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Deep Brain Stimulation: New Safety Data is In

Clancy, Frank

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Frank Clancy's articles have appeared in American Health, Consumer Reports on Health and Health magazine, among others.

By the harsh standards of Parkinson's disease, Bonnie Stockmo's symptoms were not terrible when she first heard of a then-experimental treatment known as deep brain stimulation (DBS) in the fall of 2001. “I had a tremor in my right hand, and my right leg was giving me a real bad time,” Stockmo remembers. She was 67. She'd had Parkinson's: disease for 10 years – long enough to know that the disease would only grow worse. If she was going to have the surgery, she wanted to do it now.

The Food and Drug Administration (FDA) approved DBS as a treatment for Parkinson's disease in January 2002. A month later, a neurosurgeon at the University of Minnesota drilled through the Eagan, Minn., woman's skull and threaded two insulated leads, or electrodes, deep into her brain. She was on the operating table, anesthetized and immobilized but awake and alert, for nine hours.

Two weeks later, the surgeon implanted two battery-operated devices known as neurostimulators, which are similar to pacemakers, near Stockmo's collarbones. When the stimulators were turned on, sending a steady stream of electricity through the electrodes, the tremors disappeared. She was thrilled.

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Fuller Picture Emerges

Now, more than three years after the FDA approved DBS as a treatment for Parkinson's disease, researchers are still developing a fuller understanding of the procedure's complications, side effects and risks.

At the annual meeting of the American Neurological Association last October, Joseph Jankovic, M.D., a professor of neurology at Baylor College of Medicine and the director of the Parkinson's Disease Center and Movement Disorders Clinic in Houston, Texas, summarized what had happened to the first 187 Parkinson's disease patients who underwent the procedure at his facility. This was the first report to focus on the risks of DBS experienced by a large number of patients.

Indeed, according to the study, complications were common:

* By far the most frequent were caused by the electrical stimulation, and appeared after the neurostimulator was turned on (usually about two weeks after surgery). Complications included speech problems, abnormal coordination or feeling (numbness, tingling, burning sensations) and a weakened voice. Most of those problems were corrected by adjusting the voltage and/or settings of the neurostimulator.

* Seven patients experienced complications during surgery, such as fainting, irregular heartbeat, bleeding or low blood pressure. The most serious surgical complication was a brain hemorrhage. The person recovered.

* Thirty-six instances of complications were related to the device itself, including head or neck pain, a device that malfunctioned and skull fractures. In three cases, electrodes traveled to elsewhere in the body and the person had to undergo additional surgery.

* Roughly one of ten patients experienced post-operative complications such as hallucinations, fever, nausea, headaches and throat inflammation.

In all but a few cases, no additional surgery was needed. No one died as a result of DBS, nor did any suffer complications so severe that the device was removed.

Figure. In DBS, the ...
Figure. In DBS, the ...
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“If patients are appropriately selected for DBS, the procedure itself is safe. The key to overall efficacy and safety is proper selection of patients,” Dr. Jankovic says.

Their general health has to be as good as it does for any patient undergoing a surgical procedure,'' he added.

This study helps give people with Parkinson's disease a realistic view of what to expect from DBS, says Kathleen Shannon, M.D., associate professor of Neurological Sciences at Rush University Medical Center and Rush Medical College in Chicago. “The lay press never talks about complications – never, never, never,” says Dr. Shannon. “They show someone who couldn't walk going down the hall. It's important for people thinking about that option to know that there are definite risks, and they need to be figured into the equation.”

Dr. Shannon, however, cautions against drawing broad conclusions from this report, since both the results and risks of surgery depend heavily on the skill and experience of the surgeon. These patients were “at a cream-of-the-crop center, with a cream-of-the-crop surgeon, a cream-of-the-crop neurologist, and a cream-of-the-crop surgical team. It's very important for patients to realize that these published results are from the best surgeons – the best. That may not be true at their local hospital. They should want to know how many of these procedures their surgeon has done.”

Likewise, DBS requires a highly skilled neurologist, who can help select and locate the proper target in the brain. And adjusting the electricity is often a complicated process. “It's not like surgery is the end of it,” says Dr. Shannon. “It's a team approach.”

“We've been doing this for nine years, and we are still learning,” Dr. Jankovic says.

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Be Realistic

It's crucial that people who choose the procedure meet the appropriate criteria. Those who respond well to DBS were typically diagnosed with Parkinson's disease when they were younger and underwent the procedure ten or 15 years later. They were also the ones whose disease symptoms initially responded the best to medication, Dr. Shannon says.

It's also important to have realistic expectations of what DBS can accomplish. DBS doesn't cure the disease; it doesn't even halt the underlying loss of brain cells. “Patients sometimes have unrealistic expectations, and think surgery is going to make them 20 years younger,” Dr. Jankovic says.

“Unfortunately, it doesn't do that. Most studies, including ours, suggest that we borrow two or three years,” he adds. “We set the patient back the way they were two or three years ago.”

In retrospect, Stockmo realizes that some of her hopes – she thought she might be able to stop her medications – were unrealistic. (She was able to lower her dosage.) Now, three years later, she remains pleased with the results of DBS surgery, even as her Parkinson's disease has, predictably, progressed. “I still have no tremors – none whatsoever,” she says. “I don't know where l'd be right now if I hadn't had deep brain stimulation. I'd probably be in a wheelchair.” This past winter, though, Stockmo found herself losing her balance and falling frequently, especially when she first stood up. Her neurologist increased her medication. Equally important, she learned to make small adjustments: she pauses to gather herself, she says, before trying to move.

And Stockmo remains active. On Mother's Day, she walked and jogged five kilometers to raise money for breast cancer research– The Race for the Cure.

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Resources

American Academy of Neurology Foundation The Brain Matters

www.thebrainmatters.org

National Institute of Neurological Disorders and Stroke (NINDS)

(800) 352-9424 TTY: (301) 468-5981

http://www.ninds.nih.gov/disorders/deep_brain_stimulation/deep_brain_stimulation.htm

MedLine Plus

www.nlm.nih.gov/medlineplus/parkinsonsdisease.html

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For More Information in Patients Pages:

For the article “Surgery for Patients with Parkinson's Disease,” go to the American Academy of Neurology's journal Neurology at www.neurology.org, click on “Patient Pages” and scroll down to January 2004.

©2005 American Academy of Neurology

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