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Spinal Stimulator’s Gentle Zaps Help Treat Parkinson’s

Marc Gauthier was 36 years old when he was diagnosed with Parkinson’s disease. At the age of 44, Marc, who lives in Pessac, France, was treated with a deep brain stimulator device that helps to control tremors in his arms. As he grew older, the disease made it difficult for Marc to walk, causing him to lose balance and fall up to five or six times a day.

In 2021, at the age of 61, Marc underwent an experimental medical procedure that has given him back his mobility. Scientists and doctors with the NeuroRestore group at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland have surgically implanted an array of epidural electrodes within Marc’s vertebrae. These electrodes can stimulate neurons in Marc’s spine in a way that enables his nerves and muscles that control his gait and balance to function more like they did before he developed Parksinon’s. The team documented the procedure in a paper published 6 November in the journal Nature Medicine.

Parkinson’s disease is a neurological disorder characterized by the progressive loss of motor control. While the disease develops differently in every individual, Parkinson’s generally leads to a nervous-system-wide inability to produce the neurotransmitter dopamine and a loss of the neurons that transmit it. These dopaminergic neurons are necessary for many brain functions, including fine motor control. As these neurons are lost, Parkinson’s patients develop the tremors commonly associated with the disease.

“You’re taking advantage of the circuitry of the spinal cord. The spinal cord is doing it for you.” —Eduardo Moraud, NeuroRestore

To counteract these tremors, the research team at EPFL developed a novel intervention: targeted electrical stimulation to the patient’s spine. The researchers had previously seen success using the same stimulator system for spinal injury patients. The team found that in primate models of Parkinson’s, tuned patterns of electrical stimulation applied to the spinal cord could restore a smooth and steady gait to primates with impaired mobility. The team then sought to translate these results to a clinical treatment, and found a willing participant in Marc through their connections to the Lausanne and Bourdeaux medical community. “He was never scared,” says researcher and NeuroRestore group member Eduardo Moraud. “He was very courageous in that sense.”

The technology works by electrically stimulating structures on the spine called dorsal root ganglia, where sensory nerves return to the spine from the body’s extremities. Normally, the dorsal roots coordinate the delicate balance of muscles required for smooth, easy walking. By stimulating the neurons in the dorsal ganglia, the epidural stimulator gets those reflex-driven circuits working as they were before the onset of Parkinson’s disease. “You’re taking advantage of the circuitry of the spinal cord,” says Moraud. “The spinal cord is doing it for you.”

The stimulator array—a pad of electrodes arranged in two columns—was surgically inserted alongside the back of Marc’s spinal cord. The array was positioned to specifically stimulate the dorsal ganglia that most directly controlled Marc’s gait. Once inserted between the vertebrae and the spinal cord, the stimulator was fastened to nearby vertebrae to keep it in place.

After surgical implantation and months of physical rehabilitation, Marc has recovered his ability to walk in a smooth, controlled manner. The device is capable of delivering different stimulation patterns, depending on the situation. The standard pattern is a constant stimulation to compensate for Marc’s baseline imbalances. While this baseline stimulation is enough to keep Marc walking at an easy pace, the stimulator system can drive more effortful leg motions—climbing stairs, getting up from chairs, or walking on uneven terrain—with a supplementary stimulation pattern driven by signals collected from a set of sensors placed on Marc’s feet and legs that measure his intended motions.

Speaking through a translator at a recent press conference, Marc stated, “I experienced a first rebirth twenty years ago when I received a deep-brain stimulation implant. I then experienced a second rebirth two years ago when I received the spinal stimulator. I can now walk with much more confidence and my daily life has profoundly improved.”

With support from the Michael J. Fox Foundation for Parkinson’s Research and the medical device developer Onward, the research team at EPFL hopes to repeat the treatment in six more patients, beginning early next year.

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