Update on deep brain stimulation for Parkinson's disease.

Deep brain stimulation (DBS) has evolved from an experimental procedure to a major treatment option for Parkinson's disease (PD). Although its underlying mechanism is still not fully understood, a growing body of evidence supports the role of DBS as an effective treatment option for carefully selected patients. Over time, the ever-expanding DBS patient cohort has also revealed the risks and challenges of the surgery. Major goals of this approach include identifying and reaching the correct target of stimulation, as well as delivering electrical current to the appropriate location in an appropriate manner. The safety concerns and adverse outcomes continue to be addressed with ever-improving operative strategies. Imminent developments in biomedical engineering hold the promise of more sophisticated and intelligent DBS devices, and improved imaging technology is providing unprecedented anatomical and functional resolution. Further advances in our understanding of physiology and pathology of the deep brain structures--guided not in small part by experience and access gained with DBS surgery in PD--will shape the future of this field.