Comparison of pallidal and subthalamic deep brain stimulation for the treatment of levodopa-induced dyskinesias.

Deep brain stimulation (DBS) can relieve dyskinesias effectively and safely. This modality is applied most commonly in the treatment of dyskinesias associated with levodopa therapy for Parkinson disease. The subthalamic nucleus (STN) and globus pallidus internus (GPi) are the most common surgical targets. Deep brain stimulation of the GP has a direct antidyskinetic effect, whereas relief of dyskinesias by DBS of the STN depends on postoperative reduction of dopaminergic medications. Outcomes are similar for DBS in these two sites despite the different mechanisms by which the stimulation relieves dyskinesias. Deep brain stimulation of the STN has become the surgical treatment of choice in many movement disorders programs but this modality has not been compared with DBS of the GPi in randomized controlled trials, and the superiority of one site over the other remains unproven. In the absence of data demonstrating superiority, selection of the stimulation target should be individualized to meet the needs of each patient. Selection of the target should be based on the patient's most disabling symptoms, response to medications (including side effects), and the goals of therapy, with consideration given to the different antidyskinetic effects of DBS of the STN and GPi.