Subthalamic Stimulation in Parkinson Disease

BACKGROUND: High-frequency stimulation of the subthalamic nucleus constitutes a therapeutic advance for severely disabled patients with Parkinson disease. OBJECTIVE: To evaluate the efficacy and safety of continuous bilateral high-frequency stimulation of the subthalamic nucleus in patients with Parkinson disease. DESIGN: A prospective study of patients with Parkinson disease treated at a university hospital. PATIENTS AND METHODS: Electrodes were implanted bilaterally in the subthalamic nucleus of 23 consecutive patients with Parkinson disease who responded well to levodopa but had severe motor complications. There were 16 men and 7 women (mean +/- SEM age, 53 +/- 2 years) who had a mean +/- SEM disease duration of 14.7 +/- 1.0 years. Targets were determined by 3-dimensional magnetic resonance imaging, combined with intraoperative electrophysiologic recordings and stimulation. RESULTS: Six months after surgery, motor disability, levodopa-induced motor fluctuations, dyskinesias, and the daily dose of levodopa equivalent decreased significantly by 67%, 78%, 77%, and 61%, respectively, compared with the preoperative state. No significant morbidity was observed, except transient depression in 4 patients. CONCLUSIONS: The beneficial effects of subthalamic stimulation depend on (1) the criteria used for patient selection, (2) the precision with which the subthalamic nucleus is targeted (dependent on the 3-dimensional magnetic resonance imaging and the intraoperative electrophysiologic and clinical assessments), and (3) the long-term postoperative adjustment of stimulation variables.