Deep brain stimulation of the subthalamic nucleus in Parkinson's disease 2003-2013: Where are we another 10 years on?

High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is now ending its second decade as an established modality for treating Parkinson's disease (PD). Knowledge of the pathophysiology of PD and clinical applications for STN DBS is burgeoning. Despite this, the mechanism of how STN DBS works remains an enigma. Furthermore, motor symptoms have been seen as a focus for improved quality of life after STN DBS yet non-motor symptoms also play an integral role in determining treatment outcome. In this paper, new evidence for the mechanisms of action of STN DBS is discussed and the impact of the therapy on motor and non-motor symptoms of PD is analysed. Future directions of treatment and emerging technologies are also reviewed.