"I have regained freedom," said Gert-Jan, who did not wish to give his last name. Suffering from a spinal cord injury in the cervical vertebrae following a bicycle accident a decade ago, this 40-year-old Dutchman can now stand, move on various terrains and even climb stairs.

"Initially, he was unable to put one foot in front of the other," said Swiss surgeon Jocelyne Bloch, a professor at the University Hospital of Vaud, presenting a study published Wednesday in the journal Nature.

Before him, other patients who could no longer move their legs benefited from advances allowing them to walk again. But for the first time, this man can again control by thought the movement of his legs and the rhythm of his steps, says the study.

A feat made possible by the combination of two technologies implanted in the brain and spinal cord, explains to AFP Guillaume Charvet, researcher at the CEA (Alternative Energies and Atomic Energy Commission), stakeholder in the project.

This result is the result of more than ten years of research by teams in France and Switzerland.

The spinal cord, contained by the spine, prolongs the brain and controls many movements. The latter can therefore be irretrievably lost if contact with the brain is damaged.

Digital bridge

To change the situation, electrodes developed by the CEA were implanted in the paralyzed patient, above the region of the brain that is responsible for leg movements.

Grégoire Courtine, professor of neuroscience at the Ecole Polytechnique Fédérale de Lausanne, at a press conference in Lausanne on May 23, 2023 © Fabrice COFFRINI / AFP

This device makes it possible to decode the electrical signals generated by the brain when we think about walking. At the same time, a neurostimulator connected to an electrode field was positioned on the region of the spinal cord that controls the movement of the legs.

Thanks to algorithms based on artificial intelligence methods, movement intentions are decoded in real time from brain recordings.

These intentions are then converted into electrical stimulation sequences of the spinal cord, which in turn activate the leg muscles to achieve the desired movement.

The data is transmitted via a portable system placed on a walker or in a small backpack, allowing the patient to dispense with outside help.

Until now, the installation of a single implant electronically stimulating the spinal cord has allowed paraplegic patients to walk again. But the control of this march was not natural.

This time, the digital bridge created between the brain and spinal cord allows Gert-Jan not only to move but also to voluntarily control his movements and their amplitude.

"Long journey"

"It's radically different from what we've seen so far," enthuses French neuroscientist Grégoire Courtine, professor of neuroscience at the Ecole Polytechnique Fédérale de Lausanne. "Previous patients walked with a lot of effort; There he just needs to think about walking to take a step."

Gert-Jan, during a press conference in Lausanne on May 23, 2023 © Fabrice COFFRINI / AFP

Operated twice for the placement of the two implants, the Dutchman evokes "a long journey" to manage to stand again and walk several minutes in a row.

Another important breakthrough: after six months of training, he seems to have recovered some of his sensory and motor faculties, even though the system is disabled.

"These results suggest that the establishment of a link between the brain and the spinal cord would promote a reorganization of neural circuits at the level of the lesion," explains Guillaume Charvet, CEA.

A technology soon accessible to as many people as possible? "It will still take many years of research" before its generalization, tempers Mr. Charvet.

But the teams are already preparing to launch a trial to restore, with the same technology, the function of the arms and hands. They also hope to apply it to other clinical indications, such as paralysis caused by a stroke.

© 2023 AFP