Gauthier's Success Suggests a New Way to Tackle Movement Disorders Originating in the Brain

Saturday - November 18 2023, 02:33 UTC - 1 year ago

Marc Gauthier, a mid-30s man diagnosed with Parkinson's disease, struggled to walk without freezing despite using the standard treatments. In 2021, he was part of an experimental trial that implanted a small device in his spinal cord to directly activate the nerves connecting his spinal cord and leg muscles, allowing him to walk confidently. This suggests a new way of tackling movement disorders originating in the brain and has potentially been a great success.

In his mid-30s, Marc Gauthier noticed a creeping stiffness in his muscles. His hand shook when trying to hold steady. He struggled to maintain his balance while walking.

Then he began to freeze in place. When strolling down narrow streets running errands, his muscles seemed to suddenly disconnect from his brain. He couldn’t take a next step.

Gauthier has Parkinson’s disease. The debilitating brain disorder gradually destroys a type of brain cell related to the planning of movement. Since the 1980s, scientists have explored multiple treatments: transplanting stem cells to replace dying brain cells, using medications to counteract symptoms, and deep brain stimulation—the use of an electrical brain implant to directly zap the brain regions that coordinate movement.

While beneficial to many people, such treatments didn’t completely help Gauthier. Even with a deep brain stimulation device and medications, he struggled to walk without freezing in place.

In 2021, he signed up for a highly experimental trial. He had a small implant inserted into his spinal cord to directly activate nerves connecting his spinal cord and leg muscles. While extensively tested in non-human primates with symptoms resembling Parkinson’s, the therapy had never been tried in humans before.

Once Gauthier adapted to the implant, he found he could stroll the banks of Lake Geneva in Switzerland without any aid after three decades living with the disease.

"I can now walk with much more confidence," he said in a press conference. Two years after the implant, "I’m not even afraid of stairs anymore." .

Gauthier’s success suggests a new way of tackling movement disorders originating in the brain. The implant mimics the natural signal patterns the brain sends to muscles to control walking, overriding his faulty biological signals.

"There are no therapies to address the severe gait problems that occur at a later stage of Parkinson’s, so it’s impressive to see him walking," said study author Dr. Jocelyne Bloch to Nature.

The work is an "impressive tour-de-force," said Drs. Aviv Mizrahi-Kliger and Karunesh Ganguly at the University of California, San Francisco, who were not involved in the study.

An Old Conundrum .

It’s easy to take our movement for granted. A skip across a puddle seems mundane. But for people with Parkinson’s disease, it’s a hefty challenge.

We don’t yet fully understand what triggers the disease. A number of genes have been implicated. What’s clear is that the disorder slowly robs a person of the ability to move their muscles as the associated neurons are damaged. These cells pump out dopamine—a brain chemical that’s often linked to unexpected "happy" signals, such as after a surprisingly good meal. However, dopamine has a second job: It’s a traffic controller for muscle movement.

These signals break down in Parkinson’s disease.

One way to treat Parkinson’s is to increase dopamine levels with a drug called levodopa. Deep brain stimulation is another. Here, researchers insert an electrical probe deep inside the brain (hence the name) to activate neural circuits that release dopamine. While effective, the procedure is damaging to sift through the brain to get to the implant’s targeted area.