Brain and spinal implants allow paralyzed man to walk naturally again

Gert-Jan Oskam was living in China in 2011 when he had a motorcycle accident that left him paralyzed from the hips down. Now, with a combination of devices, scientists have given him back control of his lower body.

“For 12 years I tried to get back on my feet,” Mr. Oskam said during a press briefing on Tuesday. “Now I have learned to walk normally, naturally.”

In a study published Wednesday in the journal Nature, Swiss researchers described implants that provided a “digital bridge” between Mr. Oskam’s brain and his spinal cord, bypassing injured sections. The discovery allowed Mr Oskam, 40, to stand, walk and climb a steep ramp with only the aid of a walker. Over a year after the implant was inserted, he retained these abilities and in fact showed signs of neurological recovery, walking on crutches even when the implant was off.

“We captured Gert-Jan’s thoughts and translated those thoughts into spinal cord stimulation to restore voluntary movement,” Grégoire Courtine, a spinal cord specialist at the Ecole polytechnique fédérale de Lausanne, who helped lead the research, said at the press conference.

Jocelyne Bloch, a neuroscientist at the University of Lausanne who placed the implant in Mr Oskam, added: “It was kind of science fiction at first for me, but it has become reality today.”

There have been a number of technological advances in the treatment of spinal cord injury over the past few decades. In 2016, a group of scientists led by Dr. Courtine successfully restored the ability to walk in paralyzed monkeys, and another helped a man regain control of his crippled hand. In 2018, another group of scientists, also led by Dr. Courtine, developed a way to stimulate the brain with electrical impulse generators, enabling partially paralyzed people to walk and cycle again. Last year, more advanced brain stimulation procedures allowed paralyzed subjects to swim, walk and cycle in a single day of treatment.

Mr Oskam had undergone stimulation procedures in previous years and had even regained some ability to walk, but his improvement eventually leveled off. At the press conference, Oskam said these stimulation technologies left him feeling like there was something alien about locomotion, an alien distance between his mind and body.

The new interface changed that, he said, “The stimulation used to control me, and now I control the stimulation.”

In the new study, the brain-spine interface, as the researchers called it, took advantage of an artificial intelligence thought decoder to read Mr Oskam’s intentions – detectable as electrical signals in his brain – and match them to muscle movements. The etiology of natural movement, from thought to intention to action, has been preserved. The only addition, as Dr. Courtine described it, was the digital bridge spanning the injured parts of the spine.

Andrew Jackson, a neuroscientist at Newcastle University who was not involved in the study, said: “This raises some interesting questions about autonomy and the source of commands. You keep blurring the philosophical line between what is brain and what is technology.

Dr Jackson added that scientists in the field had theorized about connecting the brain to spinal cord stimulators for decades, but this was the first time they had had such success in a human patient. “It’s easy to say, it’s much harder to do,” he said.

To achieve this result, the researchers first implanted electrodes in Mr. Oskam’s skull and spine. The team then used a machine learning program to observe which parts of the brain lit up as it tried to move different parts of its body. This thought decoder was able to associate the activity of certain electrodes with particular intentions: one pattern lit up whenever Mr. Oskam tried to move his ankles, another when he tried to move his hips.

Then the researchers used another algorithm to connect the brain implant to the spinal implant, which was configured to send electrical signals to different parts of his body, causing movement. The algorithm was able to account for slight variations in the direction and speed of each muscle contraction and relaxation. And, because signals between the brain and spine were sent every 300 milliseconds, Oskam could quickly adjust his strategy based on what worked and what didn’t. During the first treatment session, he could twist his hip muscles.

Over the next few months, the researchers refined the brain-spine interface to better adapt to basic actions like walking and standing. Mr. Oskam acquired a fairly healthy-looking gait and was able to climb steps and ramps with relative ease, even after months without treatment. Additionally, after a year of treatment, he began to notice marked improvements in his movements without the help of the brain-spine interface. The researchers documented these improvements in weight-bearing, balance and gait tests.

Now Mr Oskam can walk in his house in a limited way, get in and out of a car and stand in a bar for a drink. For the first time, he says, he feels like he’s in control.

The researchers acknowledged the limitations of their work. Subtle intentions in the brain are difficult to distinguish, and while the current brain-spine interface is suitable for walking, the same probably cannot be said for restoring upper body movement. The treatment is also invasive, requiring multiple surgeries and hours of physical therapy. The current system does not resolve all paralysis of the spinal cord.

But the team hoped further advances would make the treatment more accessible and more consistently effective. “It’s our real goal,” Dr. Courtine said, “to make this technology available worldwide to all patients who need it.”