Failure of long-term pallidal stimulation corrected by subthalamic stimulation in PD.

Bilateral high-frequency continuous stimulation of the internal globus pallidus or subthalamic nucleus constitutes a new therapeutic approach for the treatment of patients with severe PD. The authors report two patients in whom stimulation of the globus pallidus failed to give long-term relief and was successfully replaced by bilateral subthalamic stimulation. The results emphasize the reversibility of deep brain stimulation therapy and suggest that the subthalamic target is preferable to the pallidal target.

Subthalamic stimulation in Parkinson disease: a multidisciplinary approach.

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.