Quadriplegic walks after implants in the brain and spinal cord – 05/24/2023 – Science

A team led by researchers from Switzerland and France managed to get a patient paralyzed by a spinal injury back to walking in a practically normal way by means of implants in the brain and spinal cord. The method is still complex and laborious, but it represents the biggest advance so far in attempts to “rewire” the movement of people with this type of paralysis.

“We were able to reestablish the interrupted connection between the brain and the spinal cord through a digital bridge”, summarized one of the study’s coordinators, Grégoire Courtine, from EPFL (Escola Politécnica Federal de Lausanne), in Switzerland. “Grégoire and I started working together on this 11 years ago and, at first, it seemed like something out of science fiction. Now it’s become reality”, added Jocelyne Bloch, a neurosurgeon also linked to the EPFL.

The duo and other authors of the study participated in an online press conference about the results, organized by the prestigious scientific journal Nature, in which details about the method have just been published. Although the Nature article describes the successful experiments with only one patient, the researchers say that the principles behind the strategy have already been validated with nine other patients, which indicates that it may work with more people with spinal injuries.

The pioneer patient –or “our first test pilot”, as Courtine prefers to say– is Dutch Gert-Jam Oskam, 40.

“I’ve been trying to get back on my feet for 12 years now,” he says. In a bicycle accident, Oskam suffered a partial cervical injury (that is, without a complete “cut” of the spinal cord, but affecting the neck region) that left him a quadriplegic. At first, he couldn’t move his legs and he also had some difficulty moving his arms and trunk.

Oskam had already been participating in testing part of the approach with the Lausanne team, involving just an implant for electrical stimulation in the lumbar region of the spinal cord. In essence, they explain, the idea was to program the device to deliver stimuli that would trigger the sequence of movements needed to walk.

The idea worked relatively well, helping the Dutch patient regain the ability to move around with a walker, but it was far from providing the naturalness of movement that natural walking includes.

To achieve this level of recovery, the researchers came up with the idea of ​​the digital bridge: a system that could “read” Oskam’s brain impulses in the area that controls leg movements and, via wireless signals, transmit these commands to the implant installed in the medulla. Thus, the cerebral control would “skip” the injured region and reach directly the neurons that command the movement below, still preserved even after the accident.

For everything to work, it was necessary to use an artificial intelligence system capable of decoding the signals coming from the brain and translating them into movement commands. The signal capture implant was inserted inside the brain, after an operation that opened small holes in the patient’s skull.

“He can walk quite naturally using the system, moving the hip, knee and ankle joints,” says Guillaume Charvet of the University of the Alps in Grenoble, France, who also helped coordinate the study. Oskam can now walk distances of up to 200 meters at a time without difficulty, as well as stand for several minutes at a time.

The devices were incorporated into the patient’s routine without the need for external supervision over several months. Their battery is recharged by a wireless system, similar to the most modern cell phones available on the market.

The study authors say there are good prospects for using the approach in patients who have paralyzed arms or trunk, as well as in people with other types of spinal cord injury or who suffer from paralysis caused by other reasons, such as strokes. The great disadvantage of the method, for now, is the need for invasive interventions in the brain and spinal cord to perform the implants. Methods that use only electroencephalography caps, placed in contact with the skin of the skull, are not able to capture such precise signals of brain activity.