Muscle atrophy is prevented in patients with acute spinal cord injury using functional electrical stimulation

Joint contact forces during semi-recumbent seated cycling

Semi-recumbent cycling performed from a wheelchair is a popular rehabilitation exercise following spinal cord injury (SCI) and is often paired with functional electrical stimulation. However, biomechanical assessment of this cycling modality is lacking, even in unimpaired populations, hindering the development of personalised and safe rehabilitation programs for those with SCI. This study developed a computational pipeline to determine lower limb kinematics, kinetics, and joint contact forces (JCF) in 11 unimpaired participants during voluntary semi-recumbent cycling using a rehabilitation ergometer. Two cadences (40 and 60 revolutions per minute) and three crank powers (15 W, 30 W, and 45 W) were assessed. A rigid body model of a rehabilitation ergometer was combined with a calibrated electromyogram-informed neuromusculoskeletal model to determine JCF at the hip, knee, and ankle. Joint excursions remained consistent across all cadence and powers, but joint moments and JCF differed between 40 and 60 revolutions per minute, with peak JCF force significantly greater at 40 compared to 60 revolutions per minute for all crank powers. Poor correlations were found between mean crank power and peak JCF across all joints. This study provides foundation data and computational methods to enable further evaluation and optimisation of semi-recumbent cycling for application in rehabilitation after SCI and other neurological disorders.

Combining FES and Exoskeletons in a Hybrid Haptic System for Enhancing VR Experience

Robotic technology and functional electrical stimulation (FES) have emerged as highly effective rehabilitative techniques for individuals with neuromuscular diseases, showcasting their ability to restore motor functions. Within the proposed study, we developed and tested a new hybrid controller combining an upper-limb exoskeleton with FES to enhance haptic feedback when performing task-oriented and bimanual movement, like pick-and-place, in a virtual environment. We investigated the performance of the proposed approach on eight unimpaired participants providing haptic feedback either only by the exoskeleton or by the hybrid system. The hybrid control presents two different modalities, assistive and resistive, to modulate the perception of the load. FES intensity is calibrated to the subjects' biomechanical properties and it is adjusted in real-time according to the real-time motion of the upper limbs. Experimental results highlighted the ability of the hybrid control to improve kinematic performance: in both hybrid modalities subjects reduced the target matching error(values between 0.048±0.007 m and 0.06±0.006 m) without affecting the normal motion smoothness (SPARC values in the hybrid conditions range from -2.58±0.12 to -3.30±0.13). Moreover, the resistive approach resulted in greater metabolic consumption (1.04±0.03 W/kg), indicating a more realistic experience of lifting a virtual object through FES that increased the perceived weight. The innovation in our hybrid control relies on the modulation of muscular activation during manipulation tasks, which could be a promising approach in the clinical treatment of neuromuscular diseases.

Exercise prescription for persons with spinal cord injury: a review of physiological considerations and evidence-based guidelines

Persons with spinal cord injury (SCI) experience gains in fitness, physical and mental health from regular participation in exercise and physical activity. Due to changes in physiological function of the cardiovascular, nervous, and muscular systems, general population physical activity guidelines and traditional exercise prescription methods are not appropriate for the SCI population. Exercise guidelines specific to persons with SCI recommend progressive training beginning at 20 min of moderate to vigorous intensity aerobic exercise twice per week transitioning to 30 min three times per week, with strength training of the major muscle groups two times per week. These population-specific guidelines were designed considering the substantial barriers to physical activity for persons with SCI and can be used to frame an individual exercise prescription. Rating of perceived exertion (i.e., perceptually regulated exercise) is a practical way to indicate moderate to vigorous intensity exercise in community settings. Adapted exercise modes include arm cycle ergometry, hybrid arm-leg cycling, and recumbent elliptical equipment. Body weight-supported treadmill training and other rehabilitation modalities may improve some aspects of health and fitness for people with SCI if completed at sufficient intensity. Disability-specific community programs offer beneficial opportunities for persons with SCI to experience quality exercise opportunities but are not universally available.

FES-rowing: a well-tolerated and highly beneficial exercise for a patient with Brown-Sequard syndrome

CONTEXT

Brown-Séquard Syndrome (BSS) is a rare neurological condition associated with Spinal Cord Injury (SCI). Hemisection of the spinal cord causes paralysis of the homolateral side, and thermoalgesic dysfunction on the opposite side. Cardiopulmonary and metabolic alterations have been reported. For all these patients, regular physical activity is highly recommended and functional electrical stimulation (FES) may be a good option, especially for those with paraplegia. However, to our knowledge, the effects of FES have primarily been studied in those with complete SCI and data regarding application and effects in patients with incomplete lesions (with sensory feedback) is lacking. The present case report therefore evaluated the feasibility and effectiveness of a 3-month FES-rowing program in a patient with BSS.

METHODS

Knee extensor muscle strength and thickness, walking and rowing capacities as well as quality of life were evaluated before and after 3 months of FES-rowing (two sessions per week) in a 54 year old patient with BSS.

RESULTS

The individual had excellent tolerance and adherence to the training protocol. All measured parameters were greatly improved after 3 months: on average, + 30% rowing capacity, + 26% walking capacity, + 24.5% isometric strength, + 21.9% quadriceps muscle thickness, + 34.5% quality of life.

CONCLUSION

FES-rowing appears to be well tolerated and highly beneficial for a patient with incomplete SCI and could therefore be considered as an appealing exercise option for these patients.

Effectiveness of the "Evidence-Based Scientific Exercise Guidelines" in Increasing Cardiorespiratory Fitness, Cardiometabolic Health, and Muscle Strength in Acute Spinal Cord Injury Rehabilitation: A Systematic Review

Objective

To determine the effect of exercise and physical activity interventions that meet current guideline recommendations on cardiorespiratory fitness, cardiometabolic health, and muscle strength in adults in the acute stage (<1 year post onset) of spinal cord injury (SCI) rehabilitation.

Data Sources

Six electronic databases (PubMed, CINAHL, SPORTDiscus, Google Scholar, National Institute Clinical Excellence, World Health Organization) were searched (January 2016-March 2022) to extend a previously published review.

Study Selection

Included studies implemented exercise interventions in the acute stage of SCI rehabilitation participants which met the exercise guidelines and measured cardiorespiratory fitness, cardiometabolic health, and strength outcomes.

Data Extraction

Titles and abstracts were screened against eligibility criteria and duplicates removed using EndNote X8. Full texts were independently assessed and results presented in a Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart. Data extraction was completed on included studies by 2 reviewers (L.R. and V.B.) using a modified Cochrane Group form.

Data Synthesis

Data were synthesized, appraised using the Modified Downs & Black checklist and presented in narrative and tabular format. This review was registered on PROSPERO (Register ID:CRD42021249441). Of the 1255 studies, 4 were included, featuring 108 total participants <1-year post-SCI. Functional electrical stimulation cycle ergometry reduced muscle atrophy after 3 months training and increased lean body mass after 6 months. Resistance training increased muscle peak torque, perceived muscle strength and function. Aerobic exercise interventions did not increase cardiorespiratory fitness.

Conclusions

Interventions meeting the exercise guidelines did not increase cardiorespiratory fitness but were shown to improve cardiometabolic health and perceived muscle strength and function in adults in the acute stage of SCI rehabilitation. Further empirical research using standardized outcome measures are required to explore the effectiveness of aerobic exercise and strengthening interventions in acute stage of SCI rehabilitation to support the development of exercise guidelines.

A systematic literature review of ankle-foot orthosis and functional electrical stimulation foot-drop treatments for persons with multiple sclerosis

Foot-drop is one of the most diagnosed and physically limiting symptoms persons with multiple sclerosis (pwMS) experience. Clinicians prescribe ankle-foot orthosis (AFO) and functional electrical stimulation (FES) devices to help alleviate the effects of foot drop, but it is unclear how their clinical and functional gait improvements compare given the user's level of disability, type of multiple sclerosis, walking environment, or desired physical activity. The research questions explored were what is the current state of AFO and FES research for pwMS? What are the prevailing research trends? What definitive clinical and functional device comparisons exist for pwMS? eight databases were systematically searched for relevant literature published between 2009 and 2021. The American Association of Orthotists and Prosthetists and Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines for systematic literature reviews were followed. A team of 3 researchers critically evaluated 17 articles that passed eligibility criteria. This review discusses the current state and trends of research, provides evidence statements on device effects, and recommends improvements for future studies. A meta-analysis would be informative, but study variability across the literature makes directly comparing AFO and FES device effects unreliable. This review contributes new and useful information to multiple sclerosis literature that can be used by both clinicians and researchers. Clinicians can use the provided insights to prescribe more effective, customized treatments, and other researchers can use them to evaluate and design future studies.

The Role of Transcranial Magnetic Stimulation, Peripheral Electrotherapy, and Neurophysiology Tests for Managing Incomplete Spinal Cord Injury

Efforts to find therapeutic methods that support spinal cord functional regeneration continue to be desirable. Natural recovery is limited, so high hopes are being placed on neuromodulation methods which promote neuroplasticity, such as repetitive transcranial magnetic stimulation (rTMS) and electrical stimulation used as treatment options for managing incomplete spinal cord injury (iSCI) apart from kinesiotherapy. However, there is still no agreement on the methodology and algorithms for treatment with these methods. The search for effective therapy is also hampered by the use of different, often subjective in nature, evaluation methods and difficulties in assessing the actual results of the therapy versus the phenomenon of spontaneous spinal cord regeneration. In this study, an analysis was performed on the database of five trials, and the cumulative data are presented. Participants (iSCI patients) were divided into five groups on the basis of the treatment they had received: rTMS and kinesiotherapy (N = 36), peripheral electrotherapy and kinesiotherapy (N = 65), kinesiotherapy alone (N = 55), rTMS only (N = 34), and peripheral electrotherapy mainly (N = 53). We present changes in amplitudes and frequencies of the motor units’ action potentials recorded by surface electromyography (sEMG) from the tibialis anterior—the index muscle for the lower extremity and the percentage of improvement in sEMG results before and after the applied therapies. The increase in values in sEMG parameters represents the better ability of motor units to recruit and, thus, improvement of neural efferent transmission. Our results indicate that peripheral electrotherapy provides a higher percentage of neurophysiological improvement than rTMS; however, the use of any of these additional stimulation methods (rTMS or peripheral electrotherapy) provided better results than the use of kinesiotherapy alone. The best improvement of tibialis anterior motor units’ activity in iSCI patients provided the application of electrotherapy conjoined with kinesiotherapy and rTMS conjoined with kinesiotherapy. We also undertook a review of the current literature to identify and summarise available works which address the use of rTMS or peripheral electrotherapy as neuromodulation treatment options in patients after iSCI. Our goal is to encourage other clinicians to implement both types of stimulation into the neurorehabilitation program for subjects after iSCI and evaluate their effectiveness with neurophysiological tests such as sEMG so further results and algorithms can be compared across studies. Facilitating the motor rehabilitation process by combining two rehabilitation procedures together was confirmed.

Effectiveness of FES-supported leg exercise for promotion of paralysed lower limb muscle and bone health-a systematic review

Leg exercises through standing, cycling and walking with/without FES may be used to preserve lower limb muscle and bone health in persons with physical disability due to SCI. This study sought to examine the effectiveness of leg exercises on bone mineral density and muscle cross-sectional area based on their clinical efficacy in persons with SCI. Several literature databases were searched for potential eligible studies from the earliest return date to January 2022. The primary outcome targeted was the change in muscle mass/volume and bone mineral density as measured by CT, MRI and similar devices. Relevant studies indicated that persons with SCI that undertook FES- and frame-supported leg exercise exhibited better improvement in muscle and bone health preservation in comparison to those who were confined to frame-assisted leg exercise only. However, this observation is only valid for exercise initiated early (i.e., within 3 months after injury) and for ≥30 min/day for ≥ thrice a week and for up to 24 months or as long as desired and/or tolerable. Consequently, apart from the positive psychological effects on the users, leg exercise may reduce fracture rate and its effectiveness may be improved if augmented with FES.

Impact of rehabilitation on volumetric muscle loss in subjects with traumatic spinal cord injury: A systematic review

BACKGROUND

Spinal cord injury (SCI) leads to spinal nerve fiber tract damage resulting in functional impairments. Volumetric muscle loss (VML), a skeletal muscle volume abnormal reduction, is represented by atrophy below the injury level. The strategies for VML management included personalized approaches, and no definite indications are available.

OBJECTIVE

To identify the rehabilitation effects of VML in subjects with SCI (humans and animals).

METHODS

PubMed, Scopus, and Web of Science databases were systematically searched to identify longitudinal observational studies with individuals affected by traumatic SCI as participants; rehabilitation treatment as intervention; no control, sham treatment, and electrical stimulation programs as control; total lean body and lower limb lean mass, cross-sectional area, functional gait recovery, muscle thickness, and ultrasound intensity, as outcome.

RESULTS

Twenty-four longitudinal observational studies were included, evaluating different rehabilitation approaches' effects on the VML reduction in subjects affected by SCI. The data showed that electrical stimulation and treadmill training are effective in reducing the VML in this population.

CONCLUSION

This systematic review underlines the need to treat subjects with traumatic SCI (humans and animals) with different rehabilitation approaches to prevent VML in the subacute and chronic phases. Further clinical observations are needed to overcome the bias and to define the intervention's timing and modalities.

Effects of Kilohertz Frequency, Burst Duty Cycle, and Burst Duration on Evoked Torque, Perceived Discomfort and Muscle Fatigue: A Systematic Review

ABSTRACT

Kilohertz-frequency alternating current is used to minimize muscle atrophy and muscle weakness and improve muscle performance. However, no systematic reviews have evaluated the best Kilohertz-frequency alternating current parameters for this purpose. We investigated the effects of the carrier frequency, burst duty cycles, and burst durations on evoked torque, perceived discomfort, and muscle fatigue. A search of eight data sources by two independent reviewers resulted in 13 peer-reviewed studies being selected, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and rated using the PEDro scale to evaluate the methodological quality of the studies. Most studies showed that carrier frequencies up to 1 kHz evoked higher torque, while carrier frequencies between 2.5 and 5 kHz resulted in lower perceived discomfort. In addition, most studies showed that shorter burst duty cycles (10%-50%) induced higher evoked torque and lower perceived discomfort. Methodological quality scores ranged from 5 to 8 on the PEDro scale. We conclude that Kilohertz-frequency alternating current develops greater evoked torque for carrier frequencies between 1 and 2.5 kHz and burst duty cycles less than 50%. Lower perceived discomfort was generated using Kilohertz-frequency alternating currents between 2.5 and 5 kHz and burst duty cycles less than 50%.

Humans at the dawn of the in-body electrical nerve stimulation era

Background

The neuroprosthesis laparoscopic implantation technique for electric pelvic nerve stimulation was introduced to gynaecology over 15 years ago to treat intractable pelvic neuropathic pain. Following this first indication, other applications were developed, particularly in parapleology. The LION procedure developed to assist patients with paraplegia and common problems associated with inertia when confined to a wheelchair could find revolutionary applications in aging medicine and prevention.

Materials and Methods

Spinal cord injured patients who have undergone the Possover's LION procedure.

Main outcome measure

PubMed was systematically searched to identify peer-reviewed articles published in English that reported on LION procedure.

Results

Three independent studies published recently (100 patients worldwide) have shown revolutionary recovery of supra-spinal control in patients with chronic spinal cord injury following pelvic nerves stimulation, with 70% of them establishing a walker/crutches-assisted gait. The same studies have also shown significant whole-body muscle-mass building, peripheral vasodilatation, and an unexpected improvement in bone mineral density.

Conclusion

These ground-breaking findings could find revolutionary applications in aging medicine and the prevention of osteoporosis, with a huge impact on global public health. Humanity is on the cusp of an exciting new era following the introduction of the in-body electrical nerve stimulation technique.

What is new?

In-body electrical nerve stimulation for recovery and/or control of human peripheral somatic and autonomic nervous systems.

Twelve-Week Daily Gluteal and Hamstring Electrical Stimulation Improves Vascular Structure and Function, Limb Volume, and Sitting Pressure in Spinal Cord Injury: A Pilot Feasibility Study

OBJECTIVE

We examined the long-term effects of low-intensity electrical stimulation on (micro)vasculature and sitting pressure of a home-based, wearable electrical stimulation device in a pilot feasibility study.

DESIGN

In a cohort observation before-after trial, nine middle-aged male (n = 8) and female (n = 1) individuals (48 ± 15 yrs) with American Spinal Injury Association A-C classified chronic (1-24 yrs) spinal cord injury underwent 12 wks of self-administered daily, low-intensity gluteal and hamstring electrical stimulation (50 Hz, 6 hrs [30-min electrical stimulation, 15-min rest]). Common femoral artery diameter and blood blow were determined with ultrasound, skin vascular function during local heating was assessed using Laser-Doppler flowmetry, thigh volume was estimated using leg circumferences and skinfolds, and interface sitting pressure was measured using pressure mapping.

RESULTS

Resting common femoral artery diameter increased (0.73 ± 0.20 to 0.79 ± 0.22 cm, P < 0.001) and baseline common femoral artery blood flow increased (0.28 ± 0.12 to 0.40 ± 0.15 l/min, P < 0.002). Gluteal cutaneous vascular conductance showed a time*temperature interaction (P = 0.01) with higher conductance at 42°C after 12 wks. Ischial peak pressure decreased (P = 0.003) by 32 ± 23 mm Hg and pressure gradient decreased (23 ± 7 to 16 ± 6 mm Hg, P = 0.007). Thigh volume increased (+19%, P = 0.01).

CONCLUSIONS

Twelve-week daily home-based gluteal and hamstring electrical stimulation is feasible and effective to improve (micro)vasculature and sitting pressure, and electrical stimulation may have clinical implications for ameliorating pressure ulcers and (micro)vascular complications in spinal cord injury.

Motorless cadence control of standard and low duty cycle-patterned neural stimulation intensity extends muscle-driven cycling output after paralysis

Background

Stimulation-driven exercise is often limited by rapid fatigue of the activated muscles. Selective neural stimulation patterns that decrease activated fiber overlap and/or duty cycle improve cycling exercise duration and intensity. However, unequal outputs from independently activated fiber populations may cause large discrepancies in power production and crank angle velocity among pedal revolutions. Enforcing a constant cadence through feedback control of stimulus levels may address this issue and further improve endurance by targeting a submaximal but higher than steady-state exercise intensity.

Methods

Seven participants with paralysis cycled using standard cadence-controlled stimulation (S-Cont). Four of those participants also cycled with a low duty cycle (carousel) cadence-controlled stimulation scheme (C-Cont). S-Cont and C-Cont patterns were compared with conventional maximal stimulation (S-Max). Outcome measures include total work (W), end power (P_end), power fluctuation (PFI), charge accumulation (Q) and efficiency (η). Physiological measurements of muscle oxygenation (SmO₂) and heart rate were also collected with select participants.

Results

At least one cadence-controlled stimulation pattern (S-Cont or C-Cont) improved P_end over S-Max in all participants and increased W in three participants. Both controlled patterns increased Q and η and reduced PFI compared with S-Max and prior open-loop studies. S-Cont stimulation also delayed declines in SmO2 and increased heart rate in one participant compared with S-Max.

Conclusions

Cadence-controlled selective stimulation improves cycling endurance and increases efficiency over conventional stimulation by incorporating fiber groups only as needed to maintain a desired exercise intensity. Closed-loop carousel stimulation also successfully reduces power fluctuations relative to previous open-loop efforts, which will enable neuroprosthesis recipients to better take advantage of duty cycle reducing patterns.

Secreted Protein Acidic and Rich in Cysteine as an Exercise-Induced Gene: Towards Novel Molecular Therapies for Immobilization-Related Muscle Atrophy in Elderly Patients

Long periods of immobilization, among other etiologies, would result is muscle atrophy. Exercise is the best approach to reverse this atrophy. However, the limited or the non-ability to perform the required physical activity for such patients and the limited pharmacological options make developing novel therapeutic approaches a necessity. Within this context, secreted protein acidic and rich in cysteine (SPARC) has been characterized as an exercise-induced gene. Whereas the knock-out of this gene leads to a phenotype that mimics number of the ageing-induced and sarcopenia-related changes including muscle atrophy, overexpressing SPARC in mice or adding it to muscular cell culture produces similar effects as exercise including enhanced muscle mass, strength and metabolism. Therefore, this piece of writing aims to provide evidence supporting the potential use of SPARC/SPARC as a molecular therapy for muscle atrophy in the context of immobilization especially for elderly patients.

Handcycling with concurrent lower body low-frequency electromyostimulation significantly increases acute oxygen uptake: implications for rehabilitation and prevention

Background

Acute increases in exercise-induced oxygen uptake (V̇O₂) is crucial for aerobic training adaptations and depends on how much muscle mass is involved during exercising. Thus, handcycling is per se limited for higher maximal oxygen uptakes (V̇O₂max) due to restricted muscle involvement. Handcycling with additional and simultaneous application of low-frequency electromyostimulation (EMS) to the lower extremities might be a promising stimulus to improve aerobic capacity in disabled and rehabilitative populations.

Method

Twenty-six healthy young adults (13 female, age: 23.4 ± 4.5 years, height: 1.77 ± 0.09 m, mass: 71.7 ± 16.7 kg) completed 4 ×10 minutes of sitting (SIT), sitting with concurrent EMS (EMS_SIT), handcycling (60 rpm, 1/2 bodyweight as resistance in watts) (HANDCYCLE) and handcycling with concurrent EMS of the lower extremities (EMS_HANDCYCLE). During EMS_SIT and EMS_HANDCYCLE, low frequency EMS (impulse frequency: 4Hz, impulse width: 350 µs, continuous stimulation) was applied to gluteal, quadriceps and calf muscles. The stimulation intensity was selected so that the perceived pain could be sustained for a duration of 10 minutes (gluteus: 80.0 ± 22.7 mA, quadriceps: 94.5 ± 20.5 mA, calves: 77.5 ± 19.1 mA).

Results

Significant mode-dependent changes of V̇O₂ were found (p < 0.001, η _p ² = 0.852). Subsequent post-hoc testing indicated significant difference between SIT vs. EMS_SIT (4.70 ± 0.75 vs. 10.61 ± 4.28 ml min^-1 kg^-1, p < 0.001), EMS_SIT vs. HANDCYCLE (10.61 ± 4.28 vs. 13.52 ± 1.40 ml min^-1 kg^-1, p = 0.005), and between HANDCYCLE vs. EMS_HANDCYCLE (13.52 ± 1.40 vs. 18.98 ± 4.89 ml min^-1 kg^-1, p = 0.001).

Conclusion

Handcycling with simultaneous lower body low-frequency EMS application elicits notably higher oxygen uptake during rest and moderately loaded handcycling and may serve as an additional cardiocirculatory training stimuli for improvements in aerobic capacity in wheelchair and rehabilitation settings.

Activity-based therapy for individuals with spinal cord injury/disease: perspectives of acute care therapists

Study design

An exploratory descriptive study was conducted.

Objective

To determine if and how occupational therapists (OTs) and physical therapists (PTs) in acute care hospital settings use activity-based therapy (ABT) and its associated technologies.

Setting

Acute care hospital settings in Canada.

Methods

Semi-structured interviews were conducted with physical and occupational therapists, licensed in Canada, who worked in an acute care neurological setting with individuals with spinal cord injury or disease (SCI/D). To analyze the data, interpretive description was used. NVivo 12 was used for data management.

Results

Five physical therapists and two occupational therapists were interviewed (n = 7). Two therapists declined after reading a description of the study. Through analysis, the following themes were identified as affecting the delivery of ABT as part of SCI/D rehabilitation in the acute care setting: (1) Impact of patient acuity on ABT participation, (2) ABT approach unique to the acute care setting, and (3) Influence of acute care work environment and therapy practice. Throughout these themes, therapists referred to dosage as a limiting factor affecting ABT delivery.

Conclusions

Our research reveals that implementing ABT in an acute care setting is challenging considering the high dosage of movement practice required for ABT. To increase dosage and the use of ABT in acute care, strategies could include early patient education on ABT, strategic use of social supports, and use of portable technology already incorporated in acute care.

The Effect and Dose-Response of Functional Electrical Stimulation Cycling Training on Spasticity in Individuals With Spinal Cord Injury: A Systematic Review With Meta-Analysis

Background: To investigate the effect and dose-response of functional electrical stimulation cycling (FES-cycling) training on spasticity in the individuals with spinal cord injury (SCI). Method: Five electronic databases [PubMed, Scopus, Medline (Proquest), Embase, and Cochrane Central Register of Controlled Trials (CENTRAL)] were searched before September 2021. The human trials and studies of English language were only included. Two authors independently reviewed and extracted the searched studies. The primary outcome measure was spasticity assessed by Modified Ashworth Scale or Ashworth Scale for lower limbs. The secondary outcome measures were walking abilities, such as 6 Min Walk Test (6MWT), Timed Up and Go (TUG), and lower limbs muscle strength (LEMS). A subgroup analysis was performed to investigate the efficacious threshold number of training sessions. A meta-regression analysis was used to examine the linear relationship between the training sessions and the effect on spasticity. Results: A total of 764 studies were identified. After screening, 12 selected studies were used for the qualitative synthesis, in which eight of them were quantitatively analyzed. Eight studies included ninety-nine subjects in total with SCI (male: female = 83:16). The time since injury was from less than 4 weeks to 17 years. The age ranged from 20 to 67 years. American Spinal Injury Association (ASIA) impairment level of the number of participants was 59 for ASIA A, 11 for ASIA B, 18 for ASIA C, and 11 for ASIA D. There were 43 subjects with tetraplegia and 56 subjects with paraplegia. Spasticity decreased significantly (95% CI = - 1.538 to - 0.182, p = 0.013) in favor of FES-cycling training. The walking ability and LEMS also improved significantly in favor of FES-cycling training. The subgroup analysis showed that spasticity decreased significantly only in more than 20 training sessions (95% CI = - 1.749 to - 0.149, p = 0.020). The meta-regression analysis showed training sessions and spasticity were not significantly associated (coefficient = - 0.0025, SE = 0.0129, p = 0.849, R ² analog = 0.37). Conclusion: Functional electrical stimulation-cycling training can improve spasticity, walking ability, and the strength of the lower limbs in the individuals with SCI. The number of training sessions is not linearly related to the decrease of spasticity. Twenty sessions of FES-cycling training are required to obtain the efficacy to decrease spasticity.

Selective Myostatin Inhibition Spares Sublesional Muscle Mass and Myopenia-Related Dysfunction after Severe Spinal Cord Contusion in Mice

Clinically relevant myopenia accompanies spinal cord injury (SCI), and compromises function, metabolism, body composition, and health. Myostatin, a transforming growth factor (TGF)β family member, is a key negative regulator of skeletal muscle mass. We investigated inhibition of myostatin signaling using systemic delivery of a highly selective monoclonal antibody - muSRK-015P (40 mg/kg) - that blocks release of active growth factor from the latent form of myostatin. Adult female mice (C57BL/6) were subjected to a severe SCI (65 kdyn) at T9 and were then immediately and 1 week later administered test articles: muSRK-015P (40 mg/kg) or control (vehicle or IgG). A sham control group (laminectomy only) was included. At euthanasia, (2 weeks post-SCI) muSRK-015P preserved whole body lean mass and sublesional gastrocnemius and soleus mass. muSRK-015P-treated mice with SCI also had significantly attenuated myofiber atrophy, lipid infiltration, and loss of slow-oxidative phenotype in soleus muscle. These outcomes were accompanied by significantly improved sublesional motor function and muscle force production at 1 and 2 weeks post-SCI. At 2 weeks post-SCI, lean mass was significantly decreased in SCI-IgG mice, but was not different in SCI-muSRK-015P mice than in sham controls. Total energy expenditure (kCal/day) at 2 weeks post-SCI was lower in SCI-immunoglobulin (Ig)G mice, but not different in SCI-muSRK-015P mice than in sham controls. We conclude that in a randomized, blinded, and controlled study in mice, myostatin inhibition using muSRK-015P had broad effects on physical, metabolic, and functional outcomes when compared with IgG control treated SCI animals. These findings may identify a useful, targeted therapeutic strategy for treating post-SCI myopenia and related sequelae in humans.

Effects of functional electrical stimulation on muscle health after spinal cord injury

Spinal cord injury is a devastating condition interrupting voluntary movement and motor control. In response to unloading, skeletal muscle undergoes numerous adaptations, including rapid and profound atrophy, intramuscular fat accumulation, impaired muscular glucose metabolism and decreased force generation and muscle performance. Functional electrical stimulation (FES) involves electrically stimulating affected muscles to contract in a coordinated manner to create a functional movement or task. Effects of FES-cycling, rowing and resistance training on muscle health are described here. Briefly, FES-cycling and resistance training may slow muscle atrophy or facilitate muscle hypertrophy, and all modalities benefit muscle composition and performance to some extent. These interventions show promise as future rehabilitative tools after spinal cord injury.

Does aerobic exercise benefit persons with tetraplegia from spinal cord injury? A systematic review

CONTEXT

This review synthesizes the findings of previous research studies on the cardiovascular and metabolic benefits of aerobic exercise for individuals with tetraplegia secondary to spinal cord injury. They are often less active due to muscular paralysis, sensory loss, and sympathetic nervous system dysfunction that result from injury. Consequently, these persons are at higher risk for exercise intolerance and secondary health conditions.

OBJECTIVE

To evaluate the evidence concerning efficacy of aerobic exercise training for improving health and exercise performance in persons with tetraplegia from cervical injury.

METHODS

The search engines PubMed and Google Scholar were used to locate published research. The final 75 papers were selected on the basis of inclusion criteria. The studies were then rank-ordered using Physiotherapy Evidence Database.

RESULTS

Studies combining individuals with tetraplegia and paraplegia show that voluntary arm-crank training can increase mean peak power output by 33%. Functional electrical stimulation leg cycling was shown to induce higher peak cardiac output and stroke volume than arm-crank exercise. A range of peak oxygen uptake (VO_2peak) values have been reported (0.57-1.32 L/min). Both VO_2peak and cardiac output may be enhanced via increased muscle pump in the legs and venous return to the heart. Hybrid exercise (arm-crank and functional electrical stimulation leg cycling) can result in greater peak oxygen uptake and cardiovascular responses.

CONCLUSION

Evidence gathered from this systematic review of literature is inconclusive due to the lack of research focusing on those with tetraplegia. Higher power studies (level 1-3) are needed with the focus on those with tetraplegia.

Selective neural stimulation methods improve cycling exercise performance after spinal cord injury: a case series

BACKGROUND

Exercise after paralysis can help prevent secondary health complications, but achieving adequate exercise volumes and intensities is difficult with loss of motor control. Existing electrical stimulation-driven cycling systems involve the paralyzed musculature but result in rapid force decline and muscle fatigue, limiting their effectiveness. This study explores the effects of selective stimulation patterns delivered through multi-contact nerve cuff electrodes on functional exercise output, with the goal of increasing work performed and power maintained within each bout of exercise.

METHODS

Three people with spinal cord injury and implanted stimulation systems performed cycling trials using conventional (S-Max), low overlap (S-Low), low duty cycle (C-Max), and/or combined low overlap and low duty cycle (C-Low) stimulation patterns. Outcome measures include total work (W), end power (Pend), power fluctuation indices (PFI), charge accumulation (Q), and efficiency (η). Mann-Whitney tests were used for statistical comparisons of W and Pend between a selective pattern and S-Max. Welch's ANOVAs were used to evaluate differences in PFIs among all patterns tested within a participant (n ≥ 90 per stimulation condition).

RESULTS

At least one selective pattern significantly (p < 0.05) increased W and Pend over S-Max in each participant. All selective patterns also reduced Q and increased η compared with S-Max for all participants. C-Max significantly (p < 0.01) increased PFI, indicating a decrease in ride smoothness with low duty cycle patterns.

CONCLUSIONS

Selective stimulation patterns can increase work performed and power sustained by paralyzed muscles prior to fatigue with increased stimulation efficiency. While still effective, low duty cycle patterns can cause inconsistent power outputs each pedal stroke, but this can be managed by utilizing optimized stimulation levels. Increasing work and sustained power each exercise session has the potential to ultimately improve the physiological benefits of stimulation-driven exercise.

Timing and dosage of FES cycling early after acute spinal cord injury: A case series report

OBJECTIVE

To understand the progression in parameters of functional electrical stimulation (FES) cycling dosage (including duration, velocity, stimulation amplitudes, power output), and the resulting changes in muscle mass early after acute spinal cord injury (SCI).

METHODS

Three participants, 24-38 years old, with neurological injury level C4-T4, severity AIS (American Spinal Injury Association Impairment Scale) A-C, started FES cycling 16-20 days post injury while admitted at a level-1 trauma center in Canada, and continued for 8-13 weeks in a rehabilitation hospital. They performed three sessions/week of 15-45 min FES cycling, supine or sitting. FES parameters, cycling performance, and muscle cross-sectional area (CSA) in thighs and calves were measured every 2 weeks.

RESULTS

Progression in power output, but not in session duration, was limited in two participants who experienced stimulation-associated referred pain or apprehension, requiring limitation of stimulation amplitudes for up to 65 days after the start of FES cycling. Participants started with 15 min cycling at 20 RPM with no resistance (0 W), and progressed to 30-45 min at 30 RPM producing 8.8-19.0 W average power/session after 2-3 months. Initially, muscle CSA decreased in all 3 participants (up to 16% after 6 weeks), and recovered later after a variable period of FES cycling (up to 16% at 13.3 weeks).

CONCLUSION

Progression of FES cycling in the first 3 months after injury required a highly individualized approach, guided by participant response, rather than standardized increments in stimulation intensity or duration. Changes in muscle CSA did not always correspond with the dose of FES cycling.

Functional electrical stimulation cycling exercise after spinal cord injury: a systematic review of health and fitness-related outcomes

OBJECTIVES

The objective of this review was to summarize and appraise evidence on functional electrical stimulation (FES) cycling exercise after spinal cord injury (SCI), in order to inform the development of evidence-based clinical practice guidelines.

METHODS

PubMed, the Cochrane Central Register of Controlled Trials, EMBASE, SPORTDiscus, and CINAHL were searched up to April 2021 to identify FES cycling exercise intervention studies including adults with SCI. In order to capture the widest array of evidence available, any outcome measure employed in such studies was considered eligible. Two independent reviewers conducted study eligibility screening, data extraction, and quality appraisal using Cochranes' Risk of Bias or Downs and Black tools. Each study was designated as a Level 1, 2, 3 or 4 study, dependent on study design and quality appraisal scores. The certainty of the evidence for each outcome was assessed using GRADE ratings ('High', 'Moderate', 'Low', or 'Very low').

RESULTS

Ninety-two studies met the eligibility criteria, comprising 999 adults with SCI representing all age, sex, time since injury, lesion level and lesion completeness strata. For muscle health (e.g., muscle mass, fiber type composition), significant improvements were found in 3 out of 4 Level 1-2 studies, and 27 out of 32 Level 3-4 studies (GRADE rating: 'High'). Although lacking Level 1-2 studies, significant improvements were also found in nearly all of 35 Level 3-4 studies on power output and aerobic fitness (e.g., peak power and oxygen uptake during an FES cycling test) (GRADE ratings: 'Low').

CONCLUSION

Current evidence indicates that FES cycling exercise improves lower-body muscle health of adults with SCI, and may increase power output and aerobic fitness. The evidence summarized and appraised in this review can inform the development of the first international, evidence-based clinical practice guidelines for the use of FES cycling exercise in clinical and community settings of adults with SCI. Registration review protocol: CRD42018108940 (PROSPERO).

Effect of cycling and functional electrical stimulation with linear and interval patterns of timing on gait parameters in patients after stroke: a randomized clinical trial

OBJECTIVE

Patients in the chronic phase after a stroke are an underrepresented group in the literature. Therefore, the aim of this study was to compare the effects of cycling and functional electrical stimulation with linear versus interval patterns of timing on gait parameters in patients after stroke.

DESIGN

A double blinded, parallel, randomized clinical trial.

SETTING

Neuroscience Institute.

PARTICIPANTS

Patients with lower limb disability due to stroke (N = 30) with a stroke onset >6 months and <18 months.

INTERVENTIONS

Twenty-eight minutes of leg cycling with functional electrical stimulation with linear or interval patterns of timing applied to the peroneal and biceps femoris muscles, 3 times/week for 4 weeks.

MAIN MEASURES

Timed 10-Meter Walk Test and Functional Ambulation Classification were the primary outcome measures. The Modified Modified Ashworth scale, active range of motion, Timed Up and Go Test, and Single Leg Stance Test were the secondary outcome measures. Evaluation was performed at baseline, after 4, and after 8 weeks.

RESULTS

Thirty participants completed the 4-week intervention (interval group, n = 16; linear group, n = 14). The Functional Ambulation Classification, Timed 10-Meter Walk Test, and the Timed Up and Go Test improved significantly in both groups. The Modified Modified Ashworth scale scores for quadriceps and plantar flexion statistically decreased after 4-weeks in the interval group. Significant group-by-time interaction was shown for Timed Up and Go Test (p = 0.003, np²=0.228), knee flexion active range of motion (p < 0.001, np²=0.256) and dorsiflexion active range of motion (p < 0.001, np²=0.359). Modified Modified Ashworth scale and active range of motion in both the ankle and knee improved significantly in the interval group.

CONCLUSIONS

The functional electrical stimulation with cycling protocols improved the Functional Ambulation Classification, Timed 10-Meter Walk Test, active range of motion, Timed Up and Go Test, and Modified Modified Ashworth scale. An interval protocol of timing was more effective than the linear protocol in terms of spasticity and active range of motion.Implications for rehabilitationCycling + functional electrical stimulation training with an interval pattern of timing seems superior to cycling + functional electrical stimulation training with a linear pattern.Interval protocol has positive effects on spasticity and range of motion after 12 sessions in patients post stroke.Cycling + functional electrical stimulation improves functional mobility and speed in stroke survivors and the effects of this intervention lasted in follow-up assessment after one month.

Insights on the Potential Mechanisms of Action of Functional Electrical Stimulation Therapy in Combination With Task-Specific Training: A Scoping Review

OBJECTIVES

This scoping review was undertaken to synthetize and appraise the literature on the potential mechanisms of action of functional electrical stimulation therapy in combination with task-specific training (FEST + TST) in the rehabilitation following stroke, spinal cord injury, traumatic brain injury, or multiple sclerosis.

MATERIALS AND METHODS

The literature search was performed using multiple databases (including APA, PsycInfo, Medline, PubMed, EMBASE, CCRCT, and Cochrane Database of Systematic Reviews) from 1946 to June 2020. The literature search used the following terms: (spinal cord injury, paraplegia, tetraplegia, quadriplegia, stroke, multiple sclerosis, traumatic brain injury, or acquired brain injury) AND (functional electrical stimulation or FES). The search included clinical and preclinical studies without limits to language.

RESULTS

Of the 8209 titles retrieved from the primary search, 57 publications fulfilled the inclusion and exclusion criteria for this scoping review. While most publications were clinical studies (n = 50), there were only seven preclinical studies using animal models. The results of this review suggest that FEST + TST can result in multiple effects on different elements from the muscle to the cerebral cortex. However, most studies were focused on the muscle changes after FEST + TST.

CONCLUSIONS

The results of this scoping review suggest that FEST + TST can result in multiple effects on different elements of the neuromuscular system, while most research studies were focused on the muscle changes after FEST + TST. Despite the efficacy of the FEST + TST in the neurorehabilitation after CNS injury or disease, the results of this review underline an important knowledge gap with regards to the actual mechanism of action of FEST + TST.

The Pathophysiology of Osteoporosis after Spinal Cord Injury

Spinal cord injury (SCI) affects approximately 300,000 people in the United States. Most individuals who sustain severe SCI also develop subsequent osteoporosis. However, beyond immobilization-related lack of long bone loading, multiple mechanisms of SCI-related bone density loss are incompletely understood. Recent findings suggest neuronal impairment and disability may lead to an upregulation of receptor activator of nuclear factor-κB ligand (RANKL), which promotes bone resorption. Disruption of Wnt signaling and dysregulation of RANKL may also contribute to the pathogenesis of SCI-related osteoporosis. Estrogenic effects may protect bones from resorption by decreasing the upregulation of RANKL. This review will discuss the current proposed physiological and cellular mechanisms explaining osteoporosis associated with SCI. In addition, we will discuss emerging pharmacological and physiological treatment strategies, including the promising effects of estrogen on cellular protection.

Electrical stimulation of hindlimb skeletal muscle has beneficial effects on sublesional bone in a rat model of spinal cord injury

Spinal cord injury (SCI) results in marked atrophy of sublesional skeletal muscle and substantial loss of bone. In this study, the effects of prolonged electrical stimulation (ES) and/or testosterone enanthate (TE) on muscle mass and bone formation in a rat model of SCI were tested. Compared to sham-transected animals, a significant reduction of the mass of soleus, plantaris and extensor digitorum longus (EDL) muscles was observed in animals 6 weeks post-SCI. Notably, ES or ES + TE resulted in the increased mass of the EDL muscles. ES or ES + TE significantly decreased mRNA levels of muscle atrophy markers (e.g., MAFbx and MurF1) in the EDL. Significant decreases in bone mineral density (BMD) (-27%) and trabecular bone volume (-49.3%) at the distal femur were observed in animals 6 weeks post injury. TE, ES and ES + TE treatment significantly increased BMD by +6.4%, +5.4%, +8.5% and bone volume by +22.2%, and +56.2% and+ 60.2%, respectively. Notably, ES alone or ES + TE resulted in almost complete restoration of cortical stiffness estimated by finite element analysis in SCI animals. Osteoblastogenesis was evaluated by colony-forming unit-fibroblastic (CFU-F) staining using bone marrow mesenchymal stem cells obtained from the femur. SCI decreased the CFU-F+ cells by -56.8% compared to sham animals. TE or ES + TE treatment after SCI increased osteoblastogenesis by +74.6% and +67.2%, respectively. An osteoclastogenesis assay revealed significantly increased TRAP+ multinucleated cells (+34.8%) in SCI animals compared to sham animals. TE, ES and TE + ES treatment following SCI markedly decreased TRAP+ cells by -51.3%, -40.3% and -46.9%, respectively. Each intervention greatly reduced the ratio of RANKL to OPG mRNA of sublesional long bone. Collectively, our findings demonstrate that after neurologically complete paralysis, dynamic muscle resistance exercise by ES reduced muscle atrophy, downregulated genes involved in muscle wasting, and restored mechanical loading to sublesional bone to a degree that allowed for the preservation of bone by inhibition of bone resorption and/or by facilitating bone formation.

Pathophysiology, Biomarkers, and Therapeutic Modalities Associated with Skeletal Muscle Loss Following Spinal Cord Injury

A spinal cord injury (SCI) may lead to loss of strength, sensation, locomotion and other body functions distal to the lesion site. Individuals with SCI also develop secondary conditions due to the lack of skeletal muscle activity. As SCI case numbers increase, recent studies have attempted to determine the best options to salvage affected musculature before it is lost. These approaches include pharmacotherapeutic options, immunosuppressants, physical activity or a combination thereof. Associated biomarkers are increasingly used to determine if these treatments aid in the protection and reconstruction of affected musculature.

Functional Electrical Stimulation Therapy for Retraining Reaching and Grasping After Spinal Cord Injury and Stroke

Neurological conditions like hemiplegia following stroke or tetraplegia following spinal cord injury, result in a massive compromise in motor function. Each of the two conditions can leave individuals dependent on caregivers for the rest of their lives. Once medically stable, rehabilitation is the main stay of treatment. This article will address rehabilitation of upper extremity function. It is long known that moving the affected limb is crucial to recovery following any kind of injury. Overtime, it has also been established that just moving the affected extremities does not suffice, and that the movements have to involve patient’s participation, be as close to physiologic movements as possible, and should ideally stimulate the entire neuromuscular circuitry involved in producing the desired movement. For over four decades now, functional electrical stimulation (FES) is being used to either replace or retrain function. The FES therapy discussed in this article has been used to retrain upper extremity function for over 15 years. Published data of pilot studies and randomized control trials show that FES therapy produces significant changes in arm and hand function. There are specific principles of the FES therapy as applied in our studies: (i) stimulation is applied using surface stimulation electrodes, (ii) there is minimum to virtually no pain during application, (iii) each session lasts no more than 45–60 min, (iv) the technology is quite robust and can make up for specificity to a certain extent, and (v) fine motor function like two finger precision grip can be trained (i.e., thumb and index finger tip to tip pinch). The FES therapy protocols can be successfully applied to individuals with paralysis resulting from stroke or spinal cord injury.

Transcutaneous carbon dioxide application inhibits muscle atrophy after fracture in rats

BACKGROUND

Muscle atrophy causes difficulty in resuming daily activities after a fracture. Because transcutaneous carbon dioxide (CO₂) application has previously upregulated oxygen pressure in the local tissue, thereby demonstrating its potential in preventing muscle atrophy, here we investigated effects of CO₂ application on muscle atrophy after femoral shaft fracture.

METHODS

Thirty fracture model rats were produced and randomly divided into a no treatment (control group) and treatment (CO₂ group) groups. After treatment, the soleus muscle was dissected at post-fracture days 0, 14, and 21. Evaluations were performed by measuring muscle weight and performing histological examination and gene expression analysis.

RESULTS

Muscle weight was significantly higher in the CO₂ group than in the control group. Histological analysis revealed that the muscle fiber cross-sectional area was reduced in both groups. Nevertheless, the extent of atrophy was lesser in the CO₂ group. Muscle fibers in the control group tended to change into fast muscle fibers. Vascular staining revealed that more capillary vessels surrounded the muscle fibers in the CO₂ group than in the control group. Messenger RNA (mRNA) analysis revealed that the CO₂ group had a significantly enhanced expression of genes that were related to muscle synthesis.

CONCLUSION

Transcutaneous CO₂ application may be a novel therapeutic strategy for preventing skeletal muscle atrophy after fracture.

Feasibility of overnight electrical stimulation-induced muscle activation in people with a spinal cord injury. A Pilot study

Study Design

We investigated whether overnight ES is a feasible method to activate gluteal, quadriceps, and hamstrings muscles in a two-week experiment. Electrical stimulation (ES) induced muscle contractions have proven positive effects on risk factors for developing pressure ulcers in people with a spinal cord injury (SCI). Therefore prolonged overnight ES-induced muscle activation is interesting, but has never been studied.

Objective

To study feasibility of ES-induced leg muscle activation. In eight participants with motor complete SCI gluteal, hamstrings and quadriceps muscles were activated with a 2-weeks overnight stimulation protocol, 8 h per night, using specially developed ES-shorts.

Setting

The Netherlands.

Methods

Muscle fatigue was determined with a muscle contraction sensor. Questionnaires on sleep quality (SQ) and the ES-shorts usability were taken.

Results

After 8 h of activation muscles still contracted, although fatigue occurred, and mean contraction size was lower at the end of a cycle (p = 0.03). SQ (0-100) after intervention was 75, and 66 after 4 weeks without overnight ES (p = 0.04) indicating ES improves sleep quality. The usability of the ES-shorts was good.

Conclusions

This study shows that overnight ES-induced muscle activation using ES-shorts in SCI is a new, feasible method that does not interfere with sleep. The nightly use of the ES-shorts might be considered as an important part of the daily routine in SCI.

Neuromusculoskeletal Modeling-Based Prostheses for Recovery After Spinal Cord Injury

Concurrent stimulation and reinforcement of motor and sensory pathways has been proposed as an effective approach to restoring function after developmental or acquired neurotrauma. This can be achieved by applying multimodal rehabilitation regimens, such as thought-controlled exoskeletons or epidural electrical stimulation to recover motor pattern generation in individuals with spinal cord injury (SCI). However, the human neuromusculoskeletal (NMS) system has often been oversimplified in designing rehabilitative and assistive devices. As a result, the neuromechanics of the muscles is seldom considered when modeling the relationship between electrical stimulation, mechanical assistance from exoskeletons, and final joint movement. A powerful way to enhance current neurorehabilitation is to develop the next generation prostheses incorporating personalized NMS models of patients. This strategy will enable an individual voluntary interfacing with multiple electromechanical rehabilitation devices targeting key afferent and efferent systems for functional improvement. This narrative review discusses how real-time NMS models can be integrated with finite element (FE) of musculoskeletal tissues and interface multiple assistive and robotic devices with individuals with SCI to promote neural restoration. In particular, the utility of NMS models for optimizing muscle stimulation patterns, tracking functional improvement, monitoring safety, and providing augmented feedback during exercise-based rehabilitation are discussed.

End-user and clinician perspectives on the viability of wearable functional electrical stimulation garments after stroke and spinal cord injury

PURPOSE

Functional electrical stimulation (FES), through repetitive training (FES-therapy) or continuous assistance (neuro-prosthesis), can restore motor function after paralysis due to spinal cord injury or stroke. With current technology, patients are often incapable of independently applying FES, thereby limiting its use. Novel FES-garments with embedded stimulation electrodes were developed in collaboration with Myant, Canada, to address this problem. The purpose of this study was to collect the views of future end-users to inform the refinement of the device design and to obtain insights on subsequent commercialization of this rehabilitation and assistive technology.

METHODS

A qualitative study was undertaken to determine the needs of potential users (patients and clinicians; n = 19). Participant took part in interviews or focus groups after a presentation of the garments. An inductive content analysis was used to generate the themes from the data and identify data saturation.

RESULTS

The identified themes and sub-themes were: (1) User Perspectives: users' characteristics (needs, limitations), expected benefits (beliefs), and anticipated problems (fears); (2) Device Design: technical features, usability, and disadvantages of the garment, cables, stimulator, software, and interface; (3) Acquisition Process: organizational procedures (acquisition and adoption steps); and (4) Business Model: financial and strategic aspects to facilitate commercialization and support users.

CONCLUSIONS

The insights obtained from end-users and clinicians provide guidelines to optimize the development of novel FES-garments, and strategies for bringing the device to the market. The themes identified can serve to inform other rehabilitation and assistive technology developers with processes and ideas on how to meet these groups' needs.IMPLICATIONS FOR REHABILITATIONParticipants with neurological paralysis have interest and critical views on new rehabilitation and assistive technology, and the repercussions of using new technologies to address their function, health and wellbeing.The FES-garment design presented appeared acceptable to the end-users, pending resolution of certain shortcomings (wiring, operating duration, robustness, easiness to don and doff).End-users and clinicians had specific views regarding the acquisition process of new technologies (training, customization, and follow-up/support), which are important to take into consideration to ensure broad stakeholders uptake.

Garments for functional electrical stimulation: Design and proofs of concept

Introduction

Repeated use of functional electrical stimulation can promote functional recovery in individuals with neurological paralysis. We designed garments able to deliver functional electrical stimulation.

Methods

Shirts and pants containing electrodes knitted with a conductive yarn were produced. Electrodes were moistened with water before use. Stimulation intensity at four thresholds levels (sensory, movement, full range of motion, and maximal), stimulation comfort, and electrical properties of the interface were tested in one able-bodied subject with garment electrodes and size-matched conventional gel electrodes. The pants and shirt were then used to explore usability and design limitations.

Results

Compared to gel electrodes, fabric electrodes had a lower sensory threshold (on forearm muscles) but they had a higher maximal stimulation threshold (for all tested muscles). The stimulation delivery was comfortable when the garment electrodes were recently moistened; however, as the electrodes dried (within 9 to 18 min) stimulation became unpleasant. Inconsistent water content in the fabric electrodes caused inconsistent intensity thresholds and inconsistent voltage necessary to apply a desired stimulation current. Garments’ tightness and impracticality of electrode lead necessitate further design improvement.

Conclusions

Fabric electrodes offer a promising alternative to gel electrodes. Further work involving people with paralysis is required to overcome the identified challenges.

FES Cycling in Stroke: Novel Closed-Loop Algorithm Accommodates Differences in Functional Impairments

OBJECTIVE

The objective of this paper was to develop and test a novel control algorithm that enables stroke survivors to pedal a cycle in a desired cadence range despite varying levels of functional abilities after stroke.

METHODS

A novel algorithm was developed which automatically adjusts 1) the intensity of functional electrical stimulation (FES) delivered to the leg muscles, and 2) the current delivered to an electric motor. The algorithm automatically switches between assistive, uncontrolled, and resistive modes to accommodate for differences in functional impairment, based on the mismatch between the desired and actual cadence. Lyapunov-based methods were used to theoretically prove that the rider's cadence converges to the desired cadence range. To demonstrate the controller's real-world performance, nine chronic stroke survivors performed two cycling trials: 1) volitional effort only and 2) volitional effort accompanied by the control algorithm assisting and resisting pedaling as needed.

RESULTS

With a desired cadence range of 50-55 r/min, the developed controller resulted in an average rms cadence error of 1.90 r/min, compared to 6.16 r/min during volitional-only trials.

CONCLUSION

Using FES and an electric motor with a two-sided cadence control objective to assist and resist volitional efforts enabled stroke patients with varying strength and abilities to pedal within a desired cadence range.

SIGNIFICANCE

A protocol design that constrains volitional movements with assistance and resistance from FES and a motor shows potential for FES cycles and other rehabilitation robots during stroke rehabilitation.

The Effect of Electrically Induced Cycling and Nutritional Counseling on Cardiometabolic Health in Upper and Lower Motor Neuron Chronic Spinal Cord Injury: Dual Case Report

Introduction:

Various therapies have been utilized to improve cardiometabolic health after spinal cord injury (SCI), including Functional Electrical Stimulation (FES) cycling. Typically, FES is used in SCI cases resulting from Upper Motor Neuron Injury (UMN-SCI). However, it has been reported that FES may improve muscle torque and functional mobility in individuals with Lower Motor Neuron Injuries (LMN-SCI) but potential effects on cardiometabolic health have not been studied before. Thus, this study examined the cardiometabolic health response to FES cycling combined with nutritional counseling in two individuals with chronic SCI; one person with LMN-SCI and one with UMN-SCI.

Case Presentation:

Body composition, vascular stiffness, and glucose deposition were assessed before and after participation in the FES cycling and nutritional counseling program. Despite the decrease in body mass in the case of LMN-SCI but not UMN-SCI, the fat mass-to-lean mass ratio in the lower limbs and trunk increased +4% and +8% respectively, in the former and decreased −10% and −8% respectively in the latter. Both subjects decreased markers of central vascular stiffness (AIx@75, reflection magnitude) as well as blood glucose and HbA1c levels, however, the changes were greater in the case of UMN-SCI.

Discussion:

This dual case study provides only a partial support for the use of FES cycling alone or in combination with nutritional counseling for improving cardio metabolic health in LMN-SCI, however modest decreases in glucose and vascular stiffness warrant further investigations.

Spasticity and preservation of skeletal muscle mass in people with spinal cord injury

STUDY DESIGN

Cross-sectional OBJECTIVE: To investigate the association between skeletal muscle mass and spasticity in people with spinal cord injury (SCI).

SETTING

Tertiary level hospital in Seoul, Korea METHODS: Spasticity was evaluated in 69 participants with SCI using the spasticity sum score (SSS), Penn Spasm Frequency Scale (PSFS), and Spinal Cord Assessment Tool for Spastic Reflexes (SCATS). Skeletal muscle mass was measured using a dual-energy X-ray absorptiometry scanner, and skeletal muscle index was calculated by dividing skeletal muscle mass by height squared. Laboratory parameters including hemoglobin, albumin, creatinine, fasting glucose, and cholesterol were measured. Spearman's correlation analysis was performed to assess the association between the skeletal muscle mass and spasticity scales. Multiple linear regression analysis was used to present the independent association between them.

RESULTS

The participants' mean age was 41.8 years; 54 (78.3%) were male, and 46 (66.7%) were tetraplegic. Skeletal muscle index of lower extremities was significantly correlated with all spasticity scales. Spearman's correlation coefficients were 0.468, 0.467, 0.555, 0.506, and 0.474 for SSS, PSFS, SCATS clonus, SCATS flexor, and SCATS extensor with p-values < 0.001, respectively. After adjustment for age, sex, level of injury, body mass index, and serum creatinine, all spasticity scales were significantly associated with skeletal muscle index of lower extremities in multiple regression analysis. Standardized coefficients were 0.228, 0.274, 0.294, 0.210, and 0.227 for SSS, PSFS, SCATS clonus, SCATS flexor, and SCATS extensor.

CONCLUSIONS

Spasticity was significantly correlated with the skeletal muscle mass even after adjusting for possible confounders. Spasticity may need to be considered as an influencing factor in interventions such as electrical stimulation to preserve skeletal muscle mass.

Neuromodulation in the restoration of function after spinal cord injury

Neuromodulation, the use of electrical interfaces to alter neuronal activity, has been successful as a treatment approach in several neurological disorders, including deep brain stimulation for Parkinson's disease and epidural spinal stimulation for chronic pain. Neuromodulation can also be beneficial for spinal cord injury, from assisting basic functions such as respiratory pacing and bladder control, through to restoring volitional movements and skilled hand function. Approaches range from electrical stimulation of peripheral muscles, either directly or via brain-controlled bypass devices, to stimulation of the spinal cord and brain. Limitations to widespread clinical application include durability of neuromodulation devices, affordability and accessibility of some approaches, and poor understanding of the underlying mechanisms. Efforts to overcome these challenges through advances in technology, together with pragmatic knowledge gained from clinical trials and basic research, could lead to personalised neuromodulatory interventions to meet the specific needs of individuals with spinal cord injury.

Effects of ursolic acid on sub-lesional muscle pathology in a contusion model of spinal cord injury

Spinal Cord Injury (SCI) results in severe sub-lesional muscle atrophy and fiber type transformation from slow oxidative to fast glycolytic, both contributing to functional deficits and maladaptive metabolic profiles. Therapeutic countermeasures have had limited success and muscle-related pathology remains a clinical priority. mTOR signaling is known to play a critical role in skeletal muscle growth and metabolism, and signal integration of anabolic and catabolic pathways. Recent studies show that the natural compound ursolic acid (UA) enhances mTOR signaling intermediates, independently inhibiting atrophy and inducing hypertrophy. Here, we examine the effects of UA treatment on sub-lesional muscle mTOR signaling, catabolic genes, and functional deficits following severe SCI in mice. We observe that UA treatment significantly attenuates SCI induced decreases in activated forms of mTOR, and signaling intermediates PI3K, AKT, and S6K, and the upregulation of catabolic genes including FOXO1, MAFbx, MURF-1, and PSMD11. In addition, UA treatment improves SCI induced deficits in body and sub-lesional muscle mass, as well as functional outcomes related to muscle function, motor coordination, and strength. These findings provide evidence that UA treatment may be a potential therapeutic strategy to improve muscle-specific pathological consequences of SCI.

Evaluation of high-density, multi-contact nerve cuffs for activation of grasp muscles in monkeys

OBJECTIVE

The objective of this work was to evaluate whether nerve cuffs can selectively activate hand muscles for functional electrical stimulation (FES). FES typically involves identifying and implanting electrodes in many individual muscles, but nerve cuffs only require implantation at a single site around the nerve. This method is surgically more attractive. Nerve cuffs may also more effectively stimulate intrinsic hand muscles, which are difficult to implant and stimulate without spillover to adjacent muscles.

APPROACH

To evaluate its ability to selectively activate muscles, we implanted and tested the flat interface nerve electrode (FINE), which is designed to selectively stimulate peripheral nerves that innervate multiple muscles (Tyler and Durand 2002 IEEE Trans. Neural Syst. Rehabil. Eng. 10 294-303). We implanted FINEs on the nerves and bipolar intramuscular wires for recording compound muscle action potentials (CMAPs) from up to 20 muscles in each arm of six monkeys. We then collected recruitment curves while the animals were anesthetized.

MAIN RESULT

A single FINE implanted on an upper extremity nerve in the monkey can selectively activate muscles or small groups of muscles to produce multiple, independent hand functions.

SIGNIFICANCE

FINE cuffs can serve as a viable supplement to intramuscular electrodes in FES systems, where they can better activate intrinsic and extrinsic muscles with lower currents and less extensive surgery.

Real-Time Closed-Loop Functional Electrical Stimulation Control of Muscle Activation with Evoked Electromyography Feedback for Spinal Cord Injured Patients

Functional electrical stimulation (FES) is a neuroprosthetic technique to help restore motor function of spinal cord-injured (SCI) patients. Through delivery of electrical pulses to muscles of motor-impaired subjects, FES is able to artificially induce their muscle contractions. Evoked electromyography (eEMG) is used to record such FES-induced electrical muscle activity and presents a form of [Formula: see text]-wave. In order to monitor electrical muscle activity under stimulation and ensure safe stimulation configurations, closed-loop FES control with eEMG feedback is needed to be developed for SCI patients who lose their voluntary muscle contraction ability. This work proposes a closed-loop FES system for real-time control of muscle activation on the triceps surae and tibialis muscle groups through online modulating pulse width (PW) of electrical stimulus. Subject-specific time-variant muscle responses under FES are explicitly reflected by muscle excitation model, which is described by Hammerstein system with its input and output being, respectively, PW and eEMG. Model predictive control is adopted to compute the PW based on muscle excitation model which can online update its parameters. Four muscle activation patterns are provided as desired control references to validate the proposed closed-loop FES control paradigm. Real-time experimental results on three able-bodied subjects and five SCI patients in clinical environment show promising performances of tracking the aforementioned reference muscle activation patterns based on the proposed closed-loop FES control scheme.

Step Ergometer Training Augmented With Functional Electrical Stimulation in Individuals With Chronic Spinal Cord Injury: A Feasibility Study

Spinal cord injury (SCI) often results in loss of upright mobility and independence subsequently challenging rehabilitation practitioners for meaningful intervention strategies. The objective of this study was to evaluate the feasibility and potential impact on walking function of the stimulation and ergometer training protocol (STEP) in chronic SCI. Fourteen individuals with a chronic motor incomplete SCI (>1-year post injury) were enrolled in the study. The intervention consisted of a 12-week walking training program delivered three times per week from 20 up to 45 min in combination with 10 channels of FES on a step ergometer. Subsequent to this training, 30 min over ground walking training was performed. Ten out of the 14 participants completed the trial (71%). All participants who completed the intervention increased their walking speed by an average of 0.13 m/s (0.08) and walking endurance by an average of 117 ft (84 ft). For those who completed the trial, 50% demonstrated increases on the Walking Index for Spinal Cord Injury II by at least one level while 60% demonstrated an increase in lower extremity motor scores; all completing the Timed Up and Go Test at baseline demonstrated a reduction in time to complete during post-test evaluation. Recruitment objectives were attained. Overall retention was lower than anticipated with 29% withdrawing secondary to issues with lower extremity pain and exertional demands; however, no other adverse events occurred. Improvements in mobility outcomes generated by the STEP show promise in the context of feasibility and warrant further investigation to evaluate efficacy in comparison to other walking recovery interventions. The STEP was well-tolerated by participants who were >1 year and less than 10 years post SCI. Those completing the protocol exhibited improvements in commonly used SCI walking outcome measures.

EMG-triggered stimulation post spinal cord injury: A case report

BACKGROUND

Mechanical injury in patients with spinal cord injury (SCI) rarely transects the cord completely, even when the injury is classified as complete. These patients can show sub-clinical evidence of spared motor connections, which might be amenable to targeted rehabilitation. Neurophysiological evaluations can complement the clinical evaluation by providing objective data about conduction across the SCI site.

CASE DESCRIPTION

A twenty-four year old patient with SCI was admitted to a rehabilitation centre 49 days post traumatic SCI. His injury was categorized as motor and sensory complete (AIS A) with a neurological level of C4. The strength of his triceps bilaterally was recorded 0/5 repeatedly by his therapists during the five-month period post-injury. As a result, no training was provided for these muscles during the rehabilitation program. Neurophysiological Assessment: Motor evoked potentials (MEPs) were recorded from his left triceps with transcranial magnetic stimulation (TMS) which confirmed the existence of spared corticospinal connections to this muscle post-injury.

INTERVENTION

He completed a series of active-assisted exercises with an EMG-triggered neuromuscular stimulation (NMS) device for his left triceps comprising 20-minutes elbow extension (15 trials), three times per day for 4 weeks.

OUTCOME

The strength of his left triceps gradually improved to 2/5.

DISCUSSION

Neurophysiological evaluation can be useful in identifying residual function below the level of injury, which can, in turn, be enhanced through appropriate rehabilitation strategies.

Early intensive hand rehabilitation is not more effective than usual care plus one-to-one hand therapy in people with sub-acute spinal cord injury ('Hands On'): a randomised trial

QUESTION

What is the effect of adding an intensive task-specific hand-training program involving functional electrical stimulation to a combination of usual care plus three 15-minute sessions per week of one-to-one hand therapy in people with sub-acute tetraplegia?

DESIGN

A parallel group, randomised, controlled trial. Participants were randomly assigned (1:1) via a computer-generated concealed block randomisation procedure to either a control or experimental intervention.

PARTICIPANTS

Seventy people with C2 to T1 motor complete or incomplete tetraplegia within 6 months of injury. Participants were recruited from seven spinal units in Australia and New Zealand.

INTERVENTION

Experimental participants received intensive training for one hand. Intensive training consisted of training with an instrumented exercise workstation in conjunction with functional electrical stimulation for 1hour per day, 5 days per week for 8 weeks. Both groups received usual care and 15minutes of one-to-one hand therapy three times per week without functional electrical stimulation.

OUTCOME MEASURES

The primary outcome was the modified Action Research Arm Test reflecting arm and hand function, which was assessed at the end of the intervention, that is, 11 weeks after randomisation. Secondary outcomes were measured at 11 and 26 weeks.

RESULTS

Sixty-six (94%) participants completed the post-intervention assessment and were included in the primary intention-to-treat analysis. The mean (SD) modified Action Research Arm Test score for experimental and control participants at the post-intervention assessment was 36.5 points (SD 16.0) and 33.2 points (SD 17.5), respectively, with an adjusted mean between-group difference of 0.9 points (95% CI -4.1 to 5.9).

CONCLUSION

Adding an intensive task-specific hand-training program involving functional electrical stimulation to a combination of usual care plus three 15-minute sessions per week of one-to-one hand therapy does not improve hand function in people with sub-acute tetraplegia.

REGISTRATION

Australian and New Zealand Trial Registry ACTRN12609000695202 and ClinicalTrials.gov NCT01086930. [Harvey LA, Dunlop SA, Churilov L, Galea MP, Spinal Cord Injury Physical Activity (SCIPA) Hands On Trial Collaborators (2017) Early intensive hand rehabilitation is not more effective than usual care plus one-to-one hand therapy in people with sub-acute spinal cord injury ('Hands On'): a randomised trial. Journal of Physiotherapy 63: 197-204].

Utilizing Physiological Principles of Motor Unit Recruitment to Reduce Fatigability of Electrically-Evoked Contractions: A Narrative Review

Neuromuscular electrical stimulation (NMES) is used to produce contractions to restore movement and reduce secondary complications for individuals experiencing motor impairment. NMES is conventionally delivered through a single pair of electrodes over a muscle belly or nerve trunk using short pulse durations and frequencies between 20 and 40Hz (conventional NMES). Unfortunately, the benefits and widespread use of conventional NMES are limited by contraction fatigability, which is in large part because of the nonphysiological way that contractions are generated. This review provides a summary of approaches designed to reduce fatigability during NMES, by using physiological principles that help minimize fatigability of voluntary contractions. First, relevant principles of the recruitment and discharge of motor units (MUs) inherent to voluntary contractions and conventional NMES are introduced, and the main mechanisms of fatigability for each contraction type are briefly discussed. A variety of NMES approaches are then described that were designed to reduce fatigability by generating contractions that more closely mimic voluntary contractions. These approaches include altering stimulation parameters, to recruit MUs in their physiological order, and stimulating through multiple electrodes, to reduce MU discharge rates. Although each approach has unique advantages and disadvantages, approaches that minimize MU discharge rates hold the most promise for imminent translation into rehabilitation practice. The way that NMES is currently delivered limits its utility as a rehabilitative tool. Reducing fatigability by delivering NMES in ways that better mimic voluntary contractions holds promise for optimizing the benefits and widespread use of NMES-based programs.

Comparison of morphological changes of muscle fibers in response to dynamic electrical muscle contraction and dynamic hydraulic stimulation in a rat hindlimb disuse model

This study attempted to compare the muscle fiber morphological responses to dynamic electrical muscle stimulation (DEMS) and dynamic hydraulic stimulation (DHS) in rats under hindlimb suspension (HLS). DEMS at 1 Hz, 50 Hz and 100 Hz for 10 min/day, 5 days/week were introduced to the animals' right quadriceps. Static and 2 Hz DHS were introduced to the right tibiae of other animal groups on a "10 min on - 5 min off - 10 min on" loading regime for 5 days/week. In the end of the 4-week experiments, histological changes in the corresponding soleus, gastrocnemius and quadriceps of the stimulated sites were examined. Compared to age-matched, HLS led to muscle atrophy and strongly reduced muscle wet weights and averaged cross-sectional fiber areas. Among the tested DEMS frequencies, the averaged cross-sectional quadriceps fiber area in the 50 Hz group was 29 % larger than the 100 Hz group. In contrast, difference in the muscle fiber response to the static and 2 Hz DHS was not observed in either soleus or gastrocnemius. Muscle fiber morphological responses to the active DEMS was in a load frequency dependent manner under disuse condition. Relatively passive compressions, either via static or 2Hz DHS, were unable to induce any difference in the muscle fiber responses under functional disuse.

Effects of Electrical Stimulation on Risk Factors for Developing Pressure Ulcers in People with a Spinal Cord Injury: A Focused Review of Literature

Pressure ulcers (PUs) are a common and serious problem for wheelchair users, such as individuals with a spinal cord injury (SCI), resulting in great discomfort, loss of quality of life, and significant medical care costs. Therefore, it is of utmost importance to prevent PUs. In this literature overview, the effects of electrical stimulation (ES) on the risk factors for developing PUs in people with an SCI are examined and synthesized from January 1980 to January 2015. Thirty-four relevant studies of PU prevention in SCI were identified. Four were randomized clinical trials, 24 were case series, 6 had other designs. Three types of ES modalities were identified. The methodological quality varied from poor to fairly strong, with a large variety in used ES parameters. Twenty-three studies were identified describing short-term effects of ES on interface pressure, oxygenation, and/or blood flow, and 24 studies described the long-term effects of ES on muscle volume, muscle strength, and histology. Whereas there is a lack of controlled studies on the effects of ES on PU incidence, which disallows definite conclusions, there is moderate evidence to suggest that ES-induced muscle activation has a positive influence on several risk factors for developing PUs in people with an SCI.