoration of respiration, bladder, bowel and sexual function, exercise, hand grasp and standing and walking

Pedrinelli R., Marino L., Dell'Omo G., Siciliano G., and Rossi B. (1998) Altered surface myoelectric signals in peripheral vascular disease: correlations with muscle fiber composition. Muscle Nerve 21, 201-210.
Abstract: Conduction velocity (CV) and median frequency (MDF) during tetanic electrical stimulation of the tibialis anterior muscle were evaluated in patients with uncomplicated peripheral arterial occlusive disease. Results were analyzed with respect to biopsy determination of diameter and proportion of types 1 and 2 muscles fibers. Initial MDF and CV correlated positively with type 2, but not type 1 fiber diameter. Initial MDF was reduced bilaterally in patients with unilateral peripheral arterial occlusive disease as compared to normal subjects, indicating that chronic ischemia alone cannot explain the altered myoelectric signal. Physical training increased pain-free walking distance and raised initial MDF, though CV remained unchanged. Fatigue indices were highly interrelated, but showed no correlation with any of the other evaluation variables. Thus, initial MDF, a correlate of type 2 muscle fiber distribution in chronically ischemic tibialis anterior muscles, is altered in peripheral vascular disease. However, muscle ischemia alone cannot explain all aspects of this abnormality

Perry J., Waters R.L. (1975) Orthopaedic evaluation and treatment of the stroke patient. AAOS Instr Course Lect 24, 40-44.

Perry J., Waters R.L., Perrin T. (1978) Electromyographic analysis of equinovarus following stroke.  Clin Orthop Rel Res 131, 47-53.

Perry J., Giovan P., Harris L.J., Montgomery J., Azaria M. (1978) The determinants of muscle action in the hemiparetic lower extremity (and their effect on the examination procedure.) Clin Orthop Rel Res 131, 71-89.

Perry J., Easterday C.S., Antonelli D.J. (1981) Surface versus intramuscular electrodes for electromyography of superficial and deep muscles. Phys Ther 61, 7-15.

Perry J. (1988) The contribution of dynamic electromyography to gait analysis. In: Rehabilitation Research and Development Service [Ed]: Gait Analysis in the Science of Rehabilitation. Washington D.C., Department of Veterans Affairs, pp 33-48.

Perry J., (1992) Gait Analysis: Normal and Pathological Function.  Thorofare, NJ, Slack.

Perry J., Garrett M., Gronley J.K., Mulroy S.J. (1995) Classification of walking handicap in the stroke population. Stroke 26, 982-989.

Perry J. (1999) The use of gait analysis for surgical recommendations in traumatic brain injury. J Head Trauma Rehabil 14, 116-135.

Petersen N., Christensen L.O., and Nielsen J. (1998) The effect of transcranial magnetic stimulation on the soleus H reflex during human walking. J. Physiol 513 ( Pt 2), 599-610.
Abstract: 1. The effect of transcranial magnetic stimulation (TMS) on the soleus H reflex was investigated in the stance phase of walking in seventeen human subjects. For comparison, measurements were also made during quiet standing, matched tonic plantar flexion and matched dynamic plantar flexion. 2. During walking and dynamic plantar flexion subliminal (0.95 times threshold for a motor response in the soleus muscle) TMS evoked a large short-latency facilitation (onset at conditioning-test interval: -5 to -1 ms) of the H reflex followed by a later (onset at conditioning-test interval: 3-16 ms) long-lasting inhibition. In contrast, during standing and tonic plantar flexion the short-latency facilitation was either absent or small and the late inhibition was replaced by a long-lasting facilitation. 3. When grading the intensity of TMS it was found that the short-latency facilitation had a lower threshold during walking than during standing and tonic plantar flexion. Regardless of the stimulus intensity the late facilitation was never seen during walking and dynamic plantar flexion and the late inhibition was not seen, except for one subject, during standing and tonic plantar flexion. 4. A similar difference in the threshold of the short-latency facilitation between walking and standing was not observed when the magnetic stimulation was replaced by transcranial electrical stimulation. 5. The lower threshold of the short-latency facilitation evoked by magnetic but not electrical transcranial stimulation during walking compared with standing suggests that cortical cells with direct motoneuronal connections increase their excitability in relation to human walking. The significance of the differences in the late facilitatory and inhibitory effects during the different tasks is unclear

Petrofsky J.S. and Smith J.B. (1991) Physiologic costs of computer-controlled walking in persons with paraplegia using a reciprocating-gait orthosis. Arch. Phys. Med. Rehabil. 72, 890-896.
Abstract: Blood pressure, heart rate, oxygen uptake, cardiac output, and the surface electromyogram from key muscle groups in the upper body were measured in four subjects with paraplegia during ambulation using only a reciprocating-gait orthosis (RGO) and using an RGO with movement assisted by functional electrical stimulation (FES) of the hamstring and gluteus maximus muscles. These data were compared to data collected on four able-bodied control subjects during ambulation at matched speeds. Whether walking with FES and RGOs or walking with RGOs alone, subjects had an optimum gait speed at which efficiency was highest. For paralyzed subjects using FES, the optimum walking speed was approximately 1.5 mph (2.4km/hr); without FES, the optimum speed averaged about 0.75mph (1.2km/hr). Blood pressure, heart rate, oxygen uptake, and cardiac output were measured during ambulation with FES and were found to be higher than those of controls, but they were significantly lower than those in the paralyzed subjects in RGOs with no FES. Electromyogram studies showed that the activity in upper body muscles was much higher when walking in RGOs without FES than in RGOs with FES

Phillips C.A. (1989) Electrical muscle stimulation in combination with a reciprocating gait orthosis for ambulation by paraplegics. J. Biomed. Eng 11, 338-344.
Abstract: Commercially available electrical muscle stimulators (EMS) provide functional electrical stimulation and are interfaced with reciprocating gait orthosis (RGO). The system which has been developed is described here as an EMS-RGO. Advantages of the system include: medically prescriptable subsystems available from manufacturers, and commercially recommended subsystems for applications such as gait training. The system itself employs four EMS units worn on a belt. It is controlled by remote switches and is interfaced to electrodes placed over the quadriceps, hamstring and gluteal muscle groups of each leg. Two EMS units (for quadriceps stimulation) function primarily for stand-up and sit-down. Two other EMS units (for stimulation of the hip extensors) function primarily for ambulation. Each EMS unit is powered by a nine volt alkaline transistor battery which provides about 36 stand-uphs and sit-down's and approximately 3.1 km of walking before replacement is necessary. The system has been evaluated on a T-5 level paraplegic individual who sustained a motor complete lesion (Frankel Class B) of the spinal cord over seven years ago. It is emphasized that successful EMS-RGO walking exercise must be preceded by a physical conditioning programme of active physical therapy. New battery technology (such as lithium batteries) may improve the useful lifespan of the system, and new electrode technology (such as TTGs) may improve patient acceptance of the system

Phillips C.A. (1989) Functional electrical stimulation and lower extremity bracing for ambulation exercise of the spinal cord injured individual: a medically prescribed system. Phys. Ther. 69, 842-849.
Abstract: The purpose of this study was to determine whether commercially available electrical muscle stimulators could provide functional ambulation exercise for the spinal cord injured individual. Commercially available electrical muscle stimulators were used for functional electrical stimulation and interfaced with reciprocating gait orthoses so that a new system has been developed. Advantages of the system include commercially available subsystems and subsystems for applications such as gait training. The system involves six electrical stimulation units worn on a belt; controlled by remote switches; and interfacing to electrodes placed over the quadriceps femoris, hamstring, and gluteal muscle groups of each leg. Four electrical stimulation units (for quadriceps femoris muscle stimulation) function primarily for stand-up and sit-down activities. Two other units (for stimulation of the hip extensor muscles) function primarily for ambulation. The system is described for use with a C7-level quadriplegic individual. The patient successfully performed over 20 repetitions of stand-up and sit down exercises with the system. An average walking distance of about 0.8 km was routinely traversed at velocities ranging from 1.2 to 2.0 km per hour. It was concluded that muscle fatigue, rather than battery power, was the functionally limiting factor for the quadriplegic patient. A recommendation is that application of the system for walking exercise should be preceded by a physical conditioning program of functional electrical stimulation. Specific medical criteria should be satisfied prior to formally prescribing the system for an individual. Finally, the steps involved in the writing of the walking system prescription are outlined

Phillips C.A. and Hendershot D.M. (1991) A systems approach to medically prescribed functional electrical stimulation. Ambulation after spinal cord injury. Paraplegia 29, 505-513.
Abstract: A functional electrical stimulation (FES) system for ambulation of spinal cord injured patients has been described to consist of physician prescriptable, commercially available components. The system components are: electrical muscle stimulators, a reciprocating gait orthosis and the electrode delivery system. A systems approach to medically prescribed FES ambulation requires the interfacing of these basic components, each of which has the flexibility to adjust to the optimal configuration for each individual patient. The electrode delivery system is of central importance in interfacing the basic components. This report describes the electrode delivery system, a transcutaneous transducer garment, which allows a variety of electrode configurations and stimulation patterns. The system has been successfully employed on a C7 level tetraplegic patient and a T9 level paraplegic patient

Phillips C.A. and Hendershot D.M. (1991) Functional electrical stimulation and reciprocating gait orthosis for ambulation exercise in a tetraplegic patient: a case study. Paraplegia 29, 268-276.
Abstract: The purpose of this paper is to report the cardiopulmonary stresses (as indicated by heart rate, blood pressure, oxygen consumption and task cost) for a tetraplegic individual when walking with electrical stimulation and a gait orthosis as opposed to walking with a gait orthosis alone. Functional electrical stimulation (FES), when interfaced with a reciprocating gait orthosis (RGO), resulted in walking exercise for a C-7 level tetraplegic subject, who was 8 years post-injury. Cardiopulmonary measurements were made and task costs calculated on this individual during progressive velocity walking with the FES-RGO and the orthosis alone (without FES). Results for the tetraplegic individual indicate that there were no significant changes in heart rate at the various walking velocities with respect to the two systems. However, systolic blood pressure was significantly reduced at the three highest walking velocities (1.2, 1.6 and 2.0 kph) when using the FES and orthosis system as compared to orthosis-alone walking (p less than .025, p less than .005 and p less than .025 respectively). Calculated oxygen consumption was significantly reduced and calculated task cost improved at the highest walking velocity (2.0 kph) when using the FES-RGO system as compared to using only the RGO (p less than .025). It is concluded that cardiopulmonary stresses are significantly less for this tetraplegic individual when ambulating at the higher velocities with electrical stimulation and a gait orthosis than when walking with a gait orthosis alone. This may result in improved endurance during each walking session and (consequently) an improved aerobic exercise effect. This might also allow some tetraplegics, who would be unable to walk with the RGO alone, to walk with electrical stimulation and the RGO

Phillips C.A., Koubek R.J., and Hendershot D.M. (1991) Walking while using a sensory tactile feedback system: potential use with a functional electrical stimulation orthosis. J. Biomed. Eng 13, 91-96.
Abstract: A major limitation in the utilization of a functional electrical stimulation (FES) orthosis for routine, daily standing and walking of the spinal-cord-injured person is that visual monitoring is required to maintain balance and the walking pace. For standing and walking to be continuous and automatic with such an orthosis, a closed-loop sensory feedback system is proposed and evaluated; it provides vibrotactile feedback as a substitute to one's own visual sensation. Eight blindfolded experimental subjects were utilized as 'imitators' to interpret the footfalls of a second person (the pace setter). The experimental objective was to test the hypothesis that sufficient information could be transferred by way of the sensory (tactile) feedback system to the 'imitator' and to determine effectively foot position and anticipate the next step of the pacesetter. Quantitative analysis evaluated the effect of three different levels of training, under two different levels of cognitive load. The results disclosed a significant improvement in subject performance at the higher training levels compared with the 'no training' level (P = 0.01). Neither the cognitive load nor the interaction of training and cognitive load altered significantly the effect of training on subject performance. The experimental hypothesis is therefore satisfied that sufficient information was indeed transferred using the apparatus described. Such information (when utilized in conjunction with a thorough training programme) could be used in a practical sense by a paraplegic individual to interpret his own foot steps. Through continued use and training, it is likely that this information could become subconscious and automatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Pickar J.G., Hill J.M., and Kaufman M.P. (1993) Stimulation of vagal afferents inhibits locomotion in mesencephalic cats. J. Appl. Physiol 74, 103-110.
Abstract: Using electrical stimulation of the mesencephalic locomotor region, we made decerebrate unanesthetized cats walk on a treadmill. The locomotion induced by stimulation of this midbrain area was assessed before and during activation of vagal afferents by either intravenous injection of phenylbiguanide or inflation of a balloon placed in the left atrium. Inflation of a balloon, which increased left atrial pressure by 7-25 mmHg, abolished locomotion in 9 of 10 cats tested. Bilateral cervical vagotomy prevented the abolition of locomotion by balloon inflation in each of two cats tested. Intravenous phenylbiguanide (50 or 100 micrograms/kg) or serotonin (40 micrograms/kg) injections abolished or attenuated walking induced by midbrain stimulation in 11 of 13 cats tested. In addition, intravenous phenylbiguanide injections abolished or attenuated locomotion with a shorter onset time than did systemic injections of this substance in five of six cats tested. Bilateral cervical vagotomy prevented the abolition of locomotion by phenylbiguanide injection in each of five cats tested. We conclude that locomotion can be prevented by a viscerosomatic reflex arising from the lungs and heart. The afferent arm of this reflex arc is the vagus nerve. Afferents such as slowly and rapidly adapting pulmonary stretch receptors, atrial receptors, and lung C-fibers may have had a role in preventing locomotion during the increase in left atrial pressure in our experiments. On the other hand, pulmonary C-fibers had a crucial role in preventing locomotion during intravenous injection of phenyl-biguanide. We speculate that this viscerosomatic reflex may help to explain in part the intolerance for exercise displayed by patients with congestive heart failure

Pierrot-Deseilligny E. (1997) Assessing changes in presynaptic inhibition of Ia afferents during movement in humans. J. Neurosci. Methods 74, 189-199.
Abstract: Different methods, based on different principles, have been proposed to estimate changes in presynaptic inhibition of Ia terminals (accompanied by primary afferent depolarization, (PAD)) during voluntary contraction in humans. (i) A discrepancy between the H-reflex amplitude, at an equal level of EMG activity, in two situations (e.g., walking and standing) may be taken as suggesting a different control of PAD interneurones in the two cases. (ii) A conditioning stimulation (vibration or electrical stimulation) is used to activate PAD interneurones and to evoke presynaptic inhibition of the afferent volley of the test reflex. The resulting long-lasting depression of the reflex depends on the excitability of PAD interneurones, but can be contaminated by long-lasting post-synaptic effects. (iii) The amount of reflex facilitation evoked by a purely monosynaptic Ia volley varies inversely with the on-going presynaptic inhibition of Ia afferents mediating the conditioning volley, and can be used to assess this on- going presynaptic inhibition. None of these methods can provide by itself unequivocal evidence for a change in presynaptic inhibition of Ia terminals, but reasonably reliable interpretations may be proposed when congruent results are obtained with different methods. Thus it has been shown that, during selective voluntary contraction, presynaptic inhibition is decreased on Ia afferents projecting on motoneurones of the contracting muscle and increased on Ia afferents projecting on motor nuclei not involved in the contraction

Popovic D., Stein R.B., Oguztoreli N., Lebiedowska M., and Jonic S. (1999) Optimal control of walking with functional electrical stimulation: a computer simulation study. IEEE Trans. Rehabil. Eng 7, 69-79.
Abstract: Bipedal locomotion was simulated to generate a pattern of activating muscles for walking using electrical stimulation in persons with spinal cord injury (SCI) or stroke. The simulation presented in this study starts from a model of the body determined with user-specific parameters, individualized with respect to the lengths, masses, inertia, muscle and joint properties. The trajectory used for simulation was recorded from an able-bodied subject while walking with ankle-foot orthoses. A discrete mathematical model and dynamic programming were used to determine the optimal control. A cost function was selected as the sum of the squares of the tracking errors from the desired trajectories, and the weighted sum of the squares of agonist and antagonist activations of the muscle groups acting around the hip and knee joints. The aim of the simulation was to study plausible trajectories keeping in mind the limitations imposed by the spinal cord injury or stroke (e.g., spasticity, decreased range of movements in some joints, limited strength of paralyzed, externally activated muscles). If the muscles were capable of generating the movements required and the trajectory was achieved, then the simulation provided two kinds of information: 1) timing of the onset and offset of muscle activations with respect to the various gait events and 2) patterns of activation with respect to the maximum activation. These results are important for synthesizing a rule-based controller

Popovic D.B. (1993) Finite state model of locomotion for functional electrical stimulation systems. Prog. Brain Res. 97, 397-407.
Abstract: A finite state model of locomotion was developed to simplify a controller design for motor activities of handicapped humans. This paper presents a model developed for real time control of locomotion with functional electrical stimulation (FES) assistive systems. Hierarchical control of locomotion was adopted with three levels: voluntary, coordination and actuator level. This paper deals only with coordination level of control. In our previous studies we demonstrated that a skill-based expert system can be used for coordination level of control in multi-joint FES systems. Basic elements in this skill-based expert system are production rules. Production rules have the form of If-Then conditional expressions. A technique of automatic determination of these conditional expressions is presented in this paper. This technique for automatic synthesis of production rules uses fuzzy logic and artificial neural networks (ANN). The special class of fuzzy logic elements used in this research is called preferential neurons. The preferential neurons were used to estimate the relevance of each of the sensory inputs to the recognition of patterns defined as finite states. The combination of preferential neurons forms a preferential neural network. The preferential neural network belongs to a class of ANNs. The preferential neural network determined the set of finite states convenient for a skill-based expert system for different modalities of locomotion

Radil T., Snydrova I., Hacik L., Pfeiffer J., and Votava J. (1988) Attempts to influence movement disorders in hemiparetics. Scand. J. Rehabil. Med. Suppl 17, 157-161.
Abstract: Step duration, measured in hemiparetic patients walking on a circular path, showed that step duration of the affected foot is usually longer. Functional electrical stimulation of the peroneal nerve in the swing phase of the step (eliminating foot drop) shortened step duration in the majority of cases. Hypnosis induced by the verbal fixation technique was used in hemiparetic patients (a) to ascertain whether the patient's mobility would increase during hypnosis and to determine (in positive cases) whether this approach might be used to predicting the effect of rehabilitation performed by classical methods; (b) to use hypnosis as a method of auxiliary treatment. The general finding was that the extent of movements of the hemiparetic upper extremity considerably improved during and immediately after hypnosis. This effect could be observed both at the level of severe impairment (at the beginning of treatment) and during the later stages when mobility greatly improved due to rehabilitation and recovery

Reese T., Porszasz R., Baumann D., Bochelen D., Boumezbeur F., McAllister K.H., Sauter A., Bjelke B., and Rudin M. (2000) Cytoprotection does not preserve brain functionality in rats during the acute post-stroke phase despite evidence of non-infarction provided by MRI. NMR Biomed. 13, 361-370.
Abstract: In animal models of stroke the promise of a therapy is commonly judged from infarct size measurements, assuming that a reduction in infarct size results in reduction of the functional deficits. We have evaluated the validity of the concept that structural integrity translates into functional integrity during the acute post-stroke period (24 h). Unilateral permanent middle cerebral artery occlusion (pMCAO) in Fischer F344 rats leads to infarcts comprising the ipsilateral striatum and cortical structures, including the somatosensory cortex. Infarct volumes were assessed using magnetic resonance imaging (MRI) methods (T(2), diffusion, perfusion MRI). The functional integrity of the somatosensory cortex was assessed by functional MRI (fMRI) measuring changes in local cerebral blood volume, and by assessing the forelimb grip strength and the beam-walking performance of the animals. Treatment with the calcium antagonist isradipine (2.5 mg/kg injected s.c. immediately after pMCAO) reduced the total infarct size by more than 40% compared to vehicle-injected controls. In particular, the ipsilateral somatosensory cortex appeared normal in diffu

Rizzo M., Betz R.R., Mulcahey M.J., and Smith B.T. (1998) Magnetic resonance imaging data in the evaluation of effects of functional electrical stimulation on knee joints of adolescents with spinal cord injury. J. Spinal Cord. Med. 21, 124-130.
Abstract: Diagnostic imaging, consisting of roentgenograms and magnetic resonance images (MRIs), was performed as part of an evaluation of the effects of a functional electrical stimulation (FES) program on the knee joints of 29 adolescents with spinal cord injuries following implantation of fine- wire intramuscular electrodes in their lower extremity muscles. The subjects underwent a regimen consisting of stimulated exercise, standing and/or walking. The effects of FES on knee joints were prospectively studied by reviewing diagnostic imaging data. Evaluation of MRIs and plain radiographs showed no evidence of knee joint pathology secondary to FES exercise or weight bearing. In fact, based on follow-up of MRI scan, many of the joints improved following participation in the program. The MRI data supported the clinical examination of the knee joints of these children. Clinical examination appears adequate for screening for potential knee joint problems

Robinson T.E. and Green D.J. (1980) Effects of hemicholinium-3 and choline on hippocampal electrical activity during immobility vs. movement. Electroencephalogr. Clin. Neurophysiol. 50, 314-323.
Abstract: Earlier studies have shown that the hippocampal rhythmical slow activity (RSA or theta) which may occur during behavioral immobility (IRSA) is abolished by systemically administered atropine (is atropine- sensitive), although the RSA which accompanies movements, such as walking, running or swimming (MRSA) is atropine-resistant. This study was designed to manipulate brain cholinergic activity in ways other than through the use of postsynaptic receptor antagonists, and to determine the effects of such manipulations on IRSA and MRSA. The IRSA elicited by electrical stimulation of the reticular formation in urethanized rats was severely attenuated by intraventricular injections of hemicholinium-3 (HC-3), a drug which depletes brain acetylcholine. A subsequent systemic injection of choline chloride restored IRSA elicited by electrical stimulation. In contrast, HC-3 had no deleterious effects on the MRSA recorded from freely moving rats. Therefore, atropine-sensitive IRSA is also HC-3 sensitive, and atropine- resistant MRSA is also HC-3 resistant. These results support the hypothesis that there are two pharmacologically distinct neurochemical systems which may produce hippocampal RSA. It is suggested that acetylcholine is necessary for the production of IRSA, but is not necessary for the production of MRSA

Rossignol S., Chau C., Brustein E., Belanger M., Barbeau H., and Drew T. (1996) Locomotor capacities after complete and partial lesions of the spinal cord. Acta Neurobiol. Exp. (Warsz. ) 56, 449-463.
Abstract: This paper first reviews some of the observations made on the locomotor capabilities of several animal species with a special emphasis on cats and including primates and man after complete spinal lesions. We show that animals can perform well-coordinated walking movements of the hindlimbs when they are placed on a treadmill belt and this locomotion is also adaptable to speed and perturbations. Cats with partial spinal lesions of the ventral and ventrolateral parts of the cord can perform voluntary quadrupedal locomotion overground or on the treadmill albeit with deficits in weight support and interlimb coordination. We also show that some drugs such as clonidine (an alpha-2 noradrenergic agonist) can be used to trigger locomotion in early-spinal cats and discuss the effects of various neurotransmitter systems on the expression of the locomotor pattern in both complete and partial spinal cats. It is concluded that a pharmacological approach could be used, in combination with other approaches, such as locomotor training and functional electrical stimulation, to improve locomotor functions after spinal cord injuries in humans

Saito T., Nishioka M., Ogino M., Endo K., and Kowa H. (1993) [A case of hereditary motor and sensory neuropathy type I with optic atrophy, neural deafness and pyramidal tract signs]. Rinsho Shinkeigaku 33, 519-524.
Abstract: A case of hereditary motor and sensory neuropathy (HMSN) type I with optic atrophy, neural deafness and pyramidal tract signs was described. The patient was a 53-year-old man who had suffered from difficulty in walking, decreased visual acuity since age 16 years. These symptoms were slowly progressive. At the age of 37, he was pointed out optic atrophy, positive pyramidal tract signs. Distal muscle weakness with atrophy of four limbs was prominent at the age of 50. Since then, he noticed progressive hearing loss with blindness. His elder sister was diagnosed Charcot-Marie-Tooth disease. On neurological examination, he showed to have optic atrophy without retinitis pigmentosa and neural deafness. Also he showed mild degree of muscle weakness and atrophy in four limbs, severe in the distal part of lower limbs. Deep tendon reflexes were absent in all limbs with right Babinski sign. Superficial sensation was decreased slightly in the distal parts of four limbs. Deep sensation was markedly decreased in the leg. There were no cerebellar signs. Audiometric examination revealed bilateral neural hearing loss. There were no findings of spinal cord compression on spinal MRI. On the nerve conduction studies, sensory nerve action potential was not elicited in all nerves tested. Motor nerve conduction velocity of the right median was 41.1 M/sec, also ulnar nerve 44.7 M/sec, but M-wave was not elicited with the electrical stimulation of other tested nerves. On sural nerve biopsy, the density of myelinated fibers was severely decreased. Well-myelinated axon surrounded by onion bulb formation was observed in electron microscopic examination.(ABSTRACT TRUNCATED AT 250 WORDS)

Sander H.W., Masdeu J.C., Tavoulareas G., Walters A., Zimmerman T., and Chokroverty S. (1998) Orthostatic tremor: an electrophysiological analysis. Mov Disord. 13, 735-738.
Abstract: Orthostatic tremor (OT) is a clinically defined syndrome of leg tremor while standing. Controversy surrounds whether OT is a distinct syndrome or is an essential tremor (ET) variant. We report two patients with OT. Electrophysiological testing included polymyography, accelerometry, nerve conduction, and evoked potential studies. The effects of various maneuvers and body positions on the tremor were assessed. The findings included rapid (15-17 Hz) lower-extremity tremor burst frequency evoked by standing but not by walking or swaying; rapid upper-extremity burst pattern synchronous with lower-extremity bursts; and failure of electrical stimulation or mental concentration to "reset" the tremor. Additionally, there was the novel finding of accelerometric recordings in the legs revealing the same rapid frequency (16-17 Hz) as the electromyographic tremor bursts. Some prior reports have suggested that OT is related to ET by emphasizing a considerable disparity and variability between the accelerometric tremor frequency and the electromyographic burst frequency. In our patients, however, the rapid (15-17 Hz) accelerometer-recorded tremor synchronous with the electromyographic bursts, and also the clinical improvement with clonazepam but not beta blockers or mysoline, and the lack of a family history of ET provide support that OT is distinct from ET

Schmitz J., Buschges A., and Kittmann R. (1991) Intracellular recordings from nonspiking interneurons in a semiintact, tethered walking insect. J. Neurobiol. 22, 907-921.
Abstract: Nonspiking interneurons were investigated in a tethered, walking insect, Carausius morosus, that was able to freely perform walking movements. Experiments were carried out with animals walking on a lightweight, double-wheel treadmill. Although the animal was opened dorsally, the walking system was left intact. Intracellular recordings were obtained from the dorsal posterior neuropil of the mesothoracic ganglion. Nonspiking interneurons, in which modulations of the membrane potential were correlated with the walking rhythm, were described physiologically and stained with Lucifer Yellow. Interneurons are demonstrated in which membrane potential oscillations mirror the leg position or show correlation with the motoneuronal activity of the protractor and retractor coxae muscles during walking. Other interneurons showed distinct hyperpolarizations at certain important trigger points in the step cycle, for example, at the extreme posterior position. Through electrical stimulation of single, nonspiking interneurons during walking, the motoneuronal activity in two antagonistic muscles--protractor and retractor coxae--could be reversed and even the movement of the ipsilateral leg could be influenced. The nonspiking interneurons described appear to be important premotor elements involved in walking. They receive, integrate, and process information from different leg proprioceptors and drive groups of leg motoneurons during walking

Schumacher S., Bross S., Scheepe J.R., Seif C., Junemann K.P., and Alken P. (1999) Extradural cold block for selective neurostimulation of the bladder: development of a new technique. J. Urol. 161, 950-954.
Abstract: PURPOSE: Cryotechnique for selective block of the urethral sphincter and simultaneous activation of the bladder was developed to achieve physiological micturition during sacral anterior root stimulation (SARS). MATERIALS AND METHODS: In ten foxhounds SARS of S2 was carried out while extradurally both spinal nerves S2 were cooled down from positive 25C in a stepwise fashion until a sphincter block was observed. Subsequently, SARS of S2 was performed while the pudendal nerves were cooled down from + 15C. The effects of spinal and pudendal nerve cold block on the urethral sphincter and bladder during SARS and the recovery time were monitored by urodynamic investigation. RESULTS: A complete cold block of the urethral sphincter during spinal nerve cooling was achieved in all cases. During pudendal nerve cooling, the sphincter was completely blocked in two, and incompletely blocked in four dogs. Cold block temperature of the spinal nerves averaged +11.7C and of the pudendal nerves +6.2C. During SARS and spinal nerve cooling, an increase in intravesical pressure up to 13 cm. water was recognized, and recovery time was on average 6.6 minutes. Intravesical pressure remained unchanged during pudendal nerve cooling, with recovery time being less than 1 minute. The cold block was always reversible. CONCLUSIONS: Cryotechnique is an excellent method for selective and reversible block of the urethral sphincter during SARS to avoid detrusor-sphincter-dyssynergia. The application of cryotechnique in functional electrical stimulation leads to an improvement of quality of life in

Schumacher S., Scheepe J.R., Bross S., Bohler G., Alken P., Muller S.C., and Junemann K.P. (1999) Sacral anterior root stimulation and cryotechnique: A new option for selective urethral sphincter block and reversible deafferentation in the future? Arch. Physiol Biochem. 107, 242-247.
Abstract: A possible application of cryotechnique might be a selective block of nerve fiber activity during sacral anterior root stimulation to achieve selective block of urethral sphincter and reversible deafferentation. In 13 foxhounds, electrical stimulation of sacral anterior roots S2 was performed while the accompanying spinal nerves were simultaneously cooled down from +25 degrees C in a stepwise fashion until a block of urethral sphincter activity was observed. The effects of cold block on the urethral sphincter and bladder were monitored by urodynamic investigation. In 2 additional dogs sacral posterior roots S2 were cooled down to +3 degrees C while accompanying anterior and posterior roots were stimulated distal to the cryothermode. Compound action potentials (APs) were registered proximal to the cryothermode before, during and after cooling and recovery time of cold blocked nerves was evaluated. Complete cold block of the urethral sphincter during spinal nerve cooling was achieved in all cases. Block temperature averaged +12 degrees C. Detrusor pressure was a mean 5,2 cm water. Recovery time was on average 5 min. The cold block was always reversible. In both dogs of the second series the compound action potentials disappeared nearly completely at +3 degrees C. Three min after the end of the cooling period the appearance of the compound action potentials was back to normal. In this study, cryotechnique proved to be effective for selective and reversible block of nerve fibers during sacral anterior root stimulation. In functional electrical stimulation this technique may lead to an improvement of quality of life in

Sepulveda F., Granat M.H., and Cliquet A., Jr. (1997) Two artificial neural systems for generation of gait swing by means of neuromuscular electrical stimulation. Med. Eng Phys. 19, 21-28.
Abstract: A three-layer artificial neural network was used for adaptive control of gait swing generated by neuromuscular electrical stimulation (NMES) in a spinal cord injured subject. Network inputs consisted of knee and ankle goniometer signals for System 1, and knee and hip angular data for System 2. Controller output was proportional to changes in applied NMES pulse width (PW). Stimulation was applied to the left femoral and common peroneal nerves. The neural networks were trained off-line and on-line. Network performance was assessed by applying a number of different stimulation PWs and later comparing the resulting motion to a sample good step observed during the same test session. On-line training consisted of negative and positive reinforcement applied at chosen times. Both on-line and off-line training algorithms consisted of an enhanced supervised backpropagation scheme. Performance evaluation results favour the use of System 1 over System 2. Also, a network trained off-line and later submitted to on-line punishment appears to be more reliable (in automatic mode) than the same network after it is submitted to on-line reward or to off-line training alone. Finally, the systems' immediate response to on-line learning was favourable in all cases. Based on the results, a version of System 1 was used to generate walking in the test subject. This test indicated that the system is promising

Sharma M., Marsolais E.B., Polando G., Triolo R.J., Davis J.A., Jr., Bhadra N., and Uhlir J.P. (1998) Implantation of a 16-channel functional electrical stimulation walking system. Clin. Orthop. 236-242.
Abstract: A 16-channel electrical stimulation system was implanted in a 39-year- old patient with T10 paraplegia to restore sit to stand, walking, and exercise functions. System implantation required two surgical sessions. In the first session, the posterior muscle set consisting of bilateral semimembranosus, adductor magnus, and gluteus maximus muscles were exposed and epimysial electrodes sutured at the point of greatest muscle contraction. Closed double helix intramuscular electrodes were implanted in the erector spinae. Two weeks later, epimysial electrodes were attached to the eight anterior muscles consisting of the tibialis anterior, sartorius, tensor fasciae latae, and vastus lateralis with all 16 electrode leads passed to the anterior abdominal wall. The electrodes were connected to two eight-channel stimulators placed in the iliac fossae, and the system was checked by activating the individual muscles. The implanted stimulators received stimulation instructions and power via a radio frequency link to an external control. Stimulation patterns for standing, walking, sitting, and exercise functions were chosen from a preprogrammed menu via a finger key pad. After 3 weeks of restricted patient activity, all electrodes stimulated either the target muscle or had an acceptable spillover pattern. The patient is undergoing a 16-week rehabilitation course of stimulated exercises gradually increasing in intensity. At the conclusion, the goal is to discharge the patient with the system for spontaneous use. Although long term followup is required to determine system reliability, preliminary clinical results indicate that targeted, repeatable, functional muscle contractions in the lower extremity can be achieved with a system consisting of epimysial electrodes

Shik M.L., Severin F.V., and Orlovsky G.N. (1969) Control of walking and running by means of electrical stimulation of the mesencephalon. Electroencephalogr. Clin. Neurophysiol. 26, 549.

Shimada Y., Sato K., Abe E., Kagaya H., Ebata K., Oba M., and Sato M. (1996) Clinical experience of functional electrical stimulation in complete paraplegia. Spinal Cord. 34, 615-619.
Abstract: Percutaneous intramuscular electrodes and a portable multichannel system were used to restore the function of the paralyzed lower extremities in six patients with complete paraplegia. The total number of inserted electrodes was 168. All of the patients could stand, two could walk in parallel bars, and two could walk with a walker. The rate of breakage of electrodes was only 0.6% in our series. There were 10 (6.0%) superficial infections, and 10 (6.0%) movement of electrodes which required reimplantation. The results suggest that the ultrafine intramuscular electrode is practical for long term use with paraplegic patients. Although the system can be used for paraplegic patients during the activities of daily living, it will be necessary to develop a closed-loop controller to reduce the amount of stimulation to the extensor muscles and extend the endurance of upright activity to reduce fatigue

Snyder-Mackler L., Ladin Z., Schepsis A.A., and Young J.C. (1991) Electrical stimulation of the thigh muscles after reconstruction of the anterior cruciate ligament. Effects of electrically elicited contraction of the quadriceps femoris and hamstring muscles on gait and on strength of the thigh muscles. J. Bone Joint Surg. Am. 73, 1025-1036.
Abstract: The effects of neuromuscular electrical stimulation on the strength of the thigh muscles and on gait were examined in ten patients after reconstruction of the anterior cruciate ligament. The patients were randomly assigned to one of two treatment groups: neuromuscular electrical stimulation and volitional exercise, or volitional exercise alone. A four-week course of electrically elicited co-contraction of the thigh muscles resulted in significant attenuation of the characteristic loss of strength of the quadriceps as compared with volitional exercise. There was no significant difference between groups in any measure of performance of the hamstring muscles. In the group that received neuromuscular electrical stimulation, the values for cadence, walking velocity, stance time of the involved limb, and flexion-excursion of the knee during stance were significantly different from those of the volitional exercise group. Flexion- excursion of the knee during stance was directly and significantly correlated with strength of the quadriceps femoris muscle. Flexion of the knee during stance was qualitatively different in the involved extremity as compared with the uninvolved extremity in all patients. There is a rapid flexion of the knee at weight acceptance that is maintained throughout stance and probably reflects stabilization of the joint by muscular coactivation to compensate for weakness of the quadriceps. The patients who received neuromuscular electrical stimulation had stronger quadriceps muscles and more normal gait patterns than those in the volitional exercise group

Solomonow M., Aguilar E., Reisin E., Baratta R.V., Best R., Coetzee T., and D'Ambrosia R. (1997) Reciprocating gait orthosis powered with electrical muscle stimulation (RGO II). Part I: Performance evaluation of 70 paraplegic patients. Orthopedics 20, 315-324.
Abstract: Seventy paraplegics were fitted with an improved Reciprocating Gait Orthosis powered with or without (low-level injury) electrical stimulation of the thigh muscles (RGO II) as a secondary rehabilitation phase after the acute period. The patients comprised a broad cross- section of the paraplegic population applying for medical services and varied in age from 16 to 55 years, time since injury ranging from less than 1 to 15 years, injury levels ranging from C-6/7 to T-11/12, and varying levels of spasticity, contractures, scoliosis and other related medical and physiologic problems. The success/failure ratio was dependent on the injury level, which was 1:1 for paraplegics with injury level at C-6/7; 1.67:1 for those with injury of T-1/3; and about 4:1 for paraplegics with injury level from T-3 to T-12. Lack of motivation and medical problems unrelated to the RGO II treatment were the primary reasons for failure. The duration of treatment (outpatient service three times per week) ranged from 2 to 48 weeks (mean: 16). Forty-one patients who completed the RGO II rehabilitation and were sent home with the orthosis for independent use (for at least 6 months and up to 3 years) were surveyed by a staff member for analysis of the meaning and impact of the RGO II on the patient's life and health, and potential problems. It was shown that 80.5% of the 41 patients were regular users and 19.5% were non-users. Thirty-eight of the 41 patients declined an offer to return the RGO II equipment for a full refund, while three patients were willing to return the orthosis. It was concluded that the RGO II is viable orthosis for restoring standing and limited walking in paraplegics while providing sufficient function, safety, and reliability. The most appropriate patients for the use of such an orthosis consist primarily of those with T-3 to T-12 injury level and good motivation, although highly selected patients with higher injury levels also can benefit from its use. Regular use of the RGO II, even for exercise only, had a general positive impact on the patients' health and outlook

Stallard J. and Major R.E. (1995) The influence of orthosis stiffness on paraplegic ambulation and its implications for functional electrical stimulation (FES) walking systems. Prosthet. Orthot. Int. 19, 108-114.
Abstract: This study examines the evidence which supports the importance of maintaining relative abduction for effective reciprocal walking in high level paraplegic patients. In comparisons of orthoses, where this can only be achieved mechanically, those with higher lateral rigidity consistently showed greater levels of walking efficiency. The influence on hybrid systems of functional electrical stimulation (FES) of the gluteal muscles, where the primary function is to maintain abduction, also showed reductions in overall energy cost, reductions in upper limb effort, or both. Examination of the effect of increasing lateral rigidity of a purely mechanical orthosis by 10% showed that significant energy cost reductions were achieved (30% reduction in Physiological Cost Index) for patients with thoracic lesions experienced in reciprocal walking. A review of FES research suggested that for the modern healthcare sector the cost effectiveness of purely mechanical systems make them an attractive means of routinely providing the functional and therapeutic benefits of walking for high level paraplegic patients. In the prevailing climate of strict budgetry control a case is made for concentrating more research resources on improving still further walking efficiency, and resolving the outstanding problems of functionality and cosmesis in such systems for reciprocal walking

Stanic U., Acimovic-Janezic R., Gros N., Trnkoczy A., Bajd T., Kljajic M. (1978) Multichannel electrical stimulation for correction of hemiplegic gait. Scand J Rehabil Med 10, 75-92.

Stanic U., Acimovic-Janezic R., Gros N., Kljajic M., Malezic M., Bogataj V., Rozman J. (1991) Functional electrical stimulation in lower extremity-orthoses in hemiplegia. J Nerve Rehab 182, 23-35.

Stein R.B. (1999) Functional electrical stimulation after spinal cord injury. J. Neurotrauma 16, 713-717.
Abstract: This article reviews work mainly from my own laboratory on the effects of electrical stimulation for therapy and function following spinal cord injury. One to two hours per day of intermittent stimulation can increase muscle strength and endurance and also reverse some of the osteoporosis in bones that are stressed by the stimulation. Stimulation during walking can also be used to improve speed and other parameters of the gait. Surface stimulation systems with 1-4 channels of stimulation were used in a multicenter study. Initial increases of almost 20% in walking speed were seen and overall increases of nearly 50% in subjects who continued to receive stimulation for a year on average. Some changes were due to improved strength and coordination with stimulation and additional walking, but a specific effect of stimulation persisted throughout the trial. Improved devices will soon be available commercially that were developed on the basis of feedback from users

Strange K.D. and Hoffer J.A. (1999) Gait phase information provided by sensory nerve activity during walking: applicability as state controller feedback for FES. IEEE Trans. Biomed. Eng 46, 797-809.
Abstract: In this study, we extracted gait-phase information from natural sensory nerve signals of primarily cutaneous origin recorded in the forelimbs of cats during walking on a motorized treadmill. Nerve signals were recorded in seven cats using nerve cuff or patch electrodes chronically implanted on the median, ulnar, and/or radial nerves. Features in the electroneurograms that were related to paw contact and lift-off were extracted by threshold detection. For four cats, a state controller model used information from two nerves (either median and radial, or ulnar and radial) to predict the timing of palmaris longus activity during walking. When fixed thresholds were used across a variety of walking conditions, the model predicted the timing of EMG activity with a high degree of accuracy (average error = 7.8%, standard deviation = 3.0%, n = 14). When thresholds were optimized for each condition, predictions were further improved (average error = 5.5%, standard deviation = 2.3%, n = 14). The overall accuracy with which EMG timing information could be predicted using signals from two cutaneous nerves for two constant walking speeds and three treadmill inclinations for four cats suggests that natural sensory signals may be implemented as a reliable source of feedback for closed-loop control of functional electrical stimulation (FES)

Strange K.D. and Hoffer J.A. (1999) Restoration of use of paralyzed limb muscles using sensory nerve signals for state control of FES-assisted walking. IEEE Trans. Rehabil. Eng 7, 289-300.
Abstract: A real-time functional electrical stimulation (FES) state controller was designed that utilized sensory nerve cuff signals from the cat forelimb to control the timing of stimulation of the Palmaris Longus (PalL) muscle during walking on the treadmill. Sensory nerve signals from the median and superficial radial nerves provided accurate, reliable feedback related to foot contact and lift-off which, when analyzed with single threshold Schmitt triggers, produced valuable state information about the step cycle. The study involved three experiments: prediction of the timing of muscle activity in an open- loop configuration with no stimulation, prediction of the timing of muscle activity in a closed-loop configuration that included stimulation of the muscle over natural PaIL electromyogram (EMG), and temporary paralysis of selected forelimb muscles coupled with the use of the state controller to stimulate the PalL in order to return partial support function to the anesthetized limb. The FES state controller was tested in a variety of walking conditions, including different treadmill speeds and slopes. The results obtained in these experiments demonstrate that nerve cuff signals can provide a useful source of feedback to FES systems for control of limb function

Strojnik P., Acimovic-Janezic R., Vavken E., Simic V., Stanic U. (1987) Treatment of drop foot using an implantable peroneal underknee stimulator. Scand J Rehabil Med 19, 37-43.

Subbarao J.V. (1991) Walking after spinal cord injury. Goal or wish? West J. Med. 154, 612-614.
Abstract: Less than a third of patients walk again after a spinal cord injury, whereas every one of them wants to try. Residual function, energy expenditure, the extent of orthotic support needed, and patient motivation will determine the outcome. Functional electrical stimulation and other new orthotic designs have not notably increased the number of persons able to walk after a spinal injury. Rehabilitation professionals can use patient education, illustrating relearning to walk with examples of infants' and toddlers' progress, to assist patients in understanding their abilities and limitations. The final decision on ambulation and orthotic prescriptions can be made in stages after a patient adjusts to a wheelchair-independent level

Sunakawa M., Kohmoto T., and Komoto Y. (1989) Evaluation of tissue perfusion in ischemic legs of dogs by CO2 clearance rate. Acta Med. Okayama 43, 47-54.
Abstract: Improvement in tissue perfusion following surgically induced ischemia in limbs of dogs was experimentally evaluated to clarify the improvement of hemodynamics following walking exercise in chronic, peripheral arterial occlusive diseases. With the use of a computer system in conjunction with medical mass spectrometry, the local tissue perfusion rate was calculated on the basis of the clearance curve of tissue partial pressure of CO2 following electrical stimulation of the ischemic leg to simulate exercise. Ischemia was created in the leg by ligation of the proximal and peripheral arteries. In one month, intermittent claudication improved in accordance with improvement in muscle tissue perfusion. Angiographic evidence of distal runoff became visible six months after surgery, indicating that tissue perfusion played an important role in peripheral hemodynamics. The local tissue perfusion rate improved from 9.51 +/- 2.62 ml/100 g/min to 12.41 +/- 2.42 in one month, to 14.59 +/- 3.19 in three months, to 15.11 +/- 3.24 in six months and to 17.19 +/- 2.63 in twelve months. The improvement of ischemic symptoms following long-term exercise is attributed to improvements in tissue perfusion or collateral circulation

Svantesson U., Takahashi H., Carlsson U., Danielsson A., and Sunnerhagen K.S. (2000) Muscle and tendon stiffness in patients with upper motor neuron lesion following a stroke. Eur. J. Appl. Physiol 82, 275-279.
Abstract: The objective of this study was to investigate muscle and tendon stiffness in the triceps surae muscles in patients who had previously had a stroke. The participants were 12 men showing slight to moderate degrees of muscle tonus in the affected leg. All patients showed minimal or no overt clinical motor symptoms, and all walked without mechanical aid. Muscle strengths in isometric and isokinetic activities were measured, as was passive resistance during plantarflexion in each leg. Walking speed was also measured. Evaluations of physical performance and muscle tone were made. Muscle and tendon stiffness was calculated from measurements whilst passively stretching during electrical stimulation, separately for each leg. Muscle strength was significantly higher in the non-affected than in the affected leg. Muscle stiffness was significantly higher in the affected leg than in the non-affected leg. Tendon stiffness was significantly higher in the non-affected than in the affected leg. The higher muscle stiffness in the affected leg might enhance the possibility for storing elastic energy during preactivation. Lower tendon stiffness in the affected leg might reduce the development of fatigue in movements at low velocities

Sykes L., Campbell I.G., Powell E.S., Ross E.R., and Edwards J. (1996) Energy expenditure of walking for adult patients with spinal cord lesions using the reciprocating gait orthosis and functional electrical stimulation. Spinal Cord. 34, 659-665.
Abstract: A major factor influencing compliance with walking orthoses following spinal cord damage, is the energy requirement associated with them. We compared ambulatory energy expenditure in subjects using the reciprocating gait orthosis (RGO) with and without functional electrical stimulation (FES) of the thigh muscles at self selected walking speeds. Five adult subjects (median age 34 years, range 24-37) with spinal cord lesions ranging from C2 (incomplete) to T6 volunteered to participate in this study. All subjects were successful RGO users (median use 5.7 years, range 4.1-7.3). Walking speed (m/s), ambulatory energy consumption (J/kg/s) and energy cost (J/kg/m) were derived from oxygen uptake determined using the Douglas bag technique. We anticipated that subjects walking with FES would either: (a) walk at the same speed but reduce their energy cost or (b) increase their walking speed for the same (or less) energy cost. Walking speed and energy cost remained unchanged in one subject. One subject increased his walking speed by 14.0% and increased his energy consumption by 8.4%. His energy cost remained unchanged. Three subjects increased their walking speeds (by 12.4, 12.7 and 6.8%), energy consumption (by 25.9, 20.4 and 18.4% respectively) and energy cost (by 11.6, 6.8 and 10.5% respectively). We did not find a substantial benefit, in terms of energy expenditure, from the hybrid system when walking continuously for 5 min. We suggest that the hybrid system may be of greater benefit during prolonged walking, although other limitations, inherent in the RGO itself, may prevent an increase in compliance. Repetition of walking speed tests supported the reliability of our results. Tests on comparably aged, able-bodied subjects showed that an increase in energy cost of up to 5.8% was within the biological variability of the subject and the error of the methodology

Taylor P.N., Burridge J.H., Dunkerley A.L., Wood D.E., Norton J.A., Singleton C., and Swain I.D. (1999) Clinical use of the Odstock dropped foot stimulator: its effect on the speed and effort of walking. Arch. Phys. Med. Rehabil. 80, 1577-1583.
Abstract: OBJECTIVE: To assess the clinical effectiveness of the Odstock dropped foot stimulator by analysis of its effect on physiological cost index (PCI) and speed of walking. This functional electrical stimulation (FES) device stimulates the common peroneal nerve during the swing phase of gait. DESIGN: A retrospective study of patients who had used the device for 4 1/2 months. SUBJECTS: One hundred fifty-one patients with a dropped foot resulting from an upper motor neuron lesion. SETTING: A medical physics and biomedical engineering department of a district general hospital specializing in the clinical application of FES and a neurophysiotherapy department at a separate hospital. MAIN OUTCOME MEASURES: Changes in walking speed and effort of walking, as measured by PCI over a 10-meter course. RESULTS: There was a 92.7% compliance with treatment. Stroke patients showed a mean increase in walking speed of 27% (p<.01) and reduction in PCI of 31% (p<.01) with stimulation, and changes of 14% (p<.01) and 19% (p<.01), respectively, while not using the stimulator. Multiple sclerosis patients gained similar orthotic benefit but no "carry-over." CONCLUSIONS: The measured differences in walking with and without stimulation were statistically significant in the stroke and multiple sclerosis groups. In this study use of the stimulator improved walking. Those with stroke demonstrated a short-term "carry-over" effect

Taylor P.N., Burridge J.H., Dunkerley A.L., Lamb A., Wood D.E., Norton J.A., and Swain I.D. (1999) Patients' perceptions of the Odstock Dropped Foot Stimulator (ODFS). Clin. Rehabil. 13, 439-446.
Abstract: OBJECTIVE: To determine the perceived benefit, pattern and problems of use of the Odstock Dropped Foot Stimulator (ODFS) and the users' opinion of the service provided. DESIGN: Questionnaire sent in a single mailshot to current and past users of the ODFS. Returns were sent anonymously. SETTING: Outpatient-based clinical service. SUBJECTS: One hundred and sixty-eight current and 123 past users with diagnoses of stroke (CVA), multiple sclerosis (MS), incomplete spinal cord injury (SCI), traumatic brain injury (TBI) and cerebral palsy (CP). INTERVENTION: Functional electrical stimulation (FES) to correct dropped foot in subjects with an upper motor neuron lesion, using the ODFS. MAIN OUTCOME MEASURES: Purpose-designed questionnaire. RESULTS: Return rate 64% current users (mean duration of use 19.5 months) and 43% past users (mean duration of use 10.7 months). Principal reason cited for using equipment was a reduction in the effort of walking. Principal reasons identified for discontinuing were an improvement in mobility, electrode positioning difficulties and deteriorating mobility. There were some problems with reliability of equipment. Level of service provided was thought to be good. CONCLUSION: The ODFS was perceived by the users to be of considerable benefit. A comprehensive clinical follow-up service is essential to achieve the maximum continuing benefit from FES-based orthoses

Teng E.L., McNeal D.R., Kralj A., and Waters R.L. (1976) Electrical stimulation and feedback training: effects on the voluntary control of paretic muscles. Arch. Phys. Med. Rehabil. 57, 228-233.
Abstract: The carry-over effect of gait-synchronized stimulation of the peroneal nerve on voluntary dorsiflexion of the paretic foot was evaluated in hemiplegic patients. The influence of providing audiovisual feedback of performance on voluntary control was also evaluated. Each patient received three test sessions separated at least one week apart. In each session, measurement of isometric torque from voluntary effort was repeated four times: before, and at 0, 30 and 60 minutes after a 20- minute walk period. Session 2 involved both peroneal stimulation during walking and performance feedback during voluntary efforts. Session 1 had stimulation only. Session 3 had feedback only. The results were inconsistent among the patients. Where increase of voluntary dorsiflexion was obtained, it was more a consequence of performance feedback than peroneal stimulation. General problems of using isometric torque produced by voluntary dorsiflexion as a measure of the carry- over effect are discussed

Tong K.Y. and Granat M.H. (1999) Reliability of neural-network functional electrical stimulation gait- control system. Med. Biol. Eng Comput. 37, 633-638.
Abstract: Functional electrical stimulation (FES) has been used for restoring walking in spinal-cord injured (SCI) persons. Using artificial intelligence (AI), FES controllers have been developed that allow the automatic phasing of stimulation, to replace the function of hand or heel switches. However, there has been no study to evaluate the reliability of these AI systems. Neural networks were used to construct FES controllers to control the timing of stimulation. Different numbers of sensors in the sensor set and different numbers of data points from each sensor were used. Two incomplete-SCI subjects were recruited, and each was tested on three separate occasions. The results show the neural-network controllers can maintain a high accuracy (around 90% for the two- and three-sensor groups and 80% for the one-sensor group) over a period of six months. Two or three sensors were sufficient to provide enough information to construct a reliable FES control system, and the number of data points did not have any effect on the reliability of the system

Tong K.Y. and Granat M.H. (1999) Gait control system for functional electrical stimulation using neural networks. Med. Biol. Eng Comput. 37, 35-41.
Abstract: In functional electrical stimulation (FES) systems for restoring walking in spinal cord injured (SCI) individuals, hand switches are the preferred method for controlling stimulation timing. Through practice the user becomes an 'expert' in determining when stimulation should be applied. Neural networks have been used to 'clone' this expertise but these applications have used small numbers of sensors, and their structure has used a binary output, giving rise to possible controller oscillations. It was proposed that a three-layer structure neural network with continuous function, using a larger number of sensors, including 'virtual' sensors, can be used to 'clone' this expertise to produce good controllers. Using a sensor set of ten force sensors and another of 13 'virtual' kinematic sensors, a good FES control system was constructed using a three-layer neural network with five hidden nodes. The sensor set comprising three sensors showed the best performance. The accuracy of the optimum three-sensor set for the force sensors and the virtual kinematic sensors was 90% and 93%, respectively, compared with 81% and 77% for a heel switch. With 32 synchronised sensors, binary neural networks and continuous neural networks were constructed and compared. The networks using continuous function had significantly fewer oscillations. Continuous neural networks offer the ability to generate good FES controllers

Turbes C.C. (1997) Repair, reconstruction, regeneration and rehabilitation strategies to spinal cord injury. Biomed. Sci. Instrum. 34, 351-356.
Abstract: The structural changes seen in the transected spinal cord followed by transplantation of the distal ends (neuroma) of intercostal nerve inserted into the spinal cord proximal and distal to the transection lesion site. This activates CNS axonal regeneration. 2,3,4 These changes refer to the plasticity in the nervous system following damage to the spinal cord. There is regeneration and growth and synapotogenesis and remodeling of synaptic connections, development of reflex activity in the denervated cord. Nerve growth factors and neurotrophic factors sustain and maintain a degree of functional integrity of structural neural circuitry. 2,3,4,13 The end result is standing, stepping, and reflex walking in 28 female mature dogs. 2,3,4,5 Electrical stimulation of the anastomosed intercostal nerves resulted in hind limb movements and recording of the electromyograms of the contracting muscles. Twenty-six control dogs and animals with behavioral depression are unable to follow rehabilitative procedures developed muscle atrophy, ankylosis of joints, decrease in bone density, decrease in reflex activity of the spinal cord distal to the transection. 2,3,4,5

Turk R., Kralj A., Bajd T., Stefancic M., and Benko H. (1980) The alteration of paraplegic patients muscle properties due to electrical stimulation exercising. Paraplegia 18, 386-391.
Abstract: The influence of daily surface electrical stimulation of paraplegic patients' muscles is discussed in the paper. The optimisation of stimulation and training parameters and functionality of retrained muscles when performing erect standing or primitive walking, is discussed

Udo M., Matsukawa K., Kamei H., Minoda K., and Oda Y. (1981) Simple and complex spike activities of Purkinje cells during locomotion in the cerebellar vermal zones of decerebrate cats. Exp. Brain Res. 41, 292-300.
Abstract: In walking cats decerebrated at the premammillary level, single neurone activity of Purkinje cells (P-cells) with long corticofugal axons was recorded in the cerebellar vermis. The P-cells (N = 145) were identified as they showed spontaneous simple and complex spikes and also antidromic activation from Deiters' nucleus. These P-cells were classified into 6 groups according to the receptive fields of the climbing fibre responses (CFRs) which were evoked by electrical stimulation in each limb at the radial and sciatic nerve bundles. One group designated as forelimb units received the CFRs from both forelimbs and from neither hindlimb. According to previous studies, this group of P-cells is thought to make inhibitory connections with Deiters neurones projecting to the ipsilateral cervicothoracic spinal cord. For the forelimb units, two types of discharge patterns for simple spikes were found in relation to limb movements during locomotion. Type I cells showed one peak in their firing rate in the late swing (E1) or early stance (E2) phase of the ipsilateral forelimb. Type II cells showed two peaks and two valleys during one step cycle: one peak was in the E1 phase, the other in the late stance (E3) or early swing (F) phase; each of the two valleys followed the peak. Complex spikes of the forelimb units occurred more frequently in the E1 phase than during the other phases. The increased activity of simple and complex spikes of the forelimb units in the E2 phase is suggested to have a functional significance in preparing the appropriate floor reaction forces that appear upon touchdown on the ipsilateral forelimb

van der L.L., Boks L.M., van Wezel B.M., Goris R.J., and Duysens J.E. (2000) Leg muscle reflexes mediated by cutaneous A-beta fibres are normal during gait in reflex sympathetic dystrophy. Clin. Neurophysiol. 111, 677-685.
Abstract: OBJECTIVES: Reflex sympathetic dystrophy (RSD) is, from the onset, characterized by various neurological deficits such as an alteration of sensation and a decrease in muscle strength. We investigated if afferent A-beta fibre-mediated reflexes are changed in lower extremities affected by acute RSD.METHODS: The involvement of these fibres was determined by analyzing reflex responses from the tibialis anterior (TA) and biceps femoris (BF) muscles after electrical stimulation of the sural nerve. The reflexes were studied during walking on a treadmill to investigate whether the abnormalities in gait of the patients were related either to abnormal amplitudes or deficient phase-dependent modulation of reflexes. In 5 patients with acute RSD of the leg and 5 healthy volunteers these reflex responses were determined during the early and late swing phase of the step cycle.RESULTS: No significant difference was found between the RSD and the volunteers. During early swing the mean amplitude of the facilitatory P2 responses in BF and TA increased as a function of stimulus intensity (1.5, 2 and 2.5 times the perception threshold) in both groups. At end swing the same stimuli induced suppressive responses in TA. This phase-dependent reflex reversal from facilitation in early swing to suppression in late swing occurred equally in both groups. CONCLUSIONS: In the acute phase of RSD of the lower extremity there is no evidence for abnormal A-beta fibre-mediated reflexes or for defective regulation of such reflexes. This finding has implications for both the theory on RSD pathophysiology and RSD models, which are based on abnormal functioning of A-beta fibres

van Griethuysen C.M., Paul J.P., Andrews B.J., and Nicol A.C. (1982) Biomechanics of functional electrical stimulation. Prosthet. Orthot. Int. 6, 152-156.
Abstract: Patients with hemiplegia frequently have difficulty in walking due to lack of eversion and dorsiflexion capability of the foot. One method of treating these patients utilizes functional electrical stimulation (FES). The effect of FES on locomotion, co-ordination, proprioception and balance sense was assessed using instrumented gait analysis and a postural sway test. In general patients treated with FES showed either a marked improvement or very little change. Any improvement was reflected in postural sway and ankle control during locomotion. Changes in hip and knee control were insignificant

van Meeteren N.L., Brakkee J.H., Helders P.J., and Gispen W.H. (1998) The effect of exercise training on functional recovery after sciatic nerve crush in the rat. J. Peripher. Nerv. Syst. 3, 277-282.
Abstract: Two separate experiments were carried out in order to evaluate the influence of moderate swim training and treadmill running on the rate of recovery of sensorimotor function following sciatic nerve injury in the rat. Nerve injury was induced by sciatic nerve crush. In the first experiment, rats were subjected to swim exercise (180 m daily), either for 7 days before, or for 14 consecutive days after nerve injury. In the second experiment rats were exercised on a motor driven treadmill device (10 m/min for 30 min twice daily) for 21 days. The recovery from nerve injury was assessed by means of an analysis of the free walking pattern (motor function) and the foot withdrawal reflex (sensory function) by electrical stimulation. The swim training program before or after crush did not affect the recovery of locomotor or sensory function. Treadmill running significantly deteriorated the gradual return of motor function (p < 0.05), but did not influence sensory recovery. We conclude that swim training does not interfere with functional sensorimotor recovery after sciatic nerve injury, and that a mild program of treadmill running retards recovery. We hypothesize that the retardation of recovery as a result of treadmill running is the consequence of the stress inflicted by the negative reinforcement used in the treadmill, or due to the severity of the training. /O?>

van Wezel B.M., Ottenhoff F.A., and Duysens J. (1997) Dynamic control of location-specific information in tactile cutaneous reflexes from the foot during human walking. J. Neurosci. 17, 3804-3814.
Abstract: The purpose of the present study was to determine whether tactile cutaneous reflexes from the skin of the foot contain location-specific information during human walking. Muscular responses to non-nociceptive electrical stimulation of the sural, posterior tibial, and superficial peroneal nerves, each supplying a different skin area of the foot, were studied in both legs during walking on a treadmill. For all three nerves the major responses in all muscles were observed at a similar latency of approximately 80-85 msec. In the ipsilateral leg these reflex responses and their phase-dependent modulation were highly nerve- specific. During most of the stance phase, for example, the peroneal and tibial nerves generally evoked small responses in the biceps femoris muscle. In contrast, during late swing large facilitations generally occurred for the peroneal nerve, whereas suppressions were observed for the tibial nerve. In the contralateral leg the reflex responses for the three nerves were less distinct, although some nerve specificity was observed for individual subjects. It is concluded that non-nociceptive stimulation of the sural, posterior tibial, and superficial peroneal nerves each evokes distinct reflex responses, indicating the presence of location-specific information from the skin of the foot in cutaneous reflexes during human walking. It will be argued that differentially controlled reflex pathways can account for the differences in the phase-dependent reflex modulation patterns of the three nerves, which points to the dynamic control of this information during the course of a step cycle

Vanderwolf C.H. and Pappas B.A. (1980) Reserpine abolishes movement-correlated atropine-resistant neocortical low voltage fast activity. Brain Res. 202, 79-94.
Abstract: Following a large dose of atropine, rats display large amplitude slow waves in the neocortex during immobility, tremor, tooth-chattering and face-washing (Type II behavior) but display low voltage fast activity (LVFA) during walking, struggling, postural changes and head movement (Type I behavior). Rats treated with a large dose of reserpine usually continue to display LVFA during immobility as well as during movement although large amplitude slow waves are present more frequently than normal. A combination of reserpine and atropine abolishes all LVFA even during intense sensory stimulation or electrical stimulation of the reticular formation. Chlorpromazine, lysergic acid diethylamide, methysergide, phenoxybenzamine, pimozide, promethazine, propranolol and trifluoperazine do not have this effect when combined with atropine. In rats treated with nialamide prior to reserpine and atropine, LVFA continues to occur in association with Type I behavior just as in rats given atropine alone. It is proposed that the occurrence of LVFA in the neocortex is determined by two distinct reticulocortical systems. A cholinergic system produces all LVFA occurring during Type II behavior and a second system, dependent on a monoamine, produces LVFA in association with Type I behavior. The view that LVFA is a correlation of arousal or the sleep-waking cycle is criticized

Vanderwolf C.H., Harvey G.C., and Leung L.W. (1987) Transcallosal evoked potentials in relation to behavior in the rat: effects of atropine, p-chlorophenylalanine, reserpine, scopolamine and trifluoperazine. Behav. Brain Res. 25, 31-48.
Abstract: Single pulse electrical stimulation of the sensorimotor cortex in waking rats produced an evoked response in the contralateral sensorimotor cortex. The slow wave response consisted of: (1) an early component that was negative at the pial surface and in layer V, and was associated with multiunit discharge; and (2) a late component that was mainly negative at the surface, positive in layer V, and was associated with multiunit suppression. Previous research suggests that the early component represents summed excitatory postsynaptic potentials; the late component summed inhibitory postsynaptic potentials. Both components could be elicited by direct stimulation of the corpus callosum and both were abolished by midline callosal section. The amplitude and duration of the late component varied with concurrent motor activity in a striking manner. It was large during waking immobility and also during face-washing, licking the paws, chewing food and drinking water, but was much reduced or absent during head movements, walking and changes in posture. Only minor changes were associated with the transition from waking immobility to slow wave sleep. A series of pharmacological experiments indicated that the behavior-related variation in the late component of the transcallosal evoked response was dependent on both cholinergic and serotonergic transmission

Vodovnik L., Kralj A., Stanic U., Acimovic R., and Gros N. (1978) Recent applications of functional electrical stimulation to stroke patients in Ljubljana. Clin. Orthop. 64-70.
Abstract: Functional movements can be restored after stroke by portable neuroelectric stimulator controlled by the patient. This field of activity is called functional electrical stimulation (FES). A common example of FES is electric stimulation of the peroneal to prevent dropfoot. A more sophisticated multichannel enables stimulation of more than one paralyzed muscle of the leg. This system is used temporarily to facilitate recovery of muscle function following stroke. Upper extremity FES systems have proven more difficult to develop than lower extremity systems designed to improve walking. A single-channel hand stimulator is available to assist finger movements

Waters R.L., Garland D.E., Perry J. (1979) Stiff-legged gait in hemiplegia: Surgical correction. J Bone Joint Surg 61A, 927-933.

Waters R.L., Frazier J., Garland D., Jordan C., Perry J. (1982) Electroneuromyographic gait analysis before and after treatment for hemiplegic equinus and equinovarus deformity. J Bone Joint Surg 64A, 284-288.

Waters R.L., McNeal D.R., Faloon W., Clifford B. (1985) Functional electrical stimulation of the peroneal nerve for hemiplegia: long-term clinical follow-up. J Bone Joint Surg 67A, 792-793.

Waters R.L., Campbell J.M., and Nakai R. (1988) Therapeutic electrical stimulation of the lower limb by epimysial electrodes. Clin. Orthop. 44-52.
Abstract: The problem of inadequate hip stability prevents many patients with head trauma, stroke, or spinal injury from balancing on one limb in order to take a step. There is no adequate orthotic substitute for hip instability, and electrical stimulation with surface electrodes cannot effectively activate the deep hip muscles. This report describes a clinical program in which electrical stimulation via surgically placed electrodes is combined with routine tendon lengthening and transfers and physical therapy. The electrodes are fixed to the epimysium and the leads directed subcutaneously to exit the skin at a common site for attachment to a commercially available stimulator. Preliminary results indicate that functional muscle contractions of the deep hip muscles can be obtained with epimysial electrodes and that stimulation can be used to augment walking ability. The results demonstrate the safety and effectiveness of percutaneous electrical stimulation and contribute to the development of a practical, implanted stimulation system for patients who do not regain hip instability after an upper motor neuron lesion

Waters R.L., Botte M.J., Jordan C., Perry J., Pinzur M.S. (1990) SYMPOSIUM: Rehabilitation of Stroke Patients-The Role of the Orthopaedic Surgeon. Contemporary Orthopaedics 20, 311-348.

Wheeler G.D., Ashley E.A., Harber V., Laskin J.J., Olenik L.M., Sloley D., Burnham R., Steadward R.D., and Cumming D.C. (1996) Hormonal responses to graded-resistance, FES-assisted strength training in spinal cord-injured. Spinal Cord. 34, 264-267.
Abstract: Functional electrical stimulation (FES) assisted resistance training has been effective in increasing muscular strength and endurance in spinal cord injured men and women in preparation for FES-assisted cycle programs and for FES-assisted standing and walking. Increases in blood pressure and a concomitant bradycardia suggestive of autonomic dysreflexia have been reported during FES-assisted resistance training. Self-induced autonomic dysreflexia in athletes who use wheelchairs suppressed the normal exercise induced serum testosterone increase. We, therefore, examined the changes in hematocrit and circulating levels of testosterone, sex hormone binding globulin (SHBG), cortisol, prolactin, norepinephrine and epinephrine during FES assisted resistance exercise in five high spinal cord injured men (SCI) and comparable maximal exercise in five able bodied controls (AB). Mean serum testosterone levels significantly increased with FES-assisted resistance training in SCI and maximal resistance exercise in AB with no significant change in hematocrit or SHBG. Prolactin, cortisol and epinephrine levels were unchanged while norepinephrine levels were significantly increased in SCI and AB. These findings suggest that there is no concern over inadequate physiological androgen response to an exercise stimulus in SCI. The data do not support the previous findings that elevated levels of norepinephrine in autonomic dysreflexia suppress testosterone response to exercise

Wieler M., Stein R.B., Ladouceur M., Whittaker M., Smith A.W., Naaman S., Barbeau H., Bugaresti J., and Aimone E. (1999) Multicenter evaluation of electrical stimulation systems for walking. Arch. Phys. Med. Rehabil. 80, 495-500.
Abstract: OBJECTIVE: To test the long-term benefits of several noninvasive systems for functional electrical stimulation (FES) during walking. DESIGN: Forty subjects (average years since injury, 5.4) were studied in four centers for an average time of 1 year. Gait parameters were tested for all subjects with and without FES. Thus, subjects served as their own controls, since the specific effect of using FES could be separated from improvements resulting from other factors (e.g., training). SETTING: Subjects used the devices in the community, but were tested in a university or hospital setting. PATIENTS: Subjects with spinal cord injury (n = 31) were compared to subjects with cerebral damage (n = 9). MAIN OUTCOME MEASURES: Gait parameters (speed, cycle time, stride length). Acceptance was studied by means of a questionnaire. RESULTS: Some initial improvement in walking speed (average increase of >20%) occurred, and continuing gains were seen (average total improvement, 45%). The largest relative gains were seen in the slowest walkers (speeds of <0.3 m/sec). Acceptance of the FES systems was good and improved systems have been developed using feedback from the subjects. CONCLUSIONS: Based on the improvements in speed and the acceptance of these FES systems, a greatly increased role for FES in treating gait disorders is suggested

Wild J.M. (1999) Trigeminal disynaptic circuit mediating corneal afferent input to M. depressor palpebrae inferioris motoneurons in the pigeon (Columba livia). J. Comp Neurol. 403, 391-406.
Abstract: Corneal afferent projections to the trigeminal brainstem nuclear complex (TBNC) and associated structures, as determined by transganglionic transport of various tracers, were found to be predominantly concentrated in two distinct patches in the dorsolateral medulla at periobex levels. One was in the external cuneate nucleus, and the other was in the ventralmost part of the ophthalmic division of the TBNC. The projections of putative second-order neurons in these regions, as determined by injections of wheat germ agglutinin conjugated to horseradish peroxidase into the dorsolateral medulla, were found to include the dorsal trigeminal motor nucleus (Vd), which innervates the M. depressor palpebrae inferioris. Electrical stimulation of Vd, which elicited lower eyelid movements, was then used to guide injections of tracer into Vd, which retrogradely labeled clusters of neurons in the corneal afferent recipient regions of the dorsolateral medulla. The lower eyelid of pigeons, unlike the nictitating membrane and upper lid, does not appear to be appreciably involved in either reflex blinking in response to relatively mild stimulation of the cornea (e.g., air puff), or in eye closure during the saccade-like head movements associated with walking, or in eye closure during pecking; but in response to a stimulus that makes corneal contact, an upward movement of the lower lid follows descent of the nictitating membrane and upper lid as part of a defensive eye- closing mechanism. The anatomical results thus appear to define a dedicated disynaptic trigeminal sensorimotor circuit for the control of lower eyelid motility in response to mechanical or noxious stimuli of the cornea. Injections of tracers into the lower and upper eyelids labeled palpebral sensory afferents that terminated predominantly in maxillary and ophthalmic portions, respectively, of the dorsal horn of upper cervical spinal segments. These terminal fields were therefore largely separate from those of corneal afferents. There were no specific corneal afferent projections upon accessory abducens motoneurons that innervate the two muscles controlling the nictitating membrane

Winchester P., Carollo J.J., and Habasevich R. (1994) Physiologic costs of reciprocal gait in FES assisted walking. Paraplegia 32, 680-686.
Abstract: This study reports the velocity and physiologic cost index (PCI) of ambulation using a functional electrical stimulation (FES) system for ambulation in paraplegic spinal cord injured subjects. Using established techniques, average velocity and heart rate (HR) were measured on five subjects trained with the Parastep system. PCI was reported for the four subjects who achieved a steady state during ambulation with the Parastep system. It was found that walking performance varied greatly between subjects, and was correlated to frequency of use of the system. Velocity of walking with the Parastep system ranged from 4.6 to 24.3 m/min. In the four subjects where steady state was achieved, PCI ranged from 2.30 to 6.26 beats/m. The average walking speed and PCI were similar to the values reported using alternative mechanical or hybrid systems available to the spinal cord injured for restoration of upright locomotion

Wong A.M., Su T.Y., Tang F.T., Cheng P.T., and Liaw M.Y. (1999) Clinical trial of electrical acupuncture on hemiplegic stroke patients.  Am. J. Phys. Med. Rehabil. 78, 117-122.
Abstract: To assess the efficacy of electrical acupuncture in the rehabilitation of patients with hemiplegia in stroke, we randomized 128 patients within 2 wk of stroke onset to receive either comprehensive rehabilitation plus electrical acupuncture (n = 59) or comprehensive rehabilitation only (n = 59). Electrical acupuncture was administered by electrical stimulation of acupuncture points through adhesive surface electrodes five times per week. Neurological status (Brunnstrom's stage) and the Chinese version of the Functional Independence Measure were assessed before treatment and at discharge. Patients treated with electrical acupuncture had a shorter duration of hospital stay for rehabilitation and better neurological and functional outcomes than the control group had, with a significant difference in scores for self-care and locomotion (P = 0.02). This result did not postulate the previous study that acupuncture therapy for stroke patients should depend on needle manual and "de qi" response. We suggest that electrical acupuncture through adhesive surface electrodes in conjunction with current optimal rehabilitation programs is a convenient and effective therapy for stroke patients

Yamamoto K., Ohnishi A., Noda S., Umezaki H., and Yamamoto T. (1989) [An autopsy case of carcinomatous sensory neuropathy associated with gastric adenosquamous carcinoma]. Rinsho Shinkeigaku 29, 493-496.
Abstract: A 61-year-old man was admitted on May 1986 with complaints of hypesthesia and pain in the both legs, and of progressive difficulty in walking. Physical examination was unremarkable. On neurological examination, deep tendon reflexes were decreased in all extremities without pathological reflexes. Vibration sense was decreased severely at the medial malleolus and moderately at the anterior superior iliac spine. Joint sensation of the toes was moderately decreased. Light touch, temperature discrimination, and pinprick sensation were slightly decreased on fingers bilaterally and distal to the middle part of both legs. Muscle strength was normal. His gait was unsteady and Romberg's sign was positive. Finger to nose test and heel to knee test were mildly disturbed bilaterally. The sural nerve action potential was not elicited on electrical stimulation. Laboratory studies for malignancy showed gastric cancer. Only July 4, he underwent subtotal gastrectomy. Histologically it showed adenosquamous carcinoma. Postoperatively gait disturbance and pain in both legs improved slightly. Peak latencies of P2 of SEP following right and left posterior tibial nerve stimulation were 47. 9 msec and 48.8 msec on February 14, and 44.5 msec and 43.9 msec on October 6, 1986, respectively, and their postoperative shortening was evident. He died of multiple liver and lung metastasis of the gastric cancer in November 28, 1986. At autopsy, tumor metastasis were noted in liver, lung and perigastroduodenal and retroperitoneal lymph nodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Yang L., Granat M.H., Paul J.P., Condie D.N., and Rowley D.I. (1996) Further development of hybrid functional electrical stimulation orthoses. Spinal Cord. 34, 611-614.
Abstract: It is recognised that, in paraplegic walking with reciprocating gait orthoses, inadequate hip flexion angles may contribute to the low walking speed and high energy cost. In this study a new orthotic hip joint was developed which had a 2:1 flexion extension coupling ratio. Experiments on paraplegic subjects were conducted to evaluate this orthotic hip joint. It was found that the new hip joint was associated with a reduced energy cost and increased step length. A simple application of FES assisted hip flexion further increased walking speed and step length and reduced energy cost and crutch force impulse

Yang L., Condie D.N., Granat M.H., Paul J.P., and Rowley D.I. (1996) Effects of joint motion constraints on the gait of normal subjects and their implications on the further development of hybrid FES orthosis for paraplegic persons. J. Biomech. 29, 217-226.
Abstract: In this study the effects of angular motion constraints of the lower limbs on the gait of normal subjects were investigated. An assessment orthosis was developed with a new hip coupling mechanism which allows its ratio of reciprocal flexion to extension to be altered. The knee and ankle joints of the orthosis could also be set to be free or locked in specific directions of angular motion in the sagittal plane. A total of 12 different orthosis configurations was tested on three normal subjects. The kinematic, kinetic and electromyographic (EMG) data were collected using the VICON system, two Kistler forceplates, foot switches and an eight channel EMG system. The physiological cost index of walking was assessed by measuring the heart rate and walking speed. It was found that (1) a higher hip flexion-extension ratio was associated with lower energy cost and faster walking; (2) allowing the knee to flex significantly reduced the energy cost and increased the walking speed; (3) allowing the ankle to plantarflex during early stance phase reduced the knee flexing moment. The implications of these effects on the further development of hybrid functional electrical stimulation orthotic systems are discussed

Yang L., Granat M.H., Paul J.P., Condie D.N., and Rowley D.I. (1997) Further development of hybrid functional electrical stimulation orthoses. Artif. Organs 21, 183-187.
Abstract: In this study two aspects of hybrid functional electrical stimulation (FES) orthoses were investigated: joint motion constraints and FES control strategies. First, the effects of joint motion constraints on the gait of normal subjects were investigated using modern motion analysis systems, including electromyogram (EMG) and heart rate measurements. An orthosis was developed to impose joint motion constraints; the knee and ankle could be fixed or free, and the hip joint could rotate independently or coupled, according to a preset flexion-extension coupling ratio (FECR). Compared with a 1:1 hip FECR, a 2:1 hip FECR was associated with a reduced energy cost and increased speed and step length. The knee flexion during swing significantly reduced energy cost and increased walking speed. Ankle plantar flexion reduced the knee flexing moment during the early stance phase. Second, trials on 3 paraplegic subjects were conducted to implement some of these findings. It appeared that the 2:1 FECR encouraged hip flexion and made leg swing easier. A simple FES strategy increased walking speed and step length and reduced crutch force impulse using fixed orthotic joints

Yokoyama T., Sugiyama K., Nishizawa S., Yokota N., Ohta S., and Uemura K. (1999) Subthalamic nucleus stimulation for gait disturbance in Parkinson's disease. Neurosurgery 45, 41-47.
Abstract: OBJECTIVE: A preliminary study of subthalamic nucleus (STN) stimulation was performed to determine its applicability for the treatment of gait and postural disturbances in Parkinson's disease. METHODS: Five Parkinson's disease patients with freezing gait and postural instability were selected for this study. Their ages ranged from 60 to 73 years (mean+/-standard deviation, 65.6+/-4.8 years). Semi- microelectrode recording was used to identify the STN and to place a chronic electrical stimulation electrode within the right STN in all patients. The Unified Parkinson's Disease Rating Scale and the modified Hoehn and Yahr Staging Scale were used to assess patients in on- and off-drug conditions before surgery and 3 months after surgery. RESULTS: The scores on the Hoehn and Yahr Staging Scale and the total Unified Parkinson's Disease Rating Scale for akinesia (P < 0.05), gait (P < 0.05), and gait and posture (P < 0.01) in off-drug on-stimulation conditions significantly improved over the preoperative and postoperative off-drug off-stimulation conditions (analysis of variance [ANOVA], P < 0.01). Improvement over the preoperative scores was 24% on the Hoehn and Yahr Staging Scale, 43.6% on the total Unified Parkinson's Disease Rating Scale, 33.4% for akinesia, 36.6% for gait, and 38.7% for gait and posture. However, stimulation in the on-drug phase did not show a significant difference compared with pre- and postoperative conditions (ANOVA, P > 0.05). Comparisons between preoperative on-drug and postoperative off-drug on-stimulation conditions revealed that there were no significant differences in the scores, except for gait (ANOVA, P < 0.05). The scores on subscales for falling, freezing, walking, and gait in off-drug on-stimulation conditions were significantly improved over the scores for preoperative and postoperative off-stimulation (ANOVA, P < 0.05), but the score for postural stability remained unchanged. CONCLUSION: Our findings showed that STN stimulation effectively alleviates freezing gait and improves walking to its status during the preoperative on-drug phase and can be applied for treatment of Parkinson's disease patients with these symptoms

Zehr E.P., Fujita K., and Stein R.B. (1998) Reflexes from the superficial peroneal nerve during walking in stroke subjects. J. Neurophysiol. 79, 848-858.
Abstract: The function of ipsilateral cutaneous reflexes was studied with short trains of stimuli presented pseudorandomly to the superficial peroneal nerve (SP; innervates the top of the foot) during treadmill walking in neurologically intact (NI) subjects and subjects who had had a stroke. Ankle and knee joint angles together with electromyograms (EMG) of tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG), vastus lateralis (VL), and biceps femoris (BF) muscles were recorded. Net reflex EMG and kinematic responses to stimulation were quantified in each of the 16 parts of the step cycle and responses compared between the stroke and NI subjects. Stimulation strongly suppressed extensor muscles throughout stance in the stroke subjects. TA muscle showed a significant suppression during swing phase that was correlated with reduced ankle dorsiflexion in both stroke and NI subjects. BF reflexes were facilitatory during parts of swing and VL reflexes were suppressive throughout stance in the stroke subjects. There was a significant correlation between BF facilitation and knee flexion during swing, which was stronger in NI subjects. We conclude that only part of the stumble correction to foot dorsum electrical stimulation observed in NI subjects is maintained after stroke, and that new, suppressive responses are seen

Zehr E.P. and Chua R. (2000) Modulation of human cutaneous reflexes during rhythmic cyclical arm movement. Exp. Brain Res. 135, 241-250.
Abstract: The organization and pattern of cutaneous reflex modulation is unknown during rhythmic cyclical movements of the human upper limbs. On the assumption that these cyclic arm movements are central pattern generator (CPG) driven as has been suggested for leg movements such as walking, we hypothesized that cutaneous reflex amplitude would be independent of electromyographic (EMG) muscle activation level during rhythmic arm movement (phase-dependent modulation, as is often the case in the lower limb during locomotion). EMG was recorded from eight muscles crossing the human shoulder, elbow, and wrist joints while whole arm rhythmic cyclical movements were performed. Cutaneous reflexes were evoked with trains of electrical stimulation delivered at non-noxious intensities (approximately 2 x threshold for radiating paresthesia) to the superficial radial nerve innervating the lateral portion of the back of the hand. Phasic bursts of rhythmic muscle activity occurred throughout the movement cycle. Rhythmic EMG and kinematic patterns were similar to what has been seen in the human lower limb during locomotor activities such as cycling or walking: there were extensive periods of reciprocal activation of antagonist muscles. For most muscles, cutaneous reflexes were modulated with the movement cycle and were strongly correlated with the movement-related background EMG amplitude. It is concluded that cutaneous reflexes are primarily modulated by the background muscle activity during rhythmic human upper limb movements, with only some muscles showing phase- dependent modulation

Zizic T.M., Hoffman K.C., Holt P.A., Hungerford D.S., O'Dell J.R., Jacobs M.A., Lewis C.G., Deal C.L., Caldwell J.R., Cholewczynski J.G., and . (1995) The treatment of osteoarthritis of the knee with pulsed electrical stimulation. J. Rheumatol. 22, 1757-1761.
Abstract: OBJECTIVE. The safety and effectiveness of pulsed electrical stimulation was evaluated for the treatment of osteoarthritis (OA) of the knee. METHODS. A multicenter, double blind, randomized, placebo controlled trial that enrolled 78 patients with OA of the knee incorporated 3 primary efficacy variables of patients' pain, patients' function, and physician global evaluation of patients' condition, and 6 secondary variables that included duration of morning stiffness, range of motion, knee tenderness, joint swelling, joint circumference, and walking time. Measurements were recorded at baseline and during the 4 week treatment period. RESULTS. Patients treated with the active devices showed significantly greater improvement than the placebo group for all primary efficacy variables in comparisons of mean change from baseline to the end of treatment (p < 0.05). Improvement of > or = 50% from baseline was demonstrated in at least one primary efficacy variable in 50% of the active device group, in 2 variables in 32%, and in all 3 variables in 24%. In the placebo group improvement of > or = 50% occurred in 36% for one, 6% for 2, and 6% for 3 variables. Mean morning stiffness decreased 20 min in the active device group and increased 2 min in the placebo group (p < 0.05). No statistically significant differences were observed for tenderness, swelling, or walking time. CONCLUSION. The improvements in clinical measures for pain and function found in this study suggest that pulsed electrical stimulation is effective for treating OA of the knee. Studies for longterm effects are warranted

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