WEDNESDAY, Sept. 25, 2001 (HealthDayNews) -- A new study provides the best evidence yet that using implanted electrodes to stimulate the brain can help patients with severe Parkinson's disease when drug treatment is no longer effective.
The deep-brain stimulation treatment improved mobility, stopped uncontrollable writhing movements and reduced the tremor, muscle rigidity and balance problems caused by the disease, reports the Deep-Brain Stimulation for Parkinson's Disease Study Group in the Sept. 27 issue of The New England Journal of Medicine.
The group implanted electrodes in 134 patients with advanced Parkinson's disease at 18 medical centers around the world. All the patients were incapacitated by severe movement problems, despite drug treatment.
Patients had two needle-like electrodes implanted in a brain center that controls movement, either the subthalamic nucleus (STN) or the globus pallidus (GPI). All the patients kept diaries recording their activity, and their motor function was assessed six months after the implants.
Both groups showed improvement in overall function -- a 51 percent improvement for the STN group and 33 percent for the GPI group. The amount of time patients had good mobility increased from 27 percent before the operation to 74 percent afterward for the STN group and from 28 percent to 64 percent for the GPI group.
"This is a very impressive treatment," says Dr. C. Warren Olanow, chairman of the neurology department at Mount Sinai Medical Center in New York City and a leader of the research group. "It is hard to convey in words the amount of improvement that patients show. With this treatment, patients can sometimes function in a normal way that is not possible with medical treatment alone."
The deep brain stimulation system, made by Medtronic, Inc., consists of a battery-operated stimulator worn on the chest, with wires running under the skin of the chest wall up to the implanted electrodes. The signals transmitted through the electrodes calm the disorderly activity of brain cells that causes the symptoms of Parkinson's disease, Olanow says.
The side effects of the implant were "not enormously high," Olanow says. "When you put a needle into the brain of a patient, there is some risk of damage or trauma to the brain. Seven patients had hemorrhages, of which four were clinically significant."
While the brain stimulation system has been approved by government authorities in Europe, the U.S. Food and Drug Administration (FDA) has not yet approved it for Parkinson's disease here. An FDA advisory panel voted unanimously to recommend approval last year, and "we are awaiting FDA approval, which hopefully be forthcoming shortly," Olanow says.
Lack of FDA approval can raise an economic problem, since the system costs about $50,000, he says. But a number of medical centers in this country offer the system, and public financing often is available, says Joseph McGrath, a spokesman for Medtronic.
The FDA approved the system for treatment of uncontrollable tremor not caused by Parkinson's disease in 1997, McGrath says, and "at least 25 medical centers in the United States are offering deep-brain stimulation for Parkinson's disease" by physicians who have obtained an investigational device approval. "More than 14,000 patients worldwide have been treated for either tremor or Parkinson's disease with the deep-brain stimulation system," he says.
As for financing, "at last count 22 states have Medicare coverage of deep-brain stimulation as a treatment for Parkinson's disease," McGrath says.
What To Do
"I would recommend that any Parkinson's patient considering the treatment should go to a local Parkinson's expert and then be referred to a center for evaluation," says Olanow.
Information about Parkinson's and its treatment is available from We Move and the National Institute of Neurological Disorders and Stroke.
