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Brain Stimulation Benefit for Parkinson's Lasts

The technique of deep brain stimulation has benefited some people with Parkinson's disease, but how long the effect lasts has not been known since it is a relatively new procedure.

Now, a French research team reports in this week's New England Journal of Medicine that improved muscle control is maintained for at least 5 years in patients with advanced Parkinson's disease treated with bilateral stimulation of the subthalamic nucleus.

However, another group reported this week at a medical meeting that relatively minor cognitive impairment can occur during stimulation.

In the French study, Dr. Paul Krack and associates at Joseph Fourier University in Grenoble followed 49 patients, ages 34 to 68 years, who had the brain stimulator implanted between 1993 and 1997.

At 5 years, tremor had improved by 75 percent and muscle rigidity by 71 percent when the patients were not taking their medication. The average dose of levodopa medications they needed to take decreased by more than half.

Most subjects were independent in their activities of daily living, the report indicates, even though they had all required the services of a caregiver prior to the surgery.

However, the disease continued to progress: three patients became demented, five developed drug-resistant apathy, and three died.

Those most likely to benefit from deep brain stimulation are "younger patients who are very disabled by features of Parkinson's disease and who respond to drugs, but in an unpredictable manner," Dr. Anthony E. Lang told Reuters Health. Lang, at the University of Toronto, is the author of an accompanying editorial.

Meanwhile, Dr. Tamara Hershey at the meeting of the Society for Neuroscience in New Orleans presented research results for her team at Washington University School of Medicine in St. Louis.

Hershey noted that mental processes of patients with brain implants are better when stimulators are turned off than when they are on. For example, a test administered to 24 patients showed decreased working memory performance under a high memory load condition.

"There's no denying that deep brain stimulation has a huge impact on quality of life," Dr. Hershey told Reuters Health. The cognitive changes they observed are "relatively minor," so it is likely that "no patient would want to return to the impaired motor state" in exchange for better cognitive function.

But "perhaps the frequency or rate of stimulation could be tweaked a little bit for those who seem to not be thinking as clearly," she added.

Commenting on these findings, Lang said: "Patients should definitely not try to alter their stimulators, but if this type of research can be confirmed, and we do find there are certain cognitive effects of having the stimulator turned on, then trying to manipulate the stimulator parameters does make sense."

SOURCE: The New England Journal of Medicine, November 13, 2003. Reference: The New England Journal of Medicine Volume 349 - November 13, 2003 - Number 20 Table of Contents

Subthalamic Stimulation for Parkinson's Disease - Living Better Electrically? A. E. Lang

Five-Year Follow-up of Bilateral Stimulation of the Subthalamic Nucleus in Advanced Parkinson's Disease P. Krack and Others

The New England Journal of Medicine The Parkinson's Disease collection covers topics such as deep-brain stimulation, dopamine agonists, and pallidotomy and includes research articles, case reports, reviews, and editorial commentary. (17 Articles)

Source Date: Nov 13 2003
Source Publication: Reuters Health
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