An update of the impact of deep brain stimulation on non motor symptoms in Parkinson's disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established therapy for patients with Parkinson's disease (PD), especially those with advanced motor complications. The effect of STN DBS on non motor symptoms (NMS) of PD is less well studied. In this article, we review the pertinent literature on the impact of STN DBS on NMS when they co-exist with disabling motor symptoms in PD patients. We also present evidence that the number and the severity of most NMS decrease after STN DBS which can have a major impact on patients' quality of life.