Stereotactic pallidotomy performed without using microelectrode guidance in patients with Parkinson's disease: surgical technique and 2-year results

Object. Pallidotomy for the treatment of medically refractory Parkinson's d isease (PD) has enjoyed renewed popularity. However, the optimal surgical t echnique, lesion location, and long-term effectiveness of pallidotomy remai n subjects of debate, in this article the authors describe their surgical t echnique for performing pallidotomy without using microelectrode guidance, and the clinical and radiological results of this procedure. Methods. Patients were evaluated preoperatively by using a battery of valid ated clinical rating scales and magnetic resonance (MR) imaging of the brai n, individuals with severe treatment-refractory idiopathic PD who were beli eved to be good candidates for surgery underwent computerized tomography sc anning- and MR imaging-guided stereotactic pallidotomy. Intraoperative macr ostimulation was used to optimize lesion placement and to avoid injury to n earby structures. Lesion location and size were calculated from MR imaging sequences of the brain obtained within the first 24 hours after surgery and again 3 months later. Clinical examinations were conducted at 1.5, 3, 6, 1 2, and 24 months after surgery. Seventy-five patients (mean age 61 years, range 38-79 years) underwent unil ateral pallidotomy. Significant improvements were observed in the "off" per iod scores for the activities of daily living portion of the Unified Parkin son's Disease Rating Scale (UPDRS), the UPDRS motor scores, total "on" time , levodopa-induced dyskinesias, and contralateral tremor. These improvement s were maintained 24 months postoperatively. The mean lesion volume measure d on the immediate postoperative MR image was 73 +/- 5.4 mm(3). Radiologica l analysis suggests that initial lesion volume does not predict outcome. Th e only permanent major complication was a single visual field defect. Conclusions. Pallidotomy performed without using microelectrode guidance is a safe and effective treatment for selected patients with medically refrac tory PD.