June 20, 2012
Michael Schulder, MD
In the study, 159 people with Parkinson’s disease were randomly assigned to deep brain stimulation in either the lobus pallidus interna (GPi) region of the brain or the subthalamic nucleus (STN) region of the brain and were followed for three years. Participants reported motor symptoms in a diary for 30 minutes every half hour for two days before each of the six study visits. Medication use was allowed in the study.
The most consistent improvement was related to the effects on movement, including decreased tremor, stiffness and slowness of movement. DBS of both areas of the brain improved motor symptoms by 32 percent on average over the course of three years. As such, this randomized study confirms what previous single-center reports have stated in that patients who have DBS surgery for Parkinson’s disease maintain the benefits of this treatment for years.
However, one provocative finding in this study was that patients with DBS of the STN area of the brain were more likely to have decreased mental function over time compared to those who received DBS of the GPi area of the brain. While it is unclear if this difference was due to different medication doses or the direct effect of DBS in each brain area, further study to clarify this finding is surely needed.