Soft robotics and functional electrical stimulation advances for restoring hand function in people with SCI: a narrative review, clinical guidelines and future directions.

BACKGROUND: Recovery of hand function is crucial for the independence of people with spinal cord injury (SCI). Wearable devices based on soft robotics (SR) or functional electrical stimulation (FES) have been employed to assist the recovery of hand function both during activities of daily living (ADLs) and during therapy. However, the implementation of these wearable devices has not been compiled in a review focusing on the functional outcomes they can activate/elicit/stimulate/potentiate. This narrative review aims at providing a guide both for engineers to help in the development of new technologies and for clinicians to serve as clinical guidelines based on the available technology in order to assist and/or recover hand function in people with SCI. METHODS: A literature search was performed in Scopus, Pubmed and IEEE Xplore for articles involving SR devices or FES systems designed for hand therapy or assistance, published since 2010. Only studies that reported functional outcomes from individuals with SCI were selected. The final collections of both groups (SR and FES) were analysed based on the technical aspects and reported functional outcomes. RESULTS: A total of 37 out of 1101 articles were selected, 12 regarding SR and 25 involving FES devices. Most studies were limited to research prototypes, designed either for assistance or therapy. From an engineering perspective, technological improvements for home-based use such as portability, donning/doffing and the time spent with calibration were identified. From the clinician point of view, the most suitable technical features (e.g., user intent detection) and assessment tools should be determined according to the particular patient condition. A wide range of functional assessment tests were adopted, moreover, most studies used non-standardized tests. CONCLUSION: SR and FES wearable devices are promising technologies to support hand function recovery in subjects with SCI. Technical improvements in aspects such as the user intent detection, portability or calibration as well as consistent assessment of functional outcomes were the main identified limitations. These limitations seem to be be preventing the translation into clinical practice of these technological devices created in the laboratory.

Effects of Electrical Stimulation Training on Body Composition Parameters After Spinal Cord Injury: A Systematic Review.

OBJECTIVE: To determine the effects of neuromuscular electrical stimulation (NMES) or functional electrical stimulation (FES), or both, training on different body composition parameters in individuals with spinal cord injury. DATA SOURCES: Three independent reviewers searched PubMed, Web of Science, Scopus, Cochrane Central, and Virtual Health Library until March 2020. STUDY SELECTION: Studies were included if they applied NMES/FES on the lower limb muscles after spinal cord injury, reported stimulation parameters (frequency, pulse duration, and amplitude of current), and body composition parameters, which included muscle cross-sectional area (CSA), fat-free mass, lean mass (LM), fat mass, visceral adipose tissue, and intramuscular fat. DATA SYNTHESIS: A total of 46 studies were included in the final analysis with a total sample size of 414 subjects. NMES loading exercise and FES cycling exercise were commonly used for training. Increases in muscle CSA ranged from 5.7-75%, with an average of 26% (n=33). Fifteen studies reported changes (both increase and decrease) in LM or fat-free mas ranged from -4% to 35%, with an average of less than 5%. Changes in fat mass (n=10) were modest. The effect on ectopic adipose tissue is inconclusive, with 2 studies showing an average reduction in intramuscular fat by 9.9%. Stimulation parameters ranged from 200-1000 µs for pulse duration, 2-60 Hz for the frequency, and 10-200 mA in amplitude. Finally, increase in weekly training volumes after NMES loading exercise resulted in a remarkable increase in percentage changes in LM or muscle CSA. CONCLUSIONS: NMES/FES is an effective rehabilitation strategy for muscle hypertrophy and increasing LM. Weekly training volumes are associated with muscle hypertrophy after NMES loading exercise. Furthermore, positive muscle adaptations occur despite the applied stimulation parameters. Finally, the included studies reported wide range of stimulation parameters without reporting rationale for such selection.

The Effects of Electrical Stimulation Parameters in Managing Spasticity After Spinal Cord Injury: A Systematic Review.

Controversial findings about the effects of neuromuscular electrical stimulation and functional electrical stimulation in managing spasticity have been raised after spinal cord injury. A systematic review was conducted to identify the range of the stimulation parameters that may alleviate spasticity. Three independent reviewers searched Medline (PubMed), web of knowledge, Scopus, Cochrane Central, Virtual Health Library, and Physiotherapy Evidence Database until January 2018. Inclusion criteria were applications of neuromuscular electrical stimulation/functional electrical stimulation on the lower limb muscles, stimulation parameters (frequency, pulse duration, and amplitude of current), and measures of spasticity after spinal cord injury. The primary outcome was spasticity as measured by the Modified Ashworth Scale and the secondary outcome was spasticity assessed by other indirect measures. Twenty-three clinical and nonclinical trials were included with 389 subjects. Neuromuscular electrical stimulation/functional electrical stimulation provided reductions in spasticity by 45%-60% with decrease in electromyography activity and increase in range of motion after spinal cord injury. The identified stimulation parameters were frequency of 20-30 Hz, pulse duration of 300-350 µs, and amplitude of the current greater than 100 mA. Neuromuscular electrical stimulation/functional electrical stimulation provides an effective rehabilitation strategy in managing spasticity. However, a recommendation of the stimulation parameters cannot be accurately assumed because of high variability in the methodology, design, and heterogeneity of the included studies.

Effects of Neuromuscular Electrical Stimulation in People with Spinal Cord Injury.

INTRODUCTION: Muscle force production is usually impaired in people with spinal cord injury (SCI). The use of high-intensity neuromuscular electrical stimulation (NMES) strength training can help promote metabolically active lean muscle mass and, thus, increase muscle mass and improve physical health and quality of life (QoL). Nonetheless, NMES is usually used at low-stimulation intensities, and there is limited evidence on the effects of high-intensity NMES strength training into improving muscle force and mass, symptoms of spasticity, or physical health and QoL in people with SCI. METHODS: Five individuals with chronic SCI completed five 10-repetition sets of high-intensity knee extension NMES strength training sessions for 12 wk in both quadriceps muscles. Quadriceps femoris (QF) knee extensor torque was measured on a dynamometer, and cross-sectional area (CSAQF) was measured with extended field-of-view ultrasonography. Venous blood samples were collected for blood lipid profiling and C-reactive protein analyses. The Spinal Cord Injury Spasticity Evaluation Tool was used to assess symptoms of spasticity, and the QoL index SCI version III was used for QoL measures. RESULTS: QF tetanic knee extensor torque increased on average by 35% (2%-92%), and CSAQF increased by 47% (14%-145%). A significant increase in the HDL/LDL cholesterol ratio (P < 0.001) and a mean significant improvement of 4.8% ± 2.3% (absolute value = 0.26) in the Spinal Cord Injury Spasticity Evaluation Tool score was observed, whereas QoL showed a near-significant improvement in the health and functioning domain (15.0 ± 4.2 and 17.3 ± 5.1; P = 0.07). CONCLUSIONS: High-intensity NMES strength training in people with SCI may improve muscle strength, mass, physical health, and QoL. However, replication of these results is necessary before clinical implementation.

Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

BACKGROUND: Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. METHODS: Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 µs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. RESULTS: Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no statistically significant differences between these sub-groups or between conditions when the data were pooled. CONCLUSIONS: Based on the present results there is insufficient evidence to conclude that patellar tendon vibration provides a clear benefit to muscle force production or delays muscle fatigue during wide-pulse width, moderate-intensity NMES in people with SCI. TRIAL REGISTRATION: ACTRN12618000022268 . Date: 11/01/2018. Retrospectively registered.