Elicited upper limb motions through transcutaneous cervical spinal cord stimulation

Objective. Transcutaneous cervical spinal cord stimulation (tsCSC) has been demonstrated to activate the dorsal root and activate targeted muscles. However, it is unclear whether tsCSC can elicit functionally relevant movements of the upper limb for assistive/rehabilitative purposes. Approach. The current study sought to elicit arm and hand movements by tsCSC by placing an electrode array near the cervical segments of the spinal cord. Anode stimulation current pulses were delivered to the dorsal side at 120 Hz and 30 Hz in separate trials. The elicited joint kinematics were captured using a motion tracking system. Main results. The results revealed that distal and proximal joint movements can be elicited either independently or synergistically. Specifically, different motions, including flexion and extension of the elbow, wrist, and five digits, can be selectively elicited by adjusting the stimulation parameters, such as stimulation location and stimulation intensity. Significance. The findings demonstrated the feasibility of the spinal cord stimulation technique in eliciting functional movements of the upper limb. The outcomes also revealed the potential of the tsCSC technique as a promising assistive or rehabilitative method for individuals with impaired function of the upper limb.