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 suggesting the technique could be used widely to treat movement deficits in people with the condition.
Around 90% of people with Parkinson’s experience some kind of movement difficulty, said Grégoire Courtine at the Swiss Federal Institute 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, and which similarly focuses on these brain areas and changes some of the abnormal electrical signals that cause symptoms.
However, many people with Parkinson’s don’t respond to these treatments, particularly if their condition is advanced, Courtine said.
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.
New Scientist reports that 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 after a spinal cord injury.
The team devised a form of EES specifically targeting 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, they recruited a 62-year-old man named 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 his 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, said Courtine.
Marc said that passing through narrow paths or turning as he walked had previously caused gait freezing, resulting in him falling five or six times a day.
He has now been using the stimulator for two years and 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, said 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 from Parkinson’s disease,” said team member Jocelyne Bloch.
“I really believe 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, Bloch said.
There are at least five more years of development and testing of the technology before the treatment will reach people outside a trial, Courtine added.
Study details
A spinal cord neuroprosthesis for locomotor deficits due to Parkinson’s disease
Tomislav Milekovic, Eduardo Martin Moraud, G. Courtine, et al.
Published in Nature on 6 November 2023
Abstract
People with late-stage Parkinson’s disease (PD) often suffer from debilitating locomotor deficits that are resistant to currently available therapies. To alleviate these deficits, we developed a neuroprosthesis operating in closed loop that targets the dorsal root entry zones innervating lumbosacral segments to reproduce the natural spatiotemporal activation of the lumbosacral spinal cord during walking. We first developed this neuroprosthesis in a non-human primate model that replicates locomotor deficits due to PD. This neuroprosthesis not only alleviated locomotor deficits but also restored skilled walking in this model. We then implanted the neuroprosthesis in a 62-year-old male with a 30-year history of PD who presented with severe gait impairments and frequent falls that were medically refractory to currently available therapies. We found that the neuroprosthesis interacted synergistically with deep brain stimulation of the subthalamic nucleus and dopaminergic replacement therapies to alleviate asymmetry and promote longer steps, improve balance and reduce freezing of gait. This neuroprosthesis opens new perspectives to reduce the severity of locomotor deficits in people with PD.
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