Deep brain stimulation is a surgical procedure done in “intermediate” stages of Parkinson's Disease when medical therapy alone fails to control the patient’s symptoms adequately.
It is done in patients with “motor fluctuations” with or without “dyskinesias” who require frequent doses of medications to control their symptoms (each dose gives benefit for only a short time) and the medication doses result in abnormal excessive movements (dyskinesias).
DBS is done typically in patients in whom there is good improvement (which may be accompanied by dyskinesias) of symptoms with medications, but the improvement lasts only for a limited period with each dose.
In very advanced stages of Parkinson's Disease, the patients start experiencing symptoms which improve only poorly (eg: imbalance and falls, “freezing” of gait, disturbances of speech) or not at all (eg: memory and intellectual decline) with levodopa and other medications. Such patients are unlikely to have any useful overall improvement of their status with DBS.
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What are the beneficial effects of doing DBS? Dr. Sujit Jagtap