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Spinal cord stimulation improves arm, hand movements after stroke

Stroke is a leading cause of death and the most common cause of long-term adult disability in the United States. Nearly three-quarters of people worldwide who suffer a stroke will have lasting loss of arm and hand movement. This loss of motor control can greatly hinder everyday activities. There are no effective treatments for chronic paralysis that lingers beyond six months after stroke.

Over the past decade, several NIH-supported studies have reported success in using a technique called spinal cord stimulation to improve limb movement in people after spinal cord injury. The approach involves surgically implanting thin metal electrodes onto the surface of the spinal cord and then delivering electrical impulses. The impulses are designed to amplify weakened nerve pathways that control movement.

To date, most of these studies have focused on improving leg movement and walking after spinal cord injury. In a new “first-in-human” study, a research team based at the University of Pittsburgh explored using spinal cord stimulation to improve upper-limb movement in people with partial paralysis after a stroke. Results of a pilot study involving two patients were reported on February 20, 2023, in Nature Medicine.

Both study participants were female. One, age 31, had a stroke nine years earlier. The other, age 47, had a stroke three years earlier. Each received implants of two electrode arrays in the upper (neck) region of the spinal cord, called the cervical spine.

The researchers found that continuous electrode stimulation, tailored for each participant, immediately improved strength, function, and range of movement in the participants’ arms and hands. Stimulation also enabled the return of fine motor skills. With the stimulation turned on, participants could perform tasks that they hadn’t been able to do for years, such as opening a lock, eating with a fork, or grasping and lifting a can of soup.

When the electrodes were removed after 29 days, the researchers were surprised to see that some improvements remained for weeks afterward. No serious side effects were seen during the study.

“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,” says study co-senior author Dr. Marco Capogrosso. “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 researchers note that larger studies will be needed to assess the safety and effectiveness of this approach to improving upper-limb paralysis after stroke.