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‘Digital bridge’ allows paralyzed patients to walk

Gert-Jan Oskan was paralyzed for nearly 12 years following a bicycle accident. Now he can walk, thanks to a new "digital bridge" that scientists say can reestablish connection between the brain and spinal cord.

(CN) — In a breakthrough study that could represent a quantum leap in the treatment of certain brain and central nervous system injuries, European scientists say they've invented a device that allows a paralyzed patient to stand and walk.

"When there’s a spinal cord injury, the brain is disconnected from the spinal cord, so the communication is interrupted," said the lead researcher on the project, Grégoire Courtine, a a French-born neuroscientist at École Polytechnique Fédérale de Lausanne in Switzerland, during a press call Tuesday. "And what we’ve been able to do here is to reestablish the communication between the brain and the region spinal cord that controls leg movement with a digital bridge."

That so-called "digital bridge" can effectively turn thought into actions — or, as Courtine put it, it can "capture thoughts" and translate them into a stimulation of the spinal cord.

The experimental treatment has been tried just once. Gert-Jan Oskan is a 40-year-old Dutch man who suffered a spinal cord injury in a bicycle accident. For nearly 12 years, he was unable to walk, step or stand. Courtine's team implanted two devices, one into Oskan's brain, and another into his spinal cord. The two devices communicate wirelessly, hence the digital bridge, or as the paper calls it, the "brain-spine interface," or BSI.

Now, Oskan, whom Courtine calls the first "test pilot" of the newly invented system, has regained function in his knees, hips and ankle joints. He can walk — slowly, with the help of crutches — for about 300 to 600 feet. He can stand, with support from his hands, for two to three minutes at a time. He can even climb a few stairs.

Perhaps most remarkably, the treatment appears to work even after the system is shut off.

"The participant regained the ability to walk with crutches overground even when the BSI was switched off," the scientists wrote in their paper, published Wednesday in the journal Nature. "This digital bridge establishes a framework to restore natural control of movement after paralysis."

That's because, Courtine said, the interface "triggers the growth of new nerve connections." He added: "There's probably a convergence between the digital connection and the same type of neurons."

Oskan already had one of the implants — he was the subject of an earlier trial, developed by the same team of researchers. That treatment sent stimulations to his leg, akin to shocks. Patients given that treatment were, with practice, able to walk by a pressing a button, or "clicker," that would send a signal through to their leg. Patients would then have to react to that sudden stimulation. To an observer, their movement appeared almost marionette-like.

"This is radically different," said Courtine. "Gert has full control of the parameter of stimulation. He can stop, walk, climb up staircases. It’s a quite remarkable recovery."

Oskan said that the previous treatment "wasn’t completely natural. The stimulation before was controlling me, and now I'm controlling the stimulation, by my thoughts."

Gert-Jan Oskan walking with the help of a digital bridge (CHUV / Gilles Weber)

For now, the technology is still large and cumbersome. Oskan must wear a backpack and large headset that's connected to a computer, which is monitored by a lab technician.

"Our goal is to reduce the size of the system, for it to be portable for daily use," said Courtine. "The technology is still in its infancy. The important next step is to miniaturize it."

Courtine and his believe their digital bridge can be used to treat a number of different injuries to the brain and central nervous system.

"Paralysis is just the tip of the iceberg," he said. "We're tapping into very specific neurons. Because we have this understanding, we can start targeting other brain function." The team is already looking at using its system to treat stroke patients, patients who have lost their ability to control their bladder, and patients with spinal cord injuries affecting their upper body.

The team also hopes the treatment will be even more successful when the treatment is applied to patients shortly after their injury.

"Imagine when we apply a few weeks after the injury," Courtine said. "The potential for recovery is tremendous."

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