A device that zaps the spinal cord gave paralyzed people better control of their hands

Fourteen years ago, a journalist named Melanie Reid attempted a jump on horseback and fell. The accident left her mostly paralyzed from the chest down. Eventually she regained control of her right hand, but her left remained “useless,” she told reporters at a press conference last week. 

Now, thanks to a new noninvasive device that delivers electrical stimulation to the spinal cord, she has regained some control of her left hand. She can use it to sweep her hair into a ponytail, scroll on a tablet, and even squeeze hard enough to release a seatbelt latch. These may seem like small wins, but they’re crucial, Reid says.

“Everyone thinks that [after] spinal injury, all you want to do is be able to walk again. But if you’re a tetraplegic or a quadriplegic, what matters most is working hands,” she said.

Reid received the device, called ARCex, as part of a 60-person clinical trial. She and the other participants completed two months of physical therapy, followed by two months of physical therapy combined with stimulation. The results, published today in Nature Medicine, show that the vast majority of participants benefited. By the end of the four-month trial, 72% experienced some improvement in both strength and function of their hands or arms when the stimulator was turned off. Ninety percent had improvement in at least one of those measures. And 87% reported an improvement in their quality of life.

This isn’t the first study to test whether noninvasive stimulation of the spine can help people who are paralyzed regain function in their upper body, but it’s important because a trial has never been done before in this number of rehabilitation centers or in this number of subjects, says Igor Lavrov, a neuroscientist at the Mayo Clinic in Minnesota, who was not involved in the study. He points out, however, that the therapy seems to work best in people who have some ability to move below the site of their injury. 

The trial was the last hurdle before the researchers behind the device could request regulatory approval, and they hope it might be approved in the US by the end of the year.

ARCex consists of a small stimulator connected by wires to electrodes placed on the spine—in this case, in the area responsible for hand and arm control, just below the neck. It was developed by Onward Medical, a company cofounded by Grégoire Courtine, a neuroscientist at the Swiss Federal Institute of Technology in Lausanne and now chief scientific officer at the company.

The stimulation won’t work in the small percentage of people who have no remaining connection between the brain and spine below their injury. But for people who still have a connection, the stimulation appears to make  voluntary movements easier by making the nerves more likely to transmit a signal. Studies over the past couple of decades in animals suggest that the stimulation activates remaining nerve fibers and, over time, helps new nerves grow. That’s why the benefits persist even when the stimulator is turned off.

The big advantage of an external stimulation system over an implant is that it doesn’t require surgery, which makes using the device less of a commitment. “There are many, many people who are not interested in invasive technologies,” said Edelle Field-Fote, director of research on spinal cord injury at the Shepherd Center, at the press conference. An external device is also likely to be cheaper than any surgical options, although the company hasn’t yet set a price on ARCex. 

“What we’re looking at here is a device that integrates really seamlessly with the physical therapy and occupational therapy that’s already offered in the clinic,” said Chet Moritz, an engineer and neuroscientist at the University of Washington in Seattle, at the press conference. The rehab that happens soon after the injury is crucial, because that’s when the opportunity for recovery is greatest. “Being able to bring that function back without requiring a surgery could be life-changing for the majority of people with spinal cord injury,” he adds.

Reid wishes she could have used the device soon after her injury, but she is astonished by the amount of function she was able to regain after all this time. “After 14 years, you think, well, I am where I am and nothing’s going change,” she says. So to suddenly find she had strength and power in her left hand—“It was extraordinary,” she says.

Onward is also developing implantable devices, which can deliver stronger, more targeted stimulation and thus could be effective even in people with complete paralysis. The company hopes to launch a trial of those next year.