Marc, who has severe Parkinson’s disease, can now walk several kilometres without a cane or helper
CHUV 2022/WEBER Gilles
A man with Parkinson’s disease has experienced a substantial improvement in his ability to walk after being fitted with a device that electrically stimulates his spinal cord. The findings, although based on one person’s experience, suggest this technique could be used widely to treat movement deficits in people with the condition.
Around 90 per cent of people with Parkinson’s experience some kind of movement difficulty, says Grégoire Courtine at the Swiss Federal Insitute of Technology in Lausanne. Existing treatments include drugs that target parts of the brain affected by a loss of the chemical dopamine, which regulates movement, as well as deep-brain stimulation, which similarly focuses on these brain areas and changes some of the abnormal electrical signals that cause symptoms.
However, many people with Parkinson’s disease don’t respond to these treatments, particularly if their condition is advanced, says Courtine. He and his colleagues wanted to find out whether directly stimulating the spinal cord in a person with severe Parkinson’s could alleviate their gait-related problems.
They focused on epidural electrical stimulation (EES), which can modulate the activity of neurons behind locomotor movements. Previous studies showed that the technique can restore standing and walking in people with paralysis following a spinal cord injury.
The team devised a form of EES that specifically targets neurons in the spine that are activated when legs walk, which showed promise in non-human primates with Parkinson’s-like symptoms. To test it in a person, the researchers recruited a 62-year-old man called Marc, who has experienced Parkinson’s symptoms for around 30 years. These included severe motor issues, particularly gait freezing – sudden, short and temporary episodes of an inability to move despite the intention to walk.
For the method to be effective, the researchers had to first map the neurons in Marc’s spine. This helped to guide the implantation of the electrical stimulators so they would only target his legs’ neurons.
They then placed sensors on Marc’s legs and shoes to monitor the electrical activity of the neurons that activate the muscles in these limbs and his feet. When these sensors detected this electrical activity, they activated the stimulators.
After three months of rehabilitative training using the stimulators, Marc more or less stopped experiencing gait freezing, says Courtine. Marc says that passing through narrow paths or turning as he walked had previously caused gait freezing, which led to him falling five or six times a day. Marc has now been using the stimulator for two years and says he hardly falls at all any more, allowing him to walk several kilometres at a time without a cane or helper.
The stimulation is personalised to Marc, who found it particularly difficult to move one leg, says Courtine, prompting the researchers to apply more stimulation to that limb. Nevertheless, they think a similar technique could help many people with severe Parkinson’s.
“In response to the precise stimulation of the lumbar spinal cord, [we’ve] observed for the first time the remarkable improvement of gait deficits due to Parkinson’s disease,” says team member Jocelyne Bloch. “I really believe that these results open realistic perspectives to develop treatments that alleviate gait deficits due to Parkinson’s disease.”
The researchers hope to test this method in more people with the condition, says Bloch. There are at least five more years of development and testing of the technology before the treatment will reach people outside a trial, says Courtine.
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