Acute and chronic effects of anteromedial globus pallidus stimulation in Parkinson’s disease

OBJECTIVE To evaluate the effects of acute and chronic stimulation in the anteromedial part of the globus pallidus internus (GPi) on the symptoms of patients with Parkinson’s disease. METHODS Six patients with severe Parkinson’s disease (Hoehn and Yahr stage 4–5 in “off” drug condition) with motor fluctuations and levodopa induced dyskinesia (LID) were operated on. Chronic electrodes were implanted in the anteromedial GPi bilaterally in five patients and unilaterally in one patient. The effect of stimulation via the four contacts for each electrode (n=11) was assessed postoperatively on the contralateral parkinsonian signs in the off condition and on the contralateral and ipsilateral LID in the “on” condition. The core assessement program for intracerebral transplantation protocol was performed before surgery and then 1, 3, and 6 months after surgery in on and off conditions and in on and off stimulation conditions. RESULTS Stimulation performed postoperatively showed a significant improvement (p