Spinal Cord Stimulation Improves Arm Motor Function After Stroke

Partial paralysis of the arms and hands remains one of the leading causes of disability after a stroke. Despite advances in rehabilitation, current programs do not always allow for the high doses of therapy needed to achieve significant improvements. A recent study explores a new approach: electrical stimulation of the cervical spinal cord to restore motor function without requiring intensive rehabilitation.

Seven individuals with severe and chronic motor impairments following a stroke participated in this study. Electrodes were implanted in their cervical spinal cord for four weeks. No serious adverse effects were reported. From the moment the stimulation was activated, an immediate improvement in motor function was observed in all participants, with an average 32% increase in muscle strength and a 5.6-point improvement on the standardized assessment scale. Three out of seven participants, who had residual connectivity between the brain and the finger muscles, even regained more precise hand and finger movements.

Although participants only performed 8.6 hours of motor activity, including 5.5 hours with the stimulation activated, their performance improved by an average of 6.6 points on the assessment scale by the end of the study compared to the beginning. Additionally, a reduction in spasticity—the muscle stiffness characteristic after a stroke—was observed in all participants. The results also suggest that the preservation of sensory function could be a key factor in determining who will respond best to this therapy.

This approach paves the way for an implantable neuroprosthetic solution to help individuals regain greater independence in their daily lives. Unlike traditional methods that aim to enhance the effects of rehabilitation, this technique acts directly on the nervous system to facilitate movement, offering immediate and lasting results. The most significant improvements were observed when the stimulation was activated, confirming its potential as a permanent tool to compensate for post-stroke motor deficits.

Researchers also noted that this method could be particularly beneficial for individuals whose brain injuries severely limit movement. By specifically targeting the segments of the spinal cord associated with the arm and hand muscles, the stimulation partially bypasses the damage caused by the stroke. Participants reported concrete improvements in daily tasks, such as holding objects or performing precision gestures, demonstrating the practical impact of this technology.

Finally, this study shows that spinal cord stimulation could represent a promising alternative to current spasticity treatments, which are often costly and invasive. The observed reductions in muscle stiffness rival those achieved by other methods, but with the advantage of a reversible and adjustable approach tailored to individual needs.

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DOI: https://doi.org/10.1038/s41591-026-04435-1

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

Journal: Nature Medicine

Publisher: Springer Science and Business Media LLC

Authors: Roberto M. de Freitas; Shovan Bhatia; Erynn Sorensen; Nikhil Verma; Erick Carranza; Scott Ensel; Luigi Borda; Amy Boos; Jeff Goldsmith; Lee E. Fisher; Daryl P. Fields; Marc P. Powell; Shane Gordon; Jeffrey Balzer; Robert M. Friedlander; George F. Wittenberg; Peter C. Gerszten; John W. Krakauer; Elvira Pirondini; Douglas J. Weber; Marco Capogrosso