Brain stimulation study cites ‘rare’ patient side effect
Treatment for Parkinson’s might disrupt swimming abilities in some people
A small study finds that some people lose their ability to swim when their Parkinson’s disease is treated with deep brain stimulation.
Researchers identified nine cases of Parkinson’s patients who effectively forgot how to swim after having a deep brain stimulation device implanted to control symptoms such as tremor, rigidity and slowed movement, according to the report published in Neurology.
“Neurologists and patients should be aware of this potential effect of DBS, even if it’s rare,” said study co-author Dr. Christian Baumann, an associate professor in the department of neurology at the University Hospital of Zurich in Switzerland. It’s not clear how permanent the loss is.
“Turning off DBS improves swimming, as experienced by some patients, but other motor functions get worse so that patients always turn the DBS on again,” said Baumann. “Still, they can learn swimming again, but maybe not at the same level as before.”
The nine patients who lost their ability to swim were among a total of 217 in whom Baumann and his colleagues had implanted DBS devices. The researchers noted all nine had been “proficient swimmers even after their PD diagnosis but found their swimming skills deteriorated after DBS,” and none appeared to have any other physical side effects from the devices.
One was a 69-year-old man who owned a lakeside house and was a proficient swimmer. “(He) literally jumped into the lake where he would have drowned if he had not been rescued by a family member,” the researchers write.
Another case involved a 59-yearold woman who had participated in numerous swimming competitions. But after getting her DBS device, she lost her ability to swim. Through the help of a physiotherapist, she was able to start swimming again, but “never came close to her previous level,” the researchers report. Three patients tried switching off their DBS units. “All found their ability to swim came back immediately,” Baumann and his colleagues write. But because their Parkinson’s symptoms also quickly came back, they decided to turn the devices back on.
Baumann doesn’t know why the DBS affected swimming ability. “That’s unclear,” he said.
“It most probably has to do with the fact that (alteration) of synchronized action in different brain structures impairs some complex motor behaviours.”
Dr. Brian Kopell had never heard of anyone losing their ability to swim after having a DBS implanted. Considering there have been more than 180,000 DBS implantations over 20 years, the new findings are “unusual,” said Kopell, a DBS surgeon and director of the Center for Neuromodulation at the Mount Sinai Health System in New York City.
These researchers “had nearly five per cent who cannot swim anymore,” Kopell said. “I would argue that in 20 years, if it’s really five per cent of the time I think it would have been reported before.”
Kopell worries the new report will alarm patients getting DBS.
“This is potentially a disservice to Parkinson’s patients,” he said.
“It’s a really interesting finding that needs more understanding before anyone can make a clinical recommendation.”