His name is Marc and he is 62 years old. He is the first Parkinson’s patient in the world to be able to walk almost normally again. Movements may not seem perfectly natural, but steps are fluid. The sixty-year-old can now go up and down stairs without fear of falling.

And every Sunday, he takes a six-kilometre walk without the slightest difficulty. He owes this veritable renaissance to a neuroprosthesis implanted in his spine by teams of Franco-Swiss neurosurgeons and neuroscientists. These spectacular results have just been published in the journal Nature Medicine.

A dopamine derivative

Prior to the operation, Marc’s condition had deteriorated considerably. Diagnosed in 1996, he had gone through all the characteristic stages of Parkinson’s disease: tremors, movement disorders, muscular rigidity and so on. These symptoms are due to the degeneration, in the brain, of dopaminergic neurons, i.e. those that produce dopamine.

This neurotransmitter plays a fundamental role in movement. Treatment consists of administering a dopamine derivative which greatly improves the patient’s condition. But after decades, the disease progresses more and more unfavorably, and dopamine is no longer sufficient. It is then possible to undertake deep brain stimulation using electrodes implanted directly into the brain.

Here again, the patient’s condition improves markedly. After a few years, however, motor difficulties may reappear, and this time neither dopamine nor brain stimulation are effective. The problems are then those described and experienced by Marc and 90% of people who reach this stage of the disease: “I could hardly walk without frequent falls, several times a day. In certain situations, like getting into an elevator, I’d freeze, as they say.”

Electrical stimulation

The neuroprosthesis implanted in his spine consists of electrodes placed on the spinal cord in the area that controls locomotion. These electrodes send out electrical impulses which stimulate the muscles in a precise way to compensate for Marc’s motor deficits and thus restore walking. This electrical stimulation is programmed and generated by a kind of pacemaker placed in the stomach area.

The trial was conducted in collaboration with Onward Medical, the company responsible for the commercial development of the neuroprosthesis. But the new device now needs to prove itself on a larger number of patients before it can be considered for the market.

A new trial is due to be launched in 2024, this time on six patients. This will be made possible thanks to a $1 million donation from the Michael J. Fox Foundation for Parkinson’s Research, set up by the famous Back to the Future actor, who himself suffers from Parkinson’s disease.