For the first time, researchers have used electrical stimulation of the cervical spinal cord to immediately restore arm and hand movement in two patients with chronic moderate-to-severe upper limb paresis.
The results provide "promising, albeit preliminary, evidence that spinal cord stimulation could be an assistive as well as a restorative approach for upper-limb recovery after stroke," first author Marc P. Powell, PhD, Reach Neuro Inc., Pittsburgh, Pennsylvania, and colleagues wrote.
The findings were published online February 20 in Nature Medicine.
Top Cause of Paralysis
"Stroke is the largest cause of paralysis in the world," with nearly three quarters of patients with stroke experiencing lasting deficits in motor control of their arm and hand, co-senior study author Marco Capogrosso, PhD, assistant professor of neurological surgery at the University of Pittsburgh, Pittsburgh, Pennsylvania, said during a press briefing.
Stroke can disrupt communication between the brain and the spinal cord, leading to motor deficits in the arm and hand. However, below the lesion, the spinal circuits that control movement remain intact and could be targeted to restore function, Capogrosso noted.
Spinal cord stimulation has shown promise in promoting long-lasting recovery of leg motor function in patients with spinal cord injury; but until now, it's been largely unexplored for upper-limb recovery.
In this "first-in-human" study, the investigators percutaneously implanted two linear leads in the dorsolateral epidural space targeting neural circuits that control arm and hand muscles in two patients.
One of the patients was a woman (age, 31 years) who had experienced a right thalamic hemorrhagic stroke secondary to a cavernous malformation 9 years before enrolling in the pilot study.
The other patient was a woman (age, 47 years) who experienced a right ischemic middle cerebral artery (MCA) stroke secondary to a right carotid dissection, resulting in a large MCA territory infarct 3 years before entering the study.
In both patients, continuous stimulation of the targeted neural circuits led to significant and immediate improvement in arm and hand strength and dexterity. This enabled the patients to perform movements that they couldn't perform without spinal cord stimulation.
The process also enabled fine motor skills, such as opening a lock and using utensils to eat independently — tasks that the younger woman had not been able to do for 9 years.
"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," Capogrosso said in a news release.
No serious adverse events were reported.
Capogrosso said that, thanks to years of preclinical research, the investigators have developed a practical, easy-to-use stimulation protocol adapting existing clinical technologies that "could be easily translated to the hospital and quickly moved from the lab to the clinic."
The researchers noted, however, that further studies in larger cohorts will be required to validate the safety and efficacy of this approach.
They are currently working with more patients with stroke to fine-tune placement of the leads and stimulation protocol, as well as determine which patients are best suited for the approach.
"Creating effective neurorehabilitation solutions for people affected by movement impairment after stroke is becoming ever more urgent," co-senior author Elvira Pirondini, PhD, assistant professor of physical medicine and rehabilitation at the University of Pittsburgh, said in the release.
"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," she added.
This research was funded by the National Institutes of Health BRAIN Initiative, with additional research support provided by the Department of Neurological Surgery and the Department of Physical Medicine and Rehabilitation at Pitt, and the Department of Mechanical Engineering and the Neuroscience Institute at Carnegie Mellon University. Three investigators have financial interests in Reach Neuro, Inc., which has an interest in the technology being evaluated in this study.
Nature Med. Published online February 20, 2023. Abstract.
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Lead image: Tim Betler/UPMC and Pitt Health Sciences
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Cite this: Spinal Cord Stimulation Restores Post-Stroke Arm, Hand Function in Two Patients - Medscape - Feb 23, 2023.