Deep Brain Stimulation: An Introductionby Ray McIntyre | April 12, 2005
Imagine that your head and neck twitch uncontrollably, or seize up painfully, or that your left arm starts shaking for no reason. Dystonia refers to a group of complex muscle disorders that involve involuntary twisting, repetitive movements that cause abnormal, sometimes painful positions.
Or imagine that your hand shakes so badly that you can’t write your name or pour a liquid without spilling it everywhere. Essential tremor is the rhythmic shaking of a body part, usually a hand or arm, especially when the person tries to do something like hold a pen or cup. People with Parkinson’s disease also have tremors, as well as muscle stiffness and slowness of movement.
A new treatment
What do all these neuromuscular disorders have in common? Typically, people with these conditions are treated with medications, which may or may not give them relief. But a new therapy, called deep brain stimulation (DBS), is demonstrating in research studies that it may provide an excellent way of controlling dystonia and tremors.
A hidden electrical system
Deep brain stimulation involves putting the tip of a hair-thin wire down inside the brain in a special area that controls movement. The wire then runs up through a small hole in the skull and under the scalp down to a little device implanted under the collarbone. The device, called a neurostimulator, sends tiny electrical impulses down the wire into the brain. The person can turn the DBS on when needed, and turn it off during sleep (when tremors are less).
DBS and Parkinson’s
The picture for Parkinson’s disease is very encouraging. In 1997, the U.S. Food and Drug Administration (FDA) approved DBS for the treatment of tremor in Parkinson’s disease using a single implanted electrode. In January 2002 the FDA approved DBS using two implanted electrodes (bilateral, meaning one on each side of the brain).
Over 2,000 people with Parkinson’s disease in the U.S. have had DBS systems implanted. For most people, DBS has relieved many symptoms and improved their ability to walk and do the activities of daily life. Researchers believe that as many as 15% of people with Parkinson’s could benefit from DBS each year. So far, the risks seem acceptable; a study in 2000 reported that long-term use of DBS does not cause damage to the brain around the electrode.
DBS and dystonia
About 100 people around the world with dystonia have had a DBS system implanted. German researchers reported in February 2002 that bilateral DBS relieved head twitching in five patients with cervical dystonia (spasmodic torticollis). This is similar to research results in previous years.
DBS and essential tremor
Given the successes in using DBS to treat the tremors in Parkinson’s disease, researchers have turned to applying DBS to essential tremor. A U.S. study in 1999 evaluated DBS of 38 people with essential head tremor. All of the people had less tremors after the DBS system was implanted. And a Swedish study in January 2002 of 27 people with essential tremor found all had improved ability to do daily activities.
The future for DBS
Researchers are interested in expanding testing of DBS for other disorders. Studies have found DBS can relieve chronic nerve-related pain. In one study, a man given DBS for pain after a stroke also had some improvement in the arm weakened by the stroke. Possible areas of study for DBS are in seizure disorders, multiple sclerosis, paralysis, obsessive-compulsive disorders, and depression. Although the possibilities are exciting, it will no doubt be many years before DBS would be used to treat these additional conditions.
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Kumar, R., Dagher, A., Hutchinson, W.D., Lang, A.E., & Lozano, A.M. (1999). Globus pallidus deep brain stimulation for generalized dystonia: clinical and PET investigation. Neurology, 53(4), 871-874.
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Written by Mary Kugler
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