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 disease (PD) has enjoyed renewed popularity. However, the optimal surgical technique, lesion location, and long-term effectiveness of pallidotomy remain subjects of debate, in this article the authors describe their surgical technique 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 validated clinical rating scales and magnetic resonance (MR) imaging of the brain, individuals with severe treatment-refractory idiopathic PD who were believed to be good candidates for surgery underwent computerized tomography scanning- and MR imaging-guided stereotactic pallidotomy. Intraoperative macrostimulation was used to optimize lesion placement and to avoid injury to nearby 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, 12, and 24 months after surgery. Seventy-five patients (mean age 61 years, range 38-79 years) underwent unilateral pallidotomy. Significant improvements were observed in the "off" period scores for the activities of daily living portion of the Unified Parkinson's Disease Rating Scale (UPDRS), the UPDRS motor scores, total "on" time, levodopa-induced dyskinesias, and contralateral tremor. These improvements were maintained 24 months postoperatively. The mean lesion volume measured on the immediate postoperative MR image was 73 +/- 5.4 mm(3). Radiological analysis suggests that initial lesion volume does not predict outcome. The 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 refractory PD.