PITTSBURGH, June 4, 2026 – University of Pittsburgh School of Medicine researchers report the final outcomes of a pioneering pilot clinical trial using electrical stimulation of the spinal cord to improve arm and hand mobility in people with chronic stroke today in Nature Medicine .
The study, which was primarily focused on investigating safety and preliminary efficacy, showed that seven participants with profound muscle weakness due to stroke experienced an average 32% increase in arm strength, along with improvement in overall arm mobility and reduction in muscle spasticity. Importantly, the intervention required fewer than nine hours of movement-based training over four weeks and did not cause discomfort or serious adverse events.
"This approach is designed to rapidly help people move their arms better, even years after a stroke," said co-senior author Marco Capogrosso, Ph.D., assistant professor of neurological surgery at Pitt and director of the spinal cord stimulation laboratory at Rehab Neural Engineering Labs in the UPMC Rehabilitation Institute . "The stimulation works mostly as an assistive technology — when it's on, people can move better. By stimulating the spinal cord, we can immediately allow residual connections between the brain and the spinal cord to work more efficiently, enabling better movement."
Stroke is the leading cause of adult arm paralysis in the United States, with approximately 400,000 people developing chronic arm and hand weakness each year. Many stroke survivors rank recovery of arm function as their top unmet clinical need, yet standard rehabilitation rarely drives meaningful improvement.
To address this gap, Pitt researchers launched a first-of-its-kind pilot clinical study to test whether epidural spinal cord stimulation delivered to the region controlling arm and hand movement could help stroke survivors regain arm function. The project, named among one of the most significant innovations supported by the National Institute of Neurological Disorders and Stroke (NINDS) in their 75th anniversary report, relies on technology called cervical epidural spinal cord stimulation, which involves implanting thin electrodes along the neck region of the spinal cord.
Stimulation sends targeted electrical signals to sensory nerve fibers in the spinal cord to enhance communication between the brain and weakened muscles. The same class of device has been used for decades to treat chronic pain, but this is the first time it has been used to restore arm function after stroke. The newly published study expands on earlier findings reported by the team in 2023 and confirms that the approach is safe and feasible across participants of different ages, sexes and racial backgrounds.
Researchers observed two distinct types of benefit. Over the four-week study period, all seven research participants experienced immediate improvements in strength when stimulation was turned on, regardless of how severe their impairment was at baseline. Additionally, spasticity — abnormal muscle stiffness caused by stroke-damaged nerve pathways — was reduced in all seven participants.
"From a clinical perspective, even modest improvements in arm strength or control can make a meaningful difference in daily life of stroke survivors," said study co-author George Wittenberg, M.D., Ph.D., professor of neurology and physical medicine and rehabilitation at Pitt's School of Medicine. "Some of the improvements we measure may look small from the outside, but many stroke survivors are just on the verge of being able to do something important. Even a small change in motor function can be very significant if it helps someone button a shirt, open their hand or return to an activity they care about.
While improvements were immediate, the researchers found that lasting gains depended on continued use of stimulation. Follow-up assessments showed that motor function declined when stimulation was discontinued, underscoring the potential of spinal cord stimulation as an assistive neuroprosthetic technology rather than a short-term rehabilitation aid.
"This study represents the conclusion of our initial feasibility phase and an important step toward real-world clinical application," Capogrosso said. "Our goal is to develop a technology that could eventually be used in everyday life, not just in the clinic. These results give us confidence that spinal cord stimulation could become a practical, implantable option for helping stroke survivors use their arms when it matters most."
Building on these findings, the research team has begun recruiting participants for an extended clinical trial to evaluate the effects of longer-term spinal cord stimulation, both alone and in combination with physical therapy .
University of Pittsburgh authors of this research include Roberto de Freitas, Ph.D., Shovan Bhatia, Ph.D., Erynn Sorensen, Ph.D., Erick Carranza, Ph.D., Scott Ensel, Ph.D., Amy Boos, OTL/R, M.S., Lee Fisher, Ph.D., Daryl Fields, Ph.D., Marc Powell, Ph.D., Jeffrey Balzer, Ph.D., Peter Gerszten, M.D., and Elvira Pirondini, Ph.D. Additional co-authors are from Carnegie Mellon University, Columbia University, the Veterans Affairs Pittsburgh Healthcare System and Johns Hopkins University.
This research was supported by the National Institutes of Health BRAIN Initiative (grant UG3NS123135‑01A1), internal funding from the departments of Neurological Surgery and Physical Medicine and Rehabilitation at Pitt, as well as the Department of Mechanical Engineering and the Neuroscience Institute at Carnegie Mellon University .
