Spinal Cord Stimulation Restores Arm and Hand Movement After Stroke
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People affected by moderate to severe stroke could benefit from a neurotechnology device that stimulates the spinal cord, suggests a new study.
The paper was authored by researchers from the University of Pittsburgh and Carnegie Mellon University and was published in Nature Medicine.
Co-senior author Marco Capogrosso, assistant professor of neurological surgery at the University of Pittsburgh, outlined the team’s discoveries: “We discovered that electrical stimulation of specific spinal cord regions enables patients to move their arm in ways that they are not able to do without the stimulation. Perhaps even more interesting, we found that after a few weeks of use, some of these improvements endure when the stimulation is switched off, indicating exciting avenues for the future of stroke therapies.”
The future of stroke medicine has an ominous outlook: 1 in 4 adults over 25 will have a stroke during their lifetime. More than half of patients over 65 will have reduced mobility post-stroke. Early treatment for stroke is essential. No current treatments have proved effective in treating patients more than six months post-stroke. “Even mild deficits resulting from a stroke can isolate people from social and professional lives and become very debilitating, with motor impairments in the arm and hand being especially taxing and impeding simple daily activities, such as writing, eating and getting dressed,” said senior co-author Elvira Pirondini, an assistant professor of physical medicine and rehabilitation at the University of Pittsburgh. Pirondini, Capogrosso and colleagues hope that their intervention could brighten this grim picture.
Electrifying stroke recovery
Their new intervention relies on two thin electrodes. These long, metal noodles are implanted along a patient’s neck to stimulate neural circuits in the spinal cord that remain undamaged after the stroke with pulses of electricity. Elsewhere, this technology has been used to restore leg movement after spinal cord injury and to relieve persistent, high-level pain. But the complex and fine motor movements controlled by the human hand and the interplay of neural signals between the arm and hand made restoring functionality to this area a greater challenge.
The results have been striking; for the first time in years, stroke patients have been able to open and close their fists fully, use a fork and knife to cut a piece of steak and lift their arm above their head.
By using electrical stimulation of the spinal cord, researchers from the University of Pittsburgh and Carnegie Mellon University help restore arm and hand movement in patients who survived severe strokes. Credit: Tim Betler, UPMC and University of Pittsburgh Schools of the Health Sciences
The research follows years of preclinical studies that included animal testing in non-human primates and computer modeling.
This groundwork has helped develop a fine-tuned therapy. Douglas Weber, professor of mechanical engineering at the Neuroscience Institute at Carnegie Mellon University and co-senior author of the study, commented, “The sensory nerves from the arm and hand send signals to motor neurons in the spinal cord that control the muscles of the limb. By stimulating these sensory nerves, we can amplify the activity of muscles that have been weakened by stroke. Importantly, the patient retains full control of their movements: The stimulation is assistive and strengthens muscle activation only when patients are trying to move.”
The researchers tested out their intervention by having patients complete tasks of varying complexity, including:
- Moving a hollow metal cylinder
- Grasping a can of soup
- Opening a lock
Long-lasting benefits
The tests showed that participants responded to the stimulation with improved strength, range of movement and function in the arm and hand. These benefits lasted even after the stimulation device was removed, suggesting that it has both assistive and restorative potential, especially in combination with intense physical training regimens that are enabled by the stimulation.
The team is planning future studies with additional trial participants. They are aiming to develop the therapy for different levels of impairment and then translate it into clinical use. “Thanks to years of preclinical research building up to this point, we have developed a practical, easy-to-use stimulation protocol adapting existing FDA-approved clinical technologies that could be easily translated to the hospital and quickly moved from the lab to the clinic,” said Capogrosso.
Reference: Powell MP, Verma N, Sorensen E, et al. Epidural stimulation of the cervical spinal cord for post-stroke upper-limb paresis. Nat Med. 2023:1-11. doi: 10.1038/s41591-022-02202-6
This article is a rework of a press release issued by the University of Pittsburgh. Material has been edited for length and content.
