The conditions that most commonly respond to DBS are motor fluctuations and dyskinesias that are often seen after several years of medical management. Motor fluctuations are often described as “turning on” and “turning off” many times a day as medication levels fluctuate. Dyskinesias are involuntary movements that are often described as “writhing” or “squirming” movements. DBS is effective in reducing “off time” and “on time“ with dyskinesias, while extending good functional state “on time” without dyskinesias. DBS also allows patients to reduce the amount of medication they are taking, which is helpful for patients that have side effects from medications, and to decrease the frequency of medication intake, that by itself can improve quality of life. Another indication for DBS in PD is medication- resistant tremor: in some cases parkinsonian tremor does not completely respond to pharmacological treatment and remains disabling despite appropriate medications. This kind of tremor usually does improve with DBS significantly.

It is important to understand that DBS is not successful in treating all symptoms of PD. It is a proven and effective treatment for motor problems, caused by PD – slowness, muscle stiffness, tremor, etc. Most non-motor symptoms of the disease, including cognitive decline, mood and behavior problems etc.., would not be expected to respond to DBS. In addition, balance problems and freezing of gait do not always improve with DBS.