Background: Deep brain stimulation (DBS) of the globus pallidus interna (GPi) and subthalamic nucleus (STN) has been reported to relieve motor symptoms and levodopa-induced dyskinesia in patients with advanced Parkinson disease (PD). Although it has been suggested that stimulation of the STN may be superior to stimulation of the GPi, comparative trials are limited. Objective: To extend our randomized, blinded pilot comparison of the safety and efficacy of STN and GPi stimulation in patients with advanced PD. Design: This study represents the combined results from our previously published, randomized, blinded, parallelgroup pilot study and additional patients enrolled in our single-center extension study.

Pallidal and STN stimulation appears to be safe and efficacious for the management of advanced PD. A larger study is needed to investigate further the differences in symptom response and the interaction of L-dopa with stimulation at either site.

Bilateral pallidal DBS is safe and efficient in patients who have levodopa-responsive parkinsonism with severe fluctuations. Major improvements in motor score, ADL score, and off time persisted beyond 2 years after the operation, but signs of decreased efficacy started to be seen after 12 months.

The following findings are reported: 1) bilateral thalamic DBS and stimulation contralateral to thalamotomy are safe; 2) staging the procedure does not reduce the risk of dysarthria or gait disequilibrium; and 3) head and voice tremor are primary indications for bilateral DBS.