Deep-Brain Stimulation Eases Movement Disorder

Dystonia affects over 300,000 people across North America, experts say

WEDNESDAY, Nov. 8, 2006 (HealthDay News) -- Deep-brain stimulation appears to be effective in treating patients with the movement disorder called dystonia, even when those patients no longer respond to medication.

Dystonia is a neurological disorder characterized by involuntary muscle contractions that result in repetitive movements, twisting and abnormal postures. According to the Mayo Clinic, the condition affects some 300,000 people across North America.

Deep-brain stimulation, formally called bilateral pallidal neurostimulation, "is a reasonable treatment for people who have failed other therapies," concluded study co-researcher Dr. Guenther Deuschl, professor of neurology and chairman of the department of neurology at Christian-Albrechts University in Kiel, Germany.

The procedure, which involves placing a thin wire that can carry electrical currents deep within the brain, is already practiced in various locations.

"This is not a novel treatment, but this is the most thorough clinical trial so far," added Jan Teller, science officer for the Dystonia Medical Research Foundation in Chicago. "This proved beyond doubt that deep brain stimulation is actually a very effective treatment."

The findings are in the Nov. 9 New England Journal of Medicine. The trial was partially funded by an unrestricted grant from Medtronic, which makes the device used to deliver the stimulation.

"Dystonia covers a broad scale of symptoms. You can have dystonia, which is something that [just] bothers you, but people who have the most severe forms are really essentially bedridden," Teller said. "In such cases, no drugs actually help."

Deep brain stimulation has already had some success in treating Parkinson's disease and depression.

"We wanted to know whether deep brain stimulation for dystonia is an adequate procedure or not," Deuschl said.

In the study, 40 patients with primary segmental or generalized dystonia (affecting all or most of the body) were randomly assigned to receive neurostimulation or sham stimulation for three months.

During a six-hour operation, participants received a device connected with a stimulator that was implanted below the skin. Half the patients received actual stimulation; the other half did not.

Once this phase of the trial was completed, all patients were moved to the neurostimulation arm.

After the first three months, individuals in the neurostimulation group experienced a 39 percent reduction in the severity of their condition according to a standard movement score, a 38 percent reduction in disability, and a 30 percent improvement in physical aspects affecting of their quality of life.

After six months, at which time all participants were receiving neurostimulation, the entire group showed a 46 percent average improvement in movement scores compared to the beginning of the study.

Half the patients had more than a 50 percent reduction in symptoms. According to the researchers, that translated into gains across all activities of daily living that boosted both physical and mental quality of life.

"It simply shows that patients with generalized and segmental dystonia do better when they receive stimulation than if they do not," Deuschl said. "A 51 percent reduction in the movement score is a dramatic result when it comes to treatment of dystonia. To have such a degree of improvement is exceptional for other therapeutics."

Participants' mood improved after treatment, and the researchers noted no behavioral abnormalities linked to the therapy. There were some device-related complications such as infections at the stimulator site. These occurred at a rate (18 percent) which was higher than that seen in patients receiving neurostimulation for Parkinson's disease.

"This study provides validation with a very rigorous scientific method of something we already know and are already practicing," noted Dr. Michele Tagliati, associate professor of neurology at Mount Sinai School of Medicine in New York City. "For people who are already doing it, it's obviously strong support of what they're already doing."

More information

For more on dystonia, visit the U.S. National Institute of Neurological Disorders and Stroke.

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