Marc is the first and only person to have received the new spinal neuroprosthesis, a small device containing electrodes placed under the skin on top of his spinal cord. It works by sending bursts of electrical signals to stimulate the nerves in his spinal cord, which then activate his leg muscles. The implant is described in a new study published today in Nature Medicine.
Marc has had Parkinson’s for about three decades. Twenty years ago, he received an implant that delivered deep brain stimulation—a common treatment for this disease. Despite that, he gradually developed neurological problems that left him unable to get around. “I was forced to stop walking for three years and I was considered handicapped,” Marc said.
Then, in 2021, he enrolled in a clinical trial run by researchers at the Swiss Federal Institute of Technology in Zurich and Lausanne University Hospital to test whether a neuroprosthetic device they had developed could restore his walking ability.
The team had already tested the device on three monkeys with walking and balancing difficulties similar to those experienced by people with Parkinson’s. They implanted the devices into the monkeys’ spinal cords and also gave each monkey a brain-computer interface that allowed researchers to tell when the monkey wanted to walk. Then the researchers delivered short bursts of electrical signals through the spinal implant, ultimately restoring walking abilities in all three monkeys.
In Marc’s case, the team implanted electrodes on the top of his spinal cord and linked them to a neurostimulator placed under the skin in his abdomen. Whenever he wants to take a walk, he pushes a button on a remote control that sends wireless signals to the neurostimulator.
The neuroprosthetic device then sends bursts of electrical signals that stimulate the lumbosacral spinal cord, a region of the lower spine that activates leg muscles.
“These areas have all the motor neurons that control muscle contraction, which in turn controls movement of the legs,” says Eduardo Moraud, a neural engineer at Lausanne University Hospital who was part of the team that built the device.
Parkinson’s robs people of their quality of life: as the disease progresses, most people have trouble walking or balancing and may experience “freezing,” a temporary inability to move. For more than 20 years, people with Parkinson’s-related mobility issues have been treated using deep brain stimulation. But many people like Marc find that their symptoms persist, says Jocelyne Bloch, a coauthor of the study and a neuroscientist at the Lausanne University Hospital. So she and her team have been on the hunt for new therapies. They previously worked on one that restored walking in a person who was paralyzed as a result of spinal cord injury.
“[The new study] is another technical tour de force by this group,” says Sergey Stavisky, a neural engineer at the University of California, Davis. Stavisky, who was not involved in the study, says he is glad to see the technology working for spinal cord stimulation: “It’s significant and very exciting.”
However, it remains unclear whether the neuroprosthetic device will work in every person with Parkinson’s. “That’s a really important question to answer,” says Stavisky. Marc has had his implant for about two years. Next, the Swiss research team plans to test the device in six more people.
