“I have regained my freedom,” summarizes this patient Gert-Jan, who does not want to give his last name. The 40-year-old Dutchman suffered a spinal cord injury in his cervical vertebrae after a bicycle accident ten years ago and can now stand up, move around varied terrain and even climb stairs.
Initially, he was unable to put one foot in front of the other, reported Swiss surgeon Jocelyne Bloch, a professor at the Vaud University Hospital, in a study published on Wednesday in the journal Nature (new window).
Before him, other patients who were unable to move their legs benefited from advances that allowed them to walk again. But for the first time, this man can again control the movement of his legs and the rhythm of his steps through thought, the study underlines.
A feat made possible by the combination of two technologies implanted in the brain and spinal cord, explains Guillaume Charvet, researcher at the Commissariat for Atomic and Alternative Energies (CEA) involved in the project, to Agence France-Presse (AFP) .
This result is the result of more than ten years of research by teams in France and Switzerland.
Algorithms based on artificial intelligence methods
Enclosed by the vertebral column, the spinal cord expands the brain and controls many movements. These can therefore be irretrievably lost if contact with the brain is damaged.
To change the situation, electrodes developed by the CEA were implanted in the paralyzed patient above the brain region responsible for leg movements.
This device makes it possible to decode the electrical signals that the brain generates when we think about walking. At the same time, a neurostimulator connected to an array of electrodes was placed over the area of the spinal cord that controls leg movement.
Thanks to algorithms based on artificial intelligence methods, movement intentions are decoded in real time from brain recordings.
These intentions are then translated into electrical stimulation sequences to the spinal cord, which in turn activate the leg muscles to perform the desired movement.
The data is transmitted via a portable system that is placed on a rollator or in a small backpack, so that the patient can do without outside help.
A first in medicine
Until now, the installation of a single implant that electronically stimulates the spinal cord has made it possible for paraplegic patients to walk again. But controlling that walk wasn’t natural.
This time, the digital bridge between the brain and the spinal cord not only allows Gert-Jan to move, but also to voluntarily control his movements and their amplitude.
“It’s radically different from what we’ve seen before,” enthuses French neuroscientist Grégoire Courtine, professor of neuroscience at the Swiss Federal Polytechnic School in Lausanne.
“Previous patients had to walk with great effort; There he only has to think of walking to take a step. »
– A quote from Grégoire Courtine, professor of neuroscience
The Dutchman, who underwent two surgeries for the two implants, recalls a long journey to being able to stand and walk for several minutes at a time again.
Another major advance: after six months of training, he appears to have recovered some of his sensory and motor skills, despite the system being disabled.
These results suggest that establishing a connection between the brain and spinal cord would promote reorganization of neural circuits at the lesion level, decodes Guillaume Charvet of the CEA.
A technology that will soon be accessible to most people? Mr Charvet complains that it will take many more years of research before a generalization can be made.
But teams are already preparing to attempt an attempt to use the same technology to restore function to the arms and hands. They hope to apply it to other clinical indications, such as paralysis caused by stroke.