Researchers are reporting a strange, unexpected side effect that some Parkinson’s Disease patients are experiencing after having a deep-brain-stimulation device implanted. A small number of patients say that, after using the device to treat their Parkinson’s symptoms, they’ve lost the ability to swim. Researchers don’t yet know what’s causing the effect, but until they find out, they’re cautioning Parkinson’s patients to avoid deep water if they’re using a deep-brain-stimulation device.
An Ability Lost
A report in the journal Neurology tells the stories of nine Parkinson’s patients who seem to have lost the ability to swim. All of them had been able to swim despite their Parkinson’s symptoms, but after they began using a deep-brain-stimulation device, they were no longer able to swim. One of the patients was not aware that he couldn’t swim until he jumped into a lake and nearly drowned.
Three of the nine patients said that they regained their ability to swim after they turned off their deep-brain-stimulation device. However, their Parkinson’s symptoms returned when they did, so they turned their devices back on.
“Swimming is a highly coordinated movement that requires a complicated arm and leg coordination,” said one of the report’s authors, Dr. Daniel Waldvogel of the University of Zurich in Switzerland. “Exactly how deep brain stimulation is interfering with this ability needs to be determined.”
What is Deep Brain Stimulation?
Deep brain stimulation (DBS) involves using electrodes to deliver electrical pulses directly to the brain. The electrodes are connected to a device that’s implanted under the skin of the chest, and the device controls the pattern of the pulses in much the same way that a pacemaker delivers electrical pulses to the heart.
In the treatment of Parkinson’s disease, DBS is used to deliver pulses to the parts of the brain that control motor function. The DBS pulses interfere with abnormal brain activity caused by Parkinson’s. In many cases, symptoms such as tremors, stiffness, cramping, and difficulties with walking and balance can be brought under control.
A Cause for Caution
The report’s authors point out that only a small number of patients are reporting this unexpected difficulty. Many Parkinson’s sufferers who are able to swim before having a DBS device implanted continue to be able to do so even after they begin using the device. Yet, Waldvogel felt that it was important to make the effect known.
“Even though these reports affected only a few people, we felt this potential risk was serious enough to alert others with Parkinson’s disease, as well as their families and doctors,” he says.
While the effect is being investigated, there is a reason for DBS users to be careful.
“Until more research is done to determine why some people with deep brain stimulation can no longer swim, it is crucial that people be told now of the potential risk of drowning and the need for a carefully supervised assessment of their swimming skills before going into deep water,” Waldvogel says.