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Neuromodulatory effects of voluntary-motor-effort-driven wrist-hand robot in sensorimotor dynamics after stroke
Yunxia Huo1,2, Weidong Li3, Fanjie Ding1
1School of Life Science and Technology, Northwestern Polytechnical University, Xi'an, China.
Background:
Voluntary motor effort (VME)-driven neuromuscular electrical stimulation (NMES)-robots have demonstrated superior rehabilitative efficacy in post-stroke wrist-hand motor restoration compared with purely mechanical systems. However, their neuromodulatory mechanisms remain unclear. This study aimed to investigate cortical responses elicited by an electromyography (EMG)-driven NMES-robot assisting wrist-hand movements in individuals with chronic stroke, and to evaluate robot-nervous system interactions, using EMG to capture VME.
Methods:
Cortical responses during wrist-hand extension were recorded in participants with chronic stroke (n = 18) and unimpaired controls (n = 20) using functional near-infrared spectroscopy (fNIRS). The EMG-driven NMES-robot delivered somatosensory stimulation with different combinations of mechanical stimulation (MS) to the targeted joints and NMES to the forearm muscles, with or without VME.
Results:
Combined MS and NMES co-stimulation activated wider cortical areas than MS or NMES alone in both groups. Compared with the unimpaired group, the stroke group exhibited greater ipsilesional activations in response to NMES (p < 0.05), while MS induced comparable activations in the contralateral hemisphere to the stimulated limb in both groups (p < 0.05). When VME was required, the stroke group exhibited wider contralesional involvement with MS only (p < 0.05) but reduced contralesional involvement during sole NMES (p < 0.05), compared to those in the co-stimulation. Additionally, the MS and NMES co-stimulation resulted in similar functional connectivity patterns between the stroke and unimpaired groups.
Conclusion:
Combined mechano-electrical somatosensory co-stimulation with MS and NMES to the affected wrist-hand, when voluntary motor effort is generated from the residual muscles, could elicit extensive cortical activation approaching normal patterns.
Trial Registration:
Chinese Clinical Trial Registry with the identifier ChiCTR2200057839.
