Deep brain stimulation with electrical impulses delivered to structures deep within the brain is being intensively investigated for the management of advanced Parkinson disease, according to background information in the article. Although a number of studies have shown that stimulation of two different areas of the brain, the globus pallidus interna (GPi) and the subthalmic nucleus (STN), can be achieved safely and effectively, STN has been thought to be the preferred target. At the same time, the authors note, there does seem to be some evidence that the STN is more vulnerable during surgery and that STN patients may have more postoperative problems.
Valerie C. Anderson, Ph.D., of the Oregon Health and Science University, Portland, and colleagues compared 23 patients with Parkinson disease and problems with medication-induced uncontrolled movement who were randomly assigned to implantation of deep brain stimulators in either the GPi or the STN areas of the brain. Patients' Parkinson symptoms were evaluated with and without medication using a standard rating scale at three, six and 12 months after surgery.
"Off-medication Unified Parkinson's Disease Rating Scale motor scores were improved after 12 months of both GPi and STN stimulation (39 vs 48 percent)," the authors write. "Bradykinesia [extremely slow movement] tended to improve more with STN than GPi stimulation. No improvement in on-medication function was observed in either group. Levodopa [Parkinson medication] dose was reduced by 38 percent in STN stimulation patients compared with three percent in GPi stimulation patients. Dyskinesia was reduced by stimulation at both GPi and STN ( 89 v 62 percent). Cogn
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