Head to Head: Brain implants are better for Parkinson's patients
Nathan Seppa
People with Parkinson's disease who get electrodes surgically implanted in their brains regain some muscle control and are better able to handle daily activities than patients given medication only, researchers in Germany find.
Scientists first developed the operation, called deep-brain stimulation, in the 1990s. Surgeons implant a small electrode in a brain area that normally serves as a relay station for nerve signals. In Parkinson's patients, particularly after years of medication, this region sends aberrant signals that disrupt nerve circuits and cause limbs to jerk involuntarily. The pulses from the electrode apparently block these abnormal signals.
The surgery has typically been a last resort for people whose condition—marked by tremors, rigidity, and imbalance—has worsened despite medication, says neurosurgeon Robert R. Goodman of Columbia University College of Physicians and Surgeons.
The new study, which appears in the Aug. 31 New England Journal of Medicine, is the first to directly compare medication plus deep-brain stimulation with medication-only treatment among randomly selected patients, says Pablo Martinez-Martin, a neurologist at the Carlos III Institute of Health in Madrid. Moreover, he says, the researchers measured quality of life in the patients, which previous assessments hadn't.
A team led by Günther Deuschl, a neurologist at Christian Albrechts University in Kiel, Germany, randomly assigned 152 patients with Parkinson's disease to get surgery or to continue their medication. The participants were an average of 61 years old and had been treated for Parkinson's disease for roughly 13 years. Patients in each group kept a diary rating their mobility for 3 days before starting the study and for 3 days at the end of the 6-month trial.
One patient in the surgery group died of a cerebral hemorrhage. Overall, the patients who underwent surgery saw their daily times of immobility drop from 6 hours to 2 hours, on average. Also, time in which they were free from troublesome movements jumped from 3 hours a day to nearly 8 hours. They also needed only half as much medication as they had previously taken.
Patients getting only medicine showed no improvement during the same time period.
Parkinson's disease results from a loss of dopamine, which is needed to facilitate nerve signaling that guides movement. Although drugs can replace or mimic dopamine, their effect fades over time.
The surgery has a 2 to 5 percent risk of serious side effects and costs roughly $50,000, says neurologist C. Warren Olanow of the Mount Sinai School of Medicine in New York. Nevertheless, Olanow says, the success rate of the operation is about 80 percent.
A limited number of surgical teams can perform the surgeries and patients require close follow-up, says Martinez-Martin.
On the basis of these new findings, researchers are investigating whether Parkinson's patients might benefit from getting the surgery earlier in the course of the disease, says Deuschl.
Many doctors "have gradually come to the conclusion that [the surgery is] probably more beneficial if we offer it to the patient earlier than we do," Goodman says.
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References:
Deuschl, G., et al. 2006. A randomized trial of deep-brain stimulation for Parkinson's disease. New England Journal of Medicine 355(Aug. 31):896-908. Abstract available at http://content.nejm.org/cgi/content/abstract/355/9/896.
Further Readings:
Brownlee, C. 2005. Inner-brain electrode may curb depression. Science News 167(March 12):174. Available to subscribers at http://www.sciencenews.org/articles/20050312/note14.asp.
The Deep-Brain Stimulation for Parkinson's Disease Study Group. 2001. Deep-brain stimulation of the subthalamic nucleus or the pars interna of the globus pallidus in Parkinson's disease. New England Journal of Medicine 345(Sept. 27):956-963. Available at http://content.nejm.org/cgi/content/full/345/13/956.
Krack, P., et al. 2003. Five-year follow-up of bilateral stimulation of the subthalamic nucleus in advanced Parkinson's disease. New England Journal of Medicine 349(Nov. 13):1925-1934. Available at http://content.nejm.org/cgi/content/full/349/20/1925.
Limousin, P., et al. 1998. Electrical stimulation of the subthalamic nucleus in advanced Parkinson's disease. New England Journal of Medicine 339(Oct. 15):1105-1111. Available at http://content.nejm.org/cgi/content/full/339/16/1105.
For additional information about Parkinson's disease and deep brain stimulation, go to http://www.fda.gov/fdac/features/1998/498_pd.html, and http://www.ninds.nih.gov/disorders/deep_brain_stimulation/.
Sources:
Günther Deuschl
Department of Neurology
Universitätsklinikum Schleswig-Holstein
Campus Kiel
Christian Albrechts University
Schittenhelmstrasse 10
24105 Kiel
Germany
Robert R. Goodman
Department of Neurological Surgery
Columbia University
710 West 168th Street, Room 426
New York, NY 10032
Pablo Martinez-Martin
Unit of Neuroepidemiology
National Centre for Epidemiology
Carlos III Institute of Health
C/. Sinesio Delgado, 6
28029 Madrid
Spain
C. Warren Olanow
Department of Neurology
Mt. Sinai School of Medicine
One Gustave Levy Place
Box 1137
New York, NY 10029
From Science News, Volume 170, No. 10, September 2, 2006, p. 149.
