Shuo-Hsiu Chang

Spasticity, a complex consequence of upper motor neuron lesions, poses challenges for clinical assessment due to its neural and mechanical origins. Traditional scales like the Modified Ashworth and Tardieu Scales provide subjective, context-limited insights, often missing spasticity’s dynamic nature. Neuromusculoskeletal (NMS) modeling offers objective, quantitative insights by integrating patient-specific muscle–tendon properties, reflex dynamics, and multi-joint biomechanics. This scoping review examines advancements in spasticity modeling, comparing mechanical, neurological, and integrated approaches, and their applications in conditions like cerebral palsy and stroke. We highlight barriers to clinical translation, including computational demands and regulatory challenges, and propose future directions, such as real-time simulation and machine learning integration, to enhance personalized assessment and treatment.

Spasticity, a complex consequence of upper motor neuron lesions, poses challenges for clinical assessment due to its neural and mechanical origins. Traditional scales like the Modified Ashworth and Tardieu Scales provide subjective, context-limited insights, often missing spasticity’s dynamic nature. Neuromusculoskeletal (NMS) modeling offers objective, quantitative insights by integrating patient-specific muscle-tendon properties, reflex dynamics, and multi-joint biomechanics. This scoping review examines advancements in spasticity modeling, comparing mechanical, neurological, and integrated approaches, and their applications in conditions like cerebral palsy and stroke. We highlight barriers to clinical translation, including computational demands and regulatory challenges, and propose future directions, such as real-time simulation and machine learning integration, to enhance personalized assessment and treatment.

To investigate the safety and feasibility of repeated transcutaneous spinal direct current stimulation (tsDCS) as priming strategy during exoskeleton-assisted locomotor training in individuals with SCI and evaluate potential neurophysiologic and functional gait changes. Case series experimental design. Research laboratory at a post-acute rehabilitation hospital. Four participants with chronic incomplete SCI. Four participants with chronic incomplete SCI received three weeks of training consisting of two types of interventions after baseline (A): 20-minute tsDCS (anode or cathode) applied over the spinous processes of T10 followed by 20-minute exoskeleton-assisted locomotor training (B, B1, B2) and 20-minute exoskeleton-assisted locomotor training (C, C1, C2). Each phase consisted of five consecutive intervention sessions. Two participants underwent sequence A-B1-C-B2 and two sequence A-C1-B-C2. Soleus Hoffmann Reflex (H-reflex) and gait speed (10-m walk test) were assessed on the first and fifth days of training for each training type. Adverse skin reactions or other events, H-reflex (Hmax/Mmax ratio), and gait speed (10-m walk test). No adverse events occurred. All participants tolerated tsDCS with no negative effects on their skin. Participants demonstrated varied responses in their H/M ratios after tsDCS followed by exoskeleton-assisted locomotor training as well as after exoskeleton-assisted locomotor training. No consistent pattern can be identified in this case series. Three participants showed an increase in gait speed after tsDCS combined with exoskeleton-assisted locomotor training. Noninvasive repeated spinal stimulation can safely be used in individuals with incomplete SCI. Further large-scale research is necessary to determine the efficacy of tsDCS for priming the spinal cord in facilitating recovery of gait in individuals with SCI.

Background/Objectives: Age-related decline in balance and postural control is common in healthy elders and is escalated in aging adults with stroke. Transcranial direct current stimulation (tDCS) has emerged as one of the promising brain stimulations adjoining therapeutic exercise to enhance the recovery of balance and motor functions in persons with and without neurological disorders. This review aims to summarize and compare the available evidence of the tDCS on improving balance in the older adults without neurological disorders and the older adults with stroke. Methods: The Ovid (Medline) database was searched from its inception through to 06/15/2024 for randomized controlled trials investigating tDCS for improving balance in older adults with and without stroke. Results: Overall, 20 appropriate studies (including 271 stroke subjects and 259 healthy older adults) were found. The data indicate mixed results of tDCS for improving balance in older adults with and without stroke. Conclusions: Based on current research evidence, we have not found a specific tDCS protocol that is more effective than other tDCS protocols for improving balance and postural control in healthy older adults and older adults with stroke. Further research should explore the ideal tDCS approach, possibly in conjunction with standard interventions, to optimize postural control and balance in healthy older adults and older adults with stroke.

While no single method effectively prevents bone loss after spinal cord injury (SCI), consistent participation in activity-based therapies can help reduce it in individuals with chronic complete SCI. This case report presents the results of multiple dual-energy X-ray absorptiometry scans conducted over 14 years, highlighting changes in bone mineral density (BMD). The individual studied maintained a healthy lifestyle, preventing secondary complications associated with SCI. The focus is on the participant’s engagement in various therapies, including functional electrical stimulation, lower-extremity cycling, and walking with a robotic exoskeleton. Remarkably, the findings indicate that, rather than losing BMD, this individual not only maintained but, in some areas, also even increased their BMD in the lower extremities. This observation contradicts the expected trend for individuals with chronic complete SCI, suggesting that activity-based therapies may yield positive outcomes.

Editorial: How can wearable robotic and sensor technology advance neurorehabilitation?

Objective: Gait deficit after multiple sclerosis (MS) can be characterized by altered muscle activation patterns. There is preliminary evidence of improved walking with a lower limb exoskeleton in persons with MS. However, the effects of exoskeleton-assisted walking on neuromuscular modifications are relatively unclear. The objective of this study was to investigate the muscle synergies, their activation patterns and the differences in neural strategies during walking with (EXO) and without (No-EXO) an exoskeleton. Methods: Ten subjects with MS performed walking during EXO and No-EXO conditions. Electromyography signals from seven leg muscles were recorded. Muscle synergies and the activation profiles were extracted using non-negative matrix factorization. Results: The stance phase duration was significantly shorter during EXO compared to the No-EXO condition (p<0.05). Moreover, typically 3-5 modules were extracted in each condition. The module-1 (comprising Vastus Medialis and Rectus Femoris muscles), module-2 (comprising Soleus and Medial Gastrocnemius muscles), module-3 (Tibialis Anterior muscle) and module-4 (comprising Biceps Femoris and Semitendinosus muscles) were comparable between conditions. During EXO condition, Semitendinosus and Vastus Medialis emerged in module-5 in 7/10 subjects. Compared to No-EXO, average activation amplitude was significantly reduced corresponding to module-2 during the stance phase and module-3 during the swing phase during EXO. Conclusion: Exoskeleton-assistance does not alter the existing synergy modules, but could induce a new module to emerge, and alters the control of these modules, i.e., modifies the neural commands indicated by the reduced amplitude of the activation profiles. Significance: The work provides insights on the potential underlying mechanism of improving gait functions after exoskeleton-assisted locomotor training.

Study design: Clinical trial. Objective: To demonstrate that a 12-week exoskeleton-based robotic gait training regimen can lead to a clinically meaningful improvement in independent gait speed, in community-dwelling participants with chronic incomplete spinal cord injury (iSCI). Setting: Outpatient rehabilitation or research institute. Methods: Multi-site (United States), randomized, controlled trial, comparing exoskeleton gait training (12 weeks, 36 sessions) with standard gait training or no gait training (2:2:1 randomization) in chronic iSCI (>1 year post injury, AIS-C, and D), with residual stepping ability. The primary outcome measure was change in robot-independent gait speed (10-meter walk test, 10MWT) post 12-week intervention. Secondary outcomes included: Timed-Up-and-Go (TUG), 6-min walk test (6MWT), Walking Index for Spinal Cord Injury (WISCI-II) (assistance and devices), and treating therapist NASA-Task Load Index. Results: Twenty-five participants completed the assessments and training as assigned (9 Ekso, 10 Active Control, 6 Passive Control). Mean change in gait speed at the primary endpoint was not statistically significant. The proportion of participants with improvement in clinical ambulation category from home to community speed post-intervention was greatest in the Ekso group (>1/2 Ekso, 1/3 Active Control, 0 Passive Control, p < 0.05). Improvements in secondary outcome measures were not significant. Conclusions: Twelve weeks of exoskeleton robotic training in chronic SCI participants with independent stepping ability at baseline can improve clinical ambulatory status. Improvements in raw gait speed were not statistically significant at the group level, which may guide future trials for participant inclusion criteria. While generally safe and tolerable, larger gains in ambulation might be associated with higher risk for non-serious adverse events.