Transcutaneous functional electrical stimulation for grasping in subjects with cervical spinal cord injury

STUDY DESIGN: Case series. OBJECTIVES: To evaluate the benefit, shortcomings and acceptance of a new transcutaneous functional electrical stimulation (FES) technology aimed at improving the grasp function in tetraplegic subjects in acute and postacute rehabilitation. SETTING: Spinal cord injury (SCI) centre, university hospital. METHODS:: Subjects (N=11) with complete or incomplete SCI at C4/5-C7 who started FES 1-67 months after their accident were included. Hand function tests, analysis of video recordings and of written documentation of FES sessions, status of muscle strength, and follow-up query were used as outcome measures. RESULTS: Nine subjects used FES as a neuroprosthesis. Eight demonstrated improved grasp function and performance in activities of daily living. In one subject, no benefit from FES was observed. Two other subjects showed improvements in muscle strength and facilitation of active movement with FES. Four subjects successfully integrated FES as neuroprosthesis in everyday life within the rehabilitation centre. Three received the system for home use. The most relevant reasons for stopping the FES application were: (i) improvement of voluntary grasp function, (ii) physical and psychological problems, (iii) no available stimulator for home use, and (iv) insufficient assistance for electrode placement at home. Shortcomings related to the transcutaneous surface technology (eg pain or coactivation of neighbouring muscles) could usually be reduced, or did not limit the efficiency or acceptance of FES. Individually designed digital or analogue control devices were preferred. CONCLUSION: Tetraplegic subjects in acute and postacute rehabilitation can profit from a new transcutaneous FES system with respect to functional use and independence. It can be implemented in the rehabilitation programme for muscle strengthening and facilitation of voluntary activity. For a successful application of FES, there is a need for individual electrode placement, stimulation programmes, and FES control devices.     

Surface electrical stimulation of skeletal muscle after spinal cord injury.

STUDY DESIGN: Survey. OBJECTIVE: Examine muscle contractile activity during electrical stimulation (ES) after spinal cord injury (SCI). SETTING: General community of Athens, Georgia, USA. METHODS: Eight clinically complete SCI adults (C6 to T12) 4+/-1 (mean+/-SE) years post injury and eight able-bodied adults were studied. Surface ES was applied to the left m. quadriceps femoris for three sets of 10, 1 s isometric actions (50 Hz trains, 400 micros biphasic pulses, 50 micros phase delay, 1 s: 1 s duty cycle) with 90 s of rest between sets. Current was set to evoke isometric torque that was (1) sufficient to elicit knee extension with 2.3 kg attached to the ankle (low level ES), and (2) intended to equal 30% (mid level ES) or 60% of maximal voluntary torque of able-bodied adults (high level ES, able-bodied only). The absolute and relative cross-sectional area (CSA) of m. quadriceps femoris that was stimulated as reflected by contrast shift in magnetic resonance images and torque were measured. RESULTS: Six+/-2, 20+/-2 and 38+/-4% of the average CSA of m. quadriceps was stimulated during low, mid and high level ES, respectively, for able-bodied. Corresponding values for SCI for low and mid level ES were greater (61+/-12 and 92+/-7%, P = 0.0002). Torque was related to the CSA (cm2) of stimulated muscle (Nm = 3.53 x stimulated CSA+13, r2 = 0.68, P = 0.0010), thus ES of a greater per cent of m. quadriceps femoris in SCI was attributed to their smaller muscle (24+/-3 vs 73+/-5 cm2, P = 0.0001). The decline in torque ranged from 9+/-l to 15+/-4% within and over sets for low, mid or high level ES in able-bodied. SCI showed greater (P = 0.0001) fatigue (19+/-3 to 47+/-6%). CONCLUSION: The territory of muscle activation by surface electrical stimulation varies among SCI patients. Given sufficient current, a large portion of the muscle of interest can be stimulated. The resulting torque is modest, however, compared to that attainable in able-bodied individuals due to the small size and limited fatigue resistance of skeletal muscle years after spinal cord injury.     

Electromechanical gait training with functional electrical stimulation: case studies in spinal cord injury

STUDY DESIGN: Single case studies. OBJECTIVES: To describe the technique of intensive locomotor training on an electromechanical gait trainer (GT) combined with functional electrical stimulation (FES). SETTING: Neurological Rehabilitation Clinic, Berlin, Germany. METHODS: Four spinal cord-injured (SCI) patients, one tetraparetic, two paraparetic, and one patient with an incomplete cauda syndrome, more than 3 months postinjury, who were unable to walk at all, or with two therapists. They received 25 min of locomotor training on the GT plus FES daily for 5 weeks in addition to the regular therapy. RESULTS: The patients tolerated the programme well, and therapists rated the programme less strenuous compared to manually assisted treadmill training. Gait ability improved in all four patients; three patients could walk independently on the floor with the help of technical aids, and one required the help of one therapist after therapy; gait speed and endurance more than doubled, and the gastrocnemius activity increased in the patients with a central paresis. CONCLUSION: This combined technique allows intensive locomotor therapy in SCI subjects with reduced effort from the therapists. The patients' improved walking ability confirmed the potential of locomotor therapy in SCI subjects.     

Gait training regimen for incomplete spinal cord injury using functional electrical stimulation

STUDY DESIGN: Case series, and repeated assessments of the same individuals. OBJECTIVE: To demonstrate the feasibility and efficacy of a multiweek intervention on walking function in people with chronic, incomplete spinal cord injuries. SETTING: Rehabilitation hospital for spinal cord injury (SCI) in Toronto, Canada. METHODS: A convenience sample of five subjects with chronic, incomplete SCI trained for 12-18 weeks using a new multichannel neuroprosthesis for walking. The following outcome measures were recorded throughout the training period: walking speed, step frequency and average stride length based on a 2-min walk test. Also identified were which walking aids and orthoses subjects preferred to use, and whether they employed a step-to or step-through gait strategy. Follow-up measurements of three subjects were made up to 10 weeks after treatment. RESULTS: All subjects demonstrated significant improvements in walking function over the training period. Four of the subjects achieved significantly increased walking speeds, which were due to increases in both stride length and step frequency. The fifth subject experienced a significant reduction in preferred assistive devices. Follow-up measurements revealed that two subjects walked slightly slower several weeks after treatment, but they still walked significantly faster than at the start of treatment. CONCLUSION: The gait training regimen was effective for improving voluntary walking function in a population for whom significant functional changes are not expected. This application of functional electrical therapy is viable for rehabilitation of gait in incomplete SCI.     

Functional electrical stimulation after spinal cord injury.

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.     

A report of anticipated benefits of functional electrical stimulation after spinal cord injury

Background

Functional electrical stimulation (FES) has been regularly used to offset several negative body composition and metabolic adaptations following spinal cord injury (SCI). However, the outcomes of many FES trials appear to be controversial and incoherent.

Objective

To document the potential consequences of several factors (e.g. pain, spasms, stress and lack of dietary control) that may have attenuated the effects on body composition and metabolic profile despite participation in 21 weeks of FES training.

Participant

A 29-year-old man with T6 complete SCI participated in 21 weeks of FES, 4 days per week.

Methods

Prior to and following training, the participant performed arm-crank-graded exercise testing to measure peak VO₂. Tests conducted included anthropometrics and dual energy X-ray absorptiometry body composition assessments, resting energy expenditure, plasma lipid profiles and intravenous glucose tolerance tests.

Results

The participant frequently reported increasing pain, stress and poor eating habits. VO₂ peak decreased by 2.4 ml/kg/minute, body mass increased by 8.5 kg, and body mass index increased from 25 to 28 kg/m². Waist and abdominal circumferences increased by 2–4 cm, while %fat mass increased by 5.5%. Absolute increases in fat mass and fat-free mass of 8.4 and 1 kg, respectively, were reported. Fasting and peak plasma glucose increased by 12 and 14.5%, while lipid panel profiles were negatively impacted.

Conclusion

Failure to control for the listed negative emerging factors may obscure the expected body composition and metabolic profile adaptations anticipated from FES training.     

Lower extremity functional electrical stimulation cycling promotes physical and functional recovery in chronic spinal cord injury

Abstract

Objective

To examine the effect of long-term lower extremity functional electrical stimulation (FES) cycling on the physical integrity and functional recovery in people with chronic spinal cord injury (SCI).

Design

Retrospective cohort, mean follow-up 29.1 months, and cross-sectional evaluation.

Setting

Washington University Spinal Cord Injury Neurorehabilitation Center, referral center.

Participants

Twenty-five people with chronic SCI who received FES during cycling were matched by age, gender, injury level, and severity, and duration of injury to 20 people with SCI who received range of motion and stretching.

Intervention

Lower extremity FES during cycling as part of an activity-based restorative treatment regimen.

Main outcome measure

Change in neurological function: motor, sensory, and combined motor–sensory scores (CMSS) assessed by the American Spinal Injury Association Impairment scale. Response was defined as ≥1 point improvement.

Results

FES was associated with an 80% CMSS responder rate compared to 40% in controls. An average 9.6 CMSS point loss among controls was offset by an average 20-point gain among FES subjects. Quadriceps muscle mass was on average 36% higher and intra/inter-muscular fat 44% lower, in the FES group. Hamstring and quadriceps muscle strength was 30 and 35% greater, respectively, in the FES group. Quality of life and daily function measures were significantly higher in FES group.

Conclusion

FES during cycling in chronic SCI may provide substantial physical integrity benefits, including enhanced neurological and functional performance, increased muscle size and force-generation potential, reduced spasticity, and improved quality of life.     

Clinical applications of electrical stimulation after spinal cord injury

During the last one-half century, electrical stimulation has become clinically significant for improving health and restoring useful function after spinal cord injury. Short-term stimulation can be provided by electrodes on the skin or percutaneous fine wires, but implanted systems are preferable for long-term use. Electrical stimulation of intact lower motor neurons can exercise paralyzed muscles and reverse wasting; improve strength, endurance, and cardiovascular fitness; and may reduce the progression of osteoporosis. Other potential therapeutic uses being investigated include reduction of spasticity, prevention of deep vein thrombosis, and improvement of tissue health. Pacing of intact phrenic nerves in high tetraplegia can produce effective respiration without mechanical ventilation, allowing improved speech, increased mobility, and increased sense of well-being. Improvement of cough has also been demonstrated. Stimulation of intact sacral nerves can produce effective micturition and reduce urinary tract infection; it can also improve bowel function and erection. It is usually combined with posterior sacral rhizotomy to improve continence and bladder capacity, and the combination has been shown to reduce costs of care. Electroejaculation can now produce semen in most men with spinal cord injury. Significant achievements have also been made in restoring limb function. Useful hand grasp can be provided in C5 and C6 tetraplegia, reducing dependence on adapted equipment and assistants. Standing, assistance with transfers, and walking for short distances can be provided to selected persons with paraplegia, improving their access to objects, places, and opportunities that are inaccessible from a wheelchair. This review summarizes the current state of therapeutic and neuroprosthetic applications of electrical stimulation after spinal cord injury and identifies some future directions of research and clinical and commercial development.     

Perceptual threshold to cutaneous electrical stimulation in patients with spinal cord injury

STUDY DESIGN: Prospective experimental. OBJECTIVES: The aim of this study was to develop a quantitative sensory test (QST) that could be used for assessing the level and the density (degree of impairment) of spinal cord injury (SCI) and for monitoring neurological changes in patients with SCI. SETTING: National Spinal Injuries Centre, Stoke Mandeville Hospital, Buckinghamshire Hospitals NHS Trust, UK. METHODS: Perceptual threshold to 3 Hz cutaneous electrical stimulation was measured in 30 control subjects and in 45 patients with SCI at American Spinal Injuries Association (ASIA) sensory key points for selected dermatomes between C3 and S2 bilaterally. Electrical perceptual threshold (EPT) was recorded as the lowest ascending stimulus intensity out of three tests at which the subject reported sensation. The level of SCI according to EPT results was established for right and left sides as the most caudal spinal segment at which patient's EPT was within the control range (mean +/- 2 standard deviation (SD)). The level of SCI, according to EPT, was then compared with clinical sensory level derived according to ASIA classification. RESULTS: In the control group, EPT depended on the dermatome tested and was lowest for T1 (1.01 +/- 0.23 mA, mean +/- SD) and highest for L5 (3.32 +/- 1.14 mA). There was strong correlation between corresponding right and left dermatomes and between repeated assessments. In the SCI group, the level of lesion according to EPT and clinical testing was the same in 43 of the 90 tests (48%). In 37 cases (41%), the EPT level was higher than the clinical level, and in 10 cases (11%), it was lower. Below the level of lesion in incomplete SCI and in the zone of partial preservation in complete SCI, the EPT values in most dermatomes were raised compared with the control group. CONCLUSIONS: EPT is a simple, reproducible QST that can assess both the level and the density of SCI. It seems to add sensitivity and resolution to the standard clinical testing and could be a useful adjunct in longitudinal monitoring of patients with SCI for research purposes during natural recovery and therapeutic interventions. SPONSORSHIP: International Spinal Research Trust (ISRT), UK, Grant CLI001.     

Histochemical changes in muscle of individuals with spinal cord injury following functional electrical stimulated exercise training.

STUDY DESIGN: Longitudinal training. OBJECTIVES: To determine the effects of functional electrical stimulated (FES) leg cycle ergometer training on muscle histochemical characteristics in individuals with motor-complete spinal cord injury (SCI). SETTING: University of Alberta, Edmonton, Alberta, Canada. METHODS: Six individuals with motor-complete SCI (age 31-50 years; 3-25 years post-injury) trained using FES leg cycle ergometry for 30 min, 3 days per week for 8 weeks. Biopsies of the vastus lateralis muscle were obtained pre- and post-training and analyzed for fibre composition, fibre size and capillarization. RESULTS: The majority of muscle fibres were classified as type 2 pre- and post-training. Average fibre area increased 23% (P<0.05) and capillary number increased 39% (P<0.05) with training. As a result of these proportional increases, capillarization expressed relative to fibre area was unchanged with training. CONCLUSIONS: FES leg cycle ergometer training results in proportional increases in fibre area and capillary number in individuals with SCI.     

Changes in spasticity following functional electrical stimulation cycling in patients with spinal cord injury: A systematic review

Context: Spasticity is one of the most common secondary impairment after spinal cord injury (SCI). It can lead to an increase in the level of disability. The functional electrical stimulation cycling (FES-cycling) promotes recovery in patients with SCI. No systematic review has been published examining the influence of FES-cycling on the spasticity of lower extremities post-SCI.Objective: This review aimed to investigate the effects of the FES-cycling on the lower extremities spasticity in patients with SCI.Methods: PubMed, Scopus, PEDro, REHABDATA, Web of Science, and MEDLINE were searched until December 2019. The methodological quality was assessed using the Physiotherapy Evidence Database (PEDro) scale.Results: Ten studies were met the inclusion criteria. Two were randomized clinical trials, cohort study (n = 2), and pilot study (n=6). The scores on the PEDro scale ranged from one to nine, with a median score of three. The results showed evidence for the beneficial effects of FES-cycling on the spasticity of lower extremities in individuals with SCI.Conclusion: The FES-cycling intervention may reduce the lower extremities spasticity in patients with various injury levels of SCI. It is not a suitable intervention for medically unstable patients or with contraindication for lower extremities movement. Further randomized controlled trials with a large sample size strongly warranted to confirm our findings.     

Implanted functional electrical stimulation: an alternative for standing and walking in pediatric spinal cord injury

STUDY DESIGN: Post intervention, repeated measures design, comparing two interventions. SETTING: Orthopedic pediatric hospital specializing in spinal cord injury. METHODS: Nine subjects, ages 7-20 years, received an eight-channel implanted lower extremity functional electrical stimulation (FES) system for standing and walking. Electrodes were placed to stimulate hip and knee extension, and hip abduction and adduction. Standing and walking were achieved through constant stimulation to the implanted muscles, allowing a swing through gait pattern with an assistive device. After training with FES and long leg braces (LLB), subjects were tested in eight upright mobility activities, which were scored based upon completion time and level of independence. RESULTS: Seven subjects completed data collection. These subjects completed four activities faster (P<0.02) and five activities more independently (P<0.025) with FES as compared to LLB. Transitions between sitting and standing, which were scored in isolation for two mobility activities, were achieved faster and with more independence with FES. In addition, subjects reported preferring FES for the majority of activities. No activity required more time or more assistance to complete with FES as compared to LLB. CONCLUSION: The implanted FES system provided these subjects with enhanced functional abilities over traditional LLB and decreased the need for physical assistance by a caregiver, suggesting that it is a realistic alternative for upright mobility in a pediatric population with spinal cord injury.     

Functional electrical stimulation for augmented walking in adolescents with incomplete spinal cord injury

BACKGROUND/OBJECTIVE: This study evaluated the effects of functional electrical stimulation (FES) applied to the muscles acting on the pelvis, hip, and knee on muscle strength, energy cost of walking, maximum walking distance and speed, step length and cadence, and joint kinematics during gait in 3 ambulatory adolescents with incomplete spinal cord injury (SCI). METHODS: Percutaneous FES was used to strengthen weakened muscles and to augment walking. After training, participants walked as desired at home with FES for 1 year. Data were collected at baseline (preintervention), and with FES on and FES off immediately following the training period and with FES on and FES off at 3, 6, and 12 months posttraining. RESULTS: Voluntary strength improved in 12 out of 13 stimulated muscles. Decreased energy cost, increased maximum walking distance and speed, increased step length, and improved joint kinematics during gait were demonstrated with FES on and FES off. DISCUSSION: FES was able to achieve selective stimulation of key weakened muscles for augmented walking. The data suggest that FES had both direct and carryover effects.     

Functional electrical stimulation of bladder and bowel in spinal cord injury

The purpose of this collective review is to examine the use of functional electrical stimulation for incontinence. The Finetech-Brindley bladder system enhances voiding through stimulation via electrodes implanted around the ventral sacral roots. Detrusor hyperreflexia is eliminated through complete dorsal rhizotomy, which results in loss of reflex defecation and reflex erection/reflex lubrication. Consequently, a new system is being devised in which functional electrical stimulation for incontinence in spinal cord injury can be achieved without dorsal rhizotomy.     

Urinary bladder control by electrical stimulation: Review of electrical stimulation techniques in spinal cord injury

Evacuation of urine in paraplegics without the need for catheters would be possible when voiding could be induced by eliciting a bladder contraction. A challenging option to obtain detrusor contraction is electrical stimulation of the detrusor muscle or its motor nerves. This article reviews the 4 possible stimulation sites where stimulation would result in a detrusor contraction: the bladder wall, the pelvic nerves, the sacral roots, and the spinal cord. With respect to electrode application, sacral root stimulation is most attractive. However, in general, sacral root stimulation results in simultaneous activation of both the detrusor muscle and the urethral sphincter, leading to little or no voiding. Several methods are available to overcome the stimulation-induced detrusor-sphincter dyssynergia and allow urine evacuation. These methods, including poststimulus voiding, fatiguing of the sphincter, blocking pudendal nerve transmission, and selective stimulation techniques that allow selective detrusor activation by sacral root stimulation, are reviewed in this paper.     

A clinically meaningful training effect in walking speed using functional electrical stimulation for motor-incomplete spinal cord injury

Context/Objective: The study aimed to investigate the presence of a training effect for rehabilitation of walking function in motor-incomplete spinal cord injury (SCI) through daily use of functional electrical stimulation (FES).

Setting: A specialist FES outpatient centre.

Participants: Thirty-five participants (mean age 53, SD 15, range 18-80; mean years since diagnosis 9, range 5 months - 39 years) with drop foot and motor-incomplete SCI (T12 or higher, ASIA Impairment Scale C and D) able to ambulate 10 metres with the use of a walking stick or frame.

Interventions: FES of the peroneal nerve, glutei and hamstrings as clinically indicated over six months in the community.

Outcome Measures: The data was analysed for a training effect (difference between unassisted ten metre walking speed at baseline and after six months) and orthotic effects (difference between walking speed with and without FES) initially on day one and after six months. The data was further analysed for a minimum clinically important difference (MCID) (>0.06 m/s).

Results: A clinically meaningful, significant change was observed for initial orthotic effect (0.13m/s, CI: 0.04-0.17, P?=?0.013), total orthotic effect (0.11m/s, CI: 0.04-0.18, P?=?0.017) and training effect (0.09m/s, CI: 0.02-0.16, P?=?0.025).

Conclusion: The results suggest that daily independent use of FES may produce clinically meaningful changes in walking speed which are significant for motor-incomplete SCI. Further research exploring the mechanism for the presence of a training effect may be beneficial in targeting therapies for future rehabilitation.     

Lower extremity functional neuromuscular stimulation in cases of spinal cord injury

Functional neuromuscular stimulation (FNS) provides a mechanism for the activation of muscles paralyzed by injury to the spinal cord. Although this technique was first used to treat patients with spinal cord injury over 20 years ago, only recent advances in electronics and biomechanics have made it a promising aid for the rehabilitation of these patients. Thus far, restoration of palmar prehension and lateral prehension in quadriplegics and of standing and biped gait in paraplegics has been achieved under carefully controlled laboratory conditions. This article reviews the current status of FNS and its potential as a practical tool to aid spinal cord-injured patients. Neurosurgeons who care for these patients might be expected to be involved in the future use of FNS if implantable systems are developed and tested.