A new way to walk

Two years ago, Marc Gauthier couldn’t walk more than a few feet without freezing or falling, due to his advanced Parkinson’s disease. But the now 63-year-old, who lives near Bordeaux, France, can stroll freely thanks to an experimental spinal cord implant.

A team of doctors at Lausanne University Hospital in Switzerland surgically implanted the novel device. The implant, which sits on the lumbar region of Gauthier’s spinal cord, sends electrical signals that activate his leg muscles. Experts balanced excitement about the novel technology’s potential with some cautions about its usefulness to Parkinson’s patients, but Gauthier applauded its effects. “It changed my life because now I can leave my home, run errands. I even go on foot to exercise,” he told reporters.

The U.S. Food and Drug Administration has approved spinal stimulation to treat chronic pain, but scientists are just now studying its effectiveness for Parkinson’s disease. Parkinson’s is a progressive nervous system disorder in which the cells responsible for making dopamine, a neurotransmitter that helps coordinate the body’s movements, die off. Symptoms include tremors, impaired balance, and slow, rigid movements. Many people with advanced Parkinson’s experience so-called gait “freezing” episodes, in which they are temporarily unable to walk. No currently available therapy effectively treats gait freezing.

Dr. Dennis Turner, professor of neurosurgery, neurobiology, and orthopedic surgery at Duke University School of Medicine, explained that gait freezing is a perception issue. “What people complain about is they’re walking in an open space just fine, but they have to go through a confined space, like a doorway, [then] they hesitate and they stop walking,” he said.

The doctors and scientists who designed and pioneered Gauthier’s treatment with the device reported their findings in a Nov. 6 Nature Medicine study. Lead author Erwan Bezard, a neuroscientist at the French public research institute Inserm, explained in an email how his team designed the device. Noting that most available Parkinson’s therapies target neural circuits directly affected by the loss of dopamine-producing cells, Bezard’s team adopted an alternative strategy of targeting neural circuits in the spinal cord responsible for walking.

“The results were astounding,” said Bezard. He said Gauthier’s freezing episodes almost disappeared, and he fell only 1-2 times a week in comparison to 2-5 times a day prior to receiving the spinal implant.

Turner applauded Bezard and his colleagues for their work on the spinal implant. He described the implant’s ability to trigger stimulation only when needed, as opposed to the stimulation being on at all times, as “really novel.” He compared it to a modern car with an engine that turns off while stopped at an intersection to save energy, then revs up again when the light turns green.

The new device has limited application for Parkinson’s patients because spinal cord stimulation only helps with gait freezing. But deep brain stimulation, an established procedure in which electrodes that can affect brain activity are implanted directly in the brain, can help with many of the other symptoms associated with Parkinson’s. “Spinal cord stimulation will never be a treatment for Parkinson’s as we know it because deep brain stimulation is so good, but it might be an adjunct treatment for this one particular problem, this freezing,” Turner said.

Both spinal cord stimulation and deep brain stimulation only mitigate Parkinson’s symptoms—they can’t cure it. The U.S. Food and Drug Administration approved the first deep brain stimulation therapy for Parkinson’s in 2002.

Turner’s colleague and frequent collaborator, Dr. Nandan Lad, professor of neurosurgery and vice chair for Duke’s NeuroInnovations program, agreed that the new device has limited use for Parkinson’s patients. Lad said it might be applicable to other neurodegenerative diseases in which gait freezing is a dominant symptom. “It’s a step in the right direction, but there’s still a lot of work that needs to be done,” he said.