Some Parkinson's patients who have a deep brain stimulation device implanted to control their symptoms have reported an odd side effect -- they lost the ability to swim.
Researchers report on the cases of nine patients who were still good swimmers even after they were diagnosed with Parkinson's disease. After they had deep brain stimulation surgery, their Parkinson's symptoms improved, but they lost their swimming skills.
One patient was a 69-year-old man who'd been a good swimmer and only found out he could no longer swim when he jumped into a lake. He said he would have drowned if he hadn't been rescued by a family member.
Three of the nine patients were able to swim again after they turned off their deep brain stimulation devices. However, they turned them on again because their Parkinson's symptoms worsened.
The study was published online Nov. 27 in the journal Neurology.
"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," said study author Dr. Daniel Waldvogel, from the University of Zurich in Switzerland.
Parkinson's is a progressive nervous system disorder that can result in tremors or movement problems. Deep brain stimulation involves placing electrodes in specific areas of the brain to control abnormal movements. The electrodes are connected to a device -- placed under the skin in the upper chest -- that controls the electrical impulses.
"Swimming is a highly coordinated movement that requires complicated arm and leg coordination," Waldvogel explained in a journal news release. "Exactly how deep brain stimulation is interfering with this ability needs to be determined."
He noted that the study reports on only a few cases and said further research is needed in a large number of patients to pinpoint the percentage who lose their ability to swim due to deep brain stimulation.
"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," Waldvogel said.
The U.S. National Institute of Neurological Disorders and Stroke has more on deep brain stimulation.
PUKmedia \ U.S. News & World Report