Deep brain stimulation surgery for Parkinson's disease: mechanisms and consequences.

Despite the introduction of new medications, motor fluctuations and dyskinesias disable a significant proportion of Parkinson's disease patients. This has lead to renewed interest in stereotactic neurosurgery. A skilled team is needed to ensure that patient assessment and selection, operative technique, intraoperative monitoring, and post-operative management are optimised. High frequency stimulation has similar effects to ablative surgery, and is generally preferred. The clinical effects and possible mechanisms of action of deep brain stimulation of the subthalamic nucleus and globus pallidus are reviewed.