“A few months ago, for the first time after ten years I was able to stand up and have a beer with my friends so that was pretty cool,” says Gert-Jan, who is 40. “This simple pleasure represents a significant change in my life.”
Gert-Jan was left completely paralysed from the waist down by a spinal cord injury after a bicycle accident. Today he can stand, walk and climb stairs. A Swiss-led research team reported the result on May 24, 2023, and published it in the journal Nature.
A bridge past the injury
Jocelyne Bloch of Lausanne University Hospital (CHUV) remembers where he started. “When we met Gert-Jan he was unable to take a step after a severe spinal cord injury,” she says. In his case the link between the brain and the part of the spinal cord that controls the legs had been cut.
The team’s answer is a “digital bridge,” a brain-computer interface that turns thought into action. Surgeons placed electrodes above the area of the brain that governs leg movement. A neurostimulator wired to an electrode array went onto the stretch of spinal cord that drives the legs.
The brain implants pick up his intention to move and pass it to a device that converts it into stimulation, explains Grégoire Courtine, a professor of neurosciences at the Swiss Federal Institute of Technology Lausanne (EPFL). “For the first time this digital bridge will bypass an injury and restore the communication between two regions of the central nervous system that are disconnected,” Courtine says.
Guillaume Charvet heads the brain-computer interface program at CEA, the French government-funded technology research organisation that also worked on the project. He describes the process in more detail. Algorithms built on adaptive artificial intelligence decode movement intentions from brain recordings in real time. Those intentions become sequences of electrical stimulation to the spinal cord, which activate the leg muscles. “This digital bridge operates wirelessly, allowing the patient to move around independently,” Charvet says.
Recovery beyond the device
The bridge gave Gert-Jan natural control over legs that had not obeyed him for years. Rehabilitation with the system also brought back some neurological function lost since the accident. The researchers measured clear gains in his sensory perception and motor skills, and those gains held even with the bridge switched off. They say that points to new nerve connections having formed.
Work is continuing. The scientists think the approach could be adapted to restore arm and hand function, and to help people paralysed after a stroke. They are developing a commercial version with the company ONWARD Medical.
