Figure 1.

Mobility and motor function pre- and post-deep brain stimulation. In advanced Parkinson's disease (A) the duration of response after a single dose of levodopa becomes progressively shorter, thus it becomes increasingly difficult to maintain a satisfactory ON state, with OFF periods (purple bar) and dyskinesia often predominating. While most patients continue to take medication after surgery, the goal following DBS (B) is a reduction in the duration and severity of OFF time, more consistent and longer ON time, as well as an improvement in dyskinesia. Advances in sensing and stimulating technologies promise to enhance DBS delivery, further reducing variability in motor function and improving clinical efficacy. Adapted from Deuschl and Agid (2013).