Using implants to electrically stimulate the spinal cord is a clinically approved way to treat chronic pain, and recently scientists have been exploring what these devices could mean for Parkinson’s patients. The authors of a new study have found that the technique can not only reduce pain in these subjects where other treatments have failed, but it also improved motor symptoms in almost three quarters of the patients tested.
Though some mystery remains around exactly how they work, spinal cord stimulators are implantable devices that send electrical pulses into the spinal cord to treat different forms of chronic pain. But so far as Parkinson’s disease is concerned, scientists hope that they might offer a two-in-one solution, reducing pain and improving motor symptoms at the same time.
Parkinson’s disease is characterized by the gradual loss of dopamine-producing neurons, which leads to impaired movement and motor symptoms. These can range from hand tremors to difficulty walking, and while medications and treatments are available to slow the progression of these symptoms, in many cases they fail to produce the desired effect.
Spinal cord stimulation offers a potential pathway forward, as the implants can be programmed to deliver electrical pulses that regulate the signals traveling from the legs to the brain via the spinal cord to improve walking ability. The technique has been investigated through animal studies and in a 2018 paper, in which five Parkinson’s patients all exhibited improved walking and reduced motor symptoms following six months of spinal cord stimulation treatment.
Now a team from the University of California, San Diego, has built on this in a new study involving 15 Parkinson’s patients with an average age of 74, and with an average disease duration of 17 years. All subjects were enduring pain that could not be relieved through other therapies, including drugs and deep brain stimulation, another emerging form of Parkinson’s treatment with great potential.
With the devices implanted near their spines, the subjects chose from continuous electrical stimulation, on-and-off bursts or repeated bursts of varying intensity, which were delivered on an ongoing basis after implantation. The patients were then put through a series of tests to gauge the impacts of the therapy.
All subjects reported a “significant improvement” in pain relief, with an average reduction of 59 percent `across the cohort. In a 10-meter (32-ft) walking test used to assess their mobility and gait, 73 percent of patients showed improvements, at an average of 12 percent.
In a test to assess balance and stability called Timed up and Go, which requires subjects to stand up from a chair, walk three meters (10 ft), return to the chair and sit down, improvements averaging 21 percent were seen in 64 percent of the group.
While the findings are promising, the scientists note it is still early days for the approach and more studies are needed to uncover exactly how it works. One of the immediate questions concerns whether the improved motor symptoms are the result of neurological changes or due to the reduction in pain felt by the subjects.
“We are seeing growing data on novel uses of spinal cord stimulation and specific waveforms on applications outside of chronic pain management, specifically Parkinson’s disease,” says first author of the study Krishnan Chakravarthy. “The potential ease of access and implantation of stimulators in the spinal cord compared to the brain suggests that this is a very exciting area for future exploration.”
The research was published in the journal Bioelectronic Medicine.