Brain implants that reduce symptoms of Parkinson’s disease could wipe out some people’s ability to swim, warns study
Three of the nine people, who were part of the study, turned off their deep brain stimulation devices and were immediately able to swim. Since their other symptoms worsened, they switched on their deep brain stimulation devices again.
A 59-year-old woman, who was a competitive swimmer and continued to swim after being diagnosed with Parkinson's Disease (PD), was no longer able to do so after a deep brain stimulation device was implanted to control symptoms of the disease. Even after practice, she never regained her former ability level. And she is not the only one who has suffered from a potentially serious side effect of implants meant to control symptoms of Parkinson’s disease.
Nine patients have been identified by researchers, who lost their ability to swim after getting an electronic brain implant to manage tremors and other symptoms of Parkinson’s disease.
According to the research team from the University of Zurich, all nine people had been good swimmers even after they were diagnosed with Parkinson's disease. However, once they had deep brain stimulation (DBS) surgery, researchers found while other movement symptoms improved, their swimming skills deteriorated. The researchers say that the nine people were frustrated by their lost ability to coordinate limb movements for swimming, be it for breaststroke, backstroke, or crawl.
Three of the nine people turned off their deep brain stimulation devices and were immediately able to swim. However, because their other movement symptoms worsened, they switched on their devices again.
“Three patients tried switching off DBS for swimming. All found their ability to swim came back immediately, with improved coordination of the limbs. However, PD motor symptoms deteriorated rapidly; therefore, all decided to switch stimulation on again as soon as possible,” says the study. As the case studies show good swimmers lose ability when the device is on, the team emphasizes that one should be “beware of swimming” if they use deep brain stimulation for Parkinson's.
“The aim of our study was to raise awareness of a potentially serious side effect. And as we suggested in the paper, it seems worthwhile to assess the ability to swim after deep brain stimulation before going into deep water,” Dr. Daniel Waldvogel from the University of Zurich in Switzerland told MEA WorldWide (MEAWW).
What is deep brain stimulation?
Parkinson's disease is a progressive brain disorder that leads to shaking, stiffness, and difficulty with walking, balance, and coordination, says the National Institute on Aging. According to the Parkinson’s Foundation, deep brain stimulation or DBS surgery was first approved in 1997 to treat Parkinson’s disease tremor, and then in 2002 for the treatment of advanced Parkinson's symptoms. In 2016, DBS surgery was approved for the earlier stages of PD — for people who have had PD for at least four years and have motor symptoms that are not adequately controlled with medicines.
For deep brain stimulation, electrodes are placed in some regions of the brain to control abnormal movements. “Deep brain stimulation is a surgical procedure that involves implanting electrodes in the brain, which deliver electrical impulses that block or change the abnormal activity that causes symptoms,” say Cleveland Clinic experts.
They explain: “The electrical impulses are delivered to a targeted area of the brain responsible for the movement symptoms, also called motor symptoms, caused by Parkinson’s disease. Once activated, the pulse generator sends continuous electrical pulses to the target areas in the brain, modifying the brain circuits in that area of the brain. The deep brain stimulation system operates much the same way as a pacemaker for the heart. In fact, deep brain stimulation is referred to as “the pacemaker for the brain.”
A Parkinson's Foundation study estimates that 930,000 people in the US will be living with the disease by 2020, further increasing to 1.2 million people by 2030.
According to the study, which was published in the journal NPJ, the estimated overall prevalence of Parkinson’s among those 45 years old or older is 572 per 100,000, which translates into 680,000 individuals in the US who are at least 45 years old with Parkinson’s in 2010.
What did the study find?
Of the nine documented cases, the research team highlighted three in the research paper. Each person's movement symptoms improved after deep brain stimulation. However, they lost their ability to swim, according to the analysis published in Neurology, the medical journal of the American Academy of Neurology.
This includes a 69-year-old man, a good swimmer who lived on a lake. The man jumped into the water after deep brain stimulation. Since his movement symptoms had improved, he thought he would be able to swim, but he could not. He told researchers he would have drowned if he had not been rescued by a family member.
Another case study involves a 61-year-old woman who swam in competitions crossing Lake Zurich, which is two miles wide. After the surgery, she could barely swim two-tenths of a mile and complained of awkward posture when trying to swim.
The researchers say that the treatment of Parkinson's with DBS has been shown to improve simultaneous task execution, even to a greater extent than movements performed in isolation. Therefore, says the team, the observation that several patients lost their ability to swim was 'unexpected,' mainly because the surgical procedure was considered successful, given the improvement in motor symptoms and quality of life.
"Swimming is a highly coordinated movement that requires complicated arm and leg coordination. Exactly how deep brain stimulation is interfering with this ability needs to be determined,” says Waldvogel. The researchers say more studies are needed in large groups of people to determine the percentage of people with Parkinson's disease who lose their ability to swim with deep brain stimulation, and why exactly it happens.
"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," says Dr. Waldvogel.
The team says even though these reports affected only a few people, they felt this potential risk of drowning was serious enough to alert others with Parkinson's disease, as well as their families and doctor for a carefully supervised assessment of their swimming skills before going into deep water.
“Once awareness is raised, we assume there will be a lot of feedback from other centers confirming our findings. Of course, we don’t quite understand why some patients develop this inability to swim, and we would like to learn more about the pathophysiology, which will require further studies,” Dr. Waldvogel told MEAWW.