Spinal cord stimulation for upper limb motor function in people with chronic post-stroke hemiparesis: a feasibility trial

Chronic arm and hand hemiparesis is a major cause of disability after stroke. Unfortunately, standard-of-care rehabilitation falls well short of the high doses required to experience improvements. In this feasibility study, we explored the use of cervical epidural spinal cord stimulation (SCS) to assist motor function and provide meaningful functional improvements without the need of a high-dose rehabilitation program. Here we report the final outcomes of this study testing safety, feasibility and preliminary efficacy of cervical SCS as a neuroprosthetic approach for chronic post-stroke upper limb hemiparesis. We implanted seven participants with profound motor deficits (Fugl-Meyer Assessment (FMA) scores 15-35) using two leads implanted unilaterally in the cervical spinal cord for 4 weeks. No serious adverse events occurred. Under SCS ON, motor function immediately improved regardless of impairment severity (average +32% strength and +5.6 FMA points). Notably, three of seven participants with residual corticospinal connectivity to finger muscles improved hand/finger movement with SCS. Despite performing only 8.6 hours of motor activity (5.5 hours with SCS ON), participants improved by an average of +6.6 FMA points at the end of the study compared to baseline, and spasticity decreased in all participants. Although all benefited, our preliminary analysis indicates that spared sensory function may be a determinant of responsiveness to SCS. These findings provide preliminary evidence of the safety, feasibility and efficacy of cervical SCS for chronic post-stroke hemiparesis, suggesting its potential as a fully implantable neuroprosthetic solution for assisting upper limb function in daily living. ClinicalTrials.gov identifier: NCT04512690 .