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How Implanted Electrodes Helped Paralyzed People Stand and Walk Again

Two new studies demonstrate that epidural stimulation and intensive therapy can help people overcome paralysis from spinal cord injuries

Study participants Kelly Thomas, who was paralyzed in a truck crash and Jeff Marquis, who was injured while mountain biking. (University of Louisville)
smithsonian.com

There are about 1.3 million people in the United States paralyzed by spinal cord injuries, and for the vast majority, there is little hope that they will ever regain the use of their affected limbs. But a new research suggests researchers may have found a possible treatment for paralysis. Rachel Becker at The Verge reports that in two new studies, scientists implanted electrodes near the spines of patients, giving some the ability to walk after weeks of electrical stimulation and physical therapy.

In the first study in The New England Journal of Medicine, researchers from the Kentucky Spinal Cord Injury Research Center at the University of Louisville implanted a device called an epidural stimulator near the spines of four paralyzed patients. Each was at least 2.5 years post-accident and none of them had the ability to stand, walk or voluntarily move their legs.

According to a press release, the participants went through over two months of intense physical therapy before the devices were implanted, including two hours of training each day on a treadmill. However, after that training none of them showed any signs of recovering the ability to move or walk. They were each implanted with the stimulator, which includes 16 electrodes. Two of the patients regained the ability to stand and take a step. The other two participants regained the ability to walk with assistance.

In another study published in the journal Nature Medicine, researchers from the Mayo Clinic and UCLA implanted a similar device in the back of a 29-year-old man paralyzed in a snowmobiling accident in 2013. After 113 rehabilitation sessions over 43 weeks, he also regained some function, and was eventually able to walk the length of a football field and stay upright 16 minutes at a time.

Becker reports that both studies used off-the-shelf devices originally designed for pain management. Researchers realized that oftentimes in spinal cord injuries, paralysis occurs because the brain can no longer communicate its intentions to the legs, or that the signal is too weak to stimulate movement. However, studies show that if the spinal cord is electrically stimulated, it can act as a booster amplifying the brain’s signals to the legs. “It is like it is more aware, it actually can listen to that little whisper from the brain that is still there and it can generate the motor pattern,” co-author Claudia Angeli of the University of Louisville tells Nicola Davis at The Guardian.

The improvements, however, were not immediate. Each participant went through intense physical therapy after receiving the stimulator. In the Louisville study, one participant that regained the ability to stand suffered a spontaneous hip fracture during the research. Kelly Thomas, a participant in the Louisville study, was paralyzed several years ago in Florida after her truck flipped and she hit her head. She is now able to walk over uneven ground with a walking frame when her stimulator is turned on.

“It’s not a quick fix to being paralyzed. You don’t turn it on and you’re just automatically back to where you were pre-injury,” she tells Becker at The Verge. “You have to figure out how to use it, how to work with your body again.”

These new studies serve as an exciting proof of concept and mark the first time people with spinal cord injuries recovered that functional walking.

“While more clinical research must be done with larger cohorts, these findings confirm that the spinal cord has the capacity to recover the ability to walk with the right combination of epidural stimulation, daily training and the intent to step independently with each footstep,” Angeli says in the release.

Davis at The Guardian reports that while others working to repair spinal cord injuries applaud the new research, some believe the electrode stimulation approach has limitations since the electrodes are continuously on and may not be able to relay more subtle commands from the brain. To get around that, some researchers are looking at brain implants that bypass the spinal cord to relay information. Another group of researchers is looking at using specialized cells from the patient's body to “patch” injured nerve fibers at the site of the injury.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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