Epidural stimulation of the cervical spinal cord improves voluntary motor control in post-stroke upper limb paresis

A large proportion of cerebral strokes disrupt descending commands from motor cortical areas to the spinal cord which can results in permanent motor deficits of the arm and hand[1][1],[2][2]. However, below the lesion, the spinal circuits that control movement[5][3] remain intact and could be targeted by neurotechnologies to restore movement[6][4]–[9][5]. Here we demonstrate that by engaging spinal circuits with targeted electrical stimulation we immediately improved voluntary motor control in two participants with chronic post-stroke hemiparesis. We implanted a pair of 8-contact percutaneous epidural leads on the lateral aspect of the cervical spinal cord to selectively target the dorsal roots that provide excitatory inputs to motoneurons controlling the arm and hand[10][6],[11][7]. With this strategy, we obtained independent activation of shoulder, elbow and hand muscles. Continuous stimulation through selected contacts at specific frequencies enabled participants to perform movements that they had been unable to perform for many years. Overall, stimulation improved strength, kinematics, and functional performance. Unexpectedly, both participants retained some of these improvements even without stimulation, suggesting that spinal cord stimulation could be a restorative as well as an assistive approach for upper limb recovery after stroke. ### Competing Interest Statement Authors Marc Powell, Marco Capogrosso, Douglas Weber, and Peter Gerszten are founders and shareholders of Reach Neuro, Inc. a company developing spinal cord stimulation technologies for stroke. ### Clinical Trial NCT04512690 ### Funding Statement The study was executed through the support of internal funding from the Department of Neurological Surgery at the University of Pittsburgh to Marco Capogrosso. Additional funding was provided by the Department of Mechanical Engineering and the Neuroscience Institute at Carnegie Mellon University to author Douglas Weber and the Department of Physical Medicine and Rehabilitation at the University of Pittsburgh to author Elvira Pirondini. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All experimental protocols were approved by the University of Pittsburgh Institutional Review Board (Protocol STUDY19090210) under an abbreviated IDE I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All software and anonymized data will be available upon reasonable request to the corresponding author. [1]: #ref-1 [2]: #ref-2 [3]: #ref-5 [4]: #ref-6 [5]: #ref-9 [6]: #ref-10 [7]: #ref-11