EFFICACY OF MICROELECTRODE-GUIDED, POSTEROVENTRAL, UNILATERAL AND BILATERAL PALLIDOTOMY IN THE TREATMENT OF PARKINSON′S DISEASE

Objective: To investigate the short- and long-term efficacy of microelectrode-guided, posteroventral pallidotomy (PVP) in a large cohort of patients with advanced Parkinson's disease (PD). Background.: Advances in motor physiology, neuroimaging and neurosurgery have led to increased use of unilateral and bilateral PVP to treat patients with PD, particularly those with severe, medically intractable disease. Results from a prospective follow-up of a large series of patients are needed to establish the long-term efficacy and safety of PVP. Methods: We followed 101 consecutive patients who underwent PVP procedures performed at our center and returned for at least one post operative evaluation after 3 months. All had standardized clinical evaluations within 1 week before surgery and every 3 to 6 months after surgery. Data were collected during ′on′ and practically defined ′off periods for the Unified Parkinson′s Disease Rating Scale (UPDRS), Hoehn and Yahr stage, Schwab and England Activities of Daily Living (ADL) scale, and movement and reaction time. In addition, the severity and anatomic distribution of dyskinesia, neuropsychological status, average percent of ′on′ time with and without dyskinesia, and clinical global impression were assessed during a longitudinal follow-up. Results.: Eighty-nine patients (46 men) underwent unilateral PVP while 12 patients (6 men) had staged bilateral PVP. At 3 months after unilateral or staged bilateral PVP, 84 of the 101 patients reported marked or moderate improvement in their parkinsonian symptoms. Postoperative UPDRS mean total motor score improved in the 'off state by 35.5% and the mean ADL score by 33.7% (p＜0.001). Rigidity, b radykinesia, and tremor scores also markedly improved after PVP, particularly on the contralateral side. Levodopa-induced dyskinesia was markedly reduced while daily 'on′ time increased by 34.5% (p＜0.001). Seven patients had transient peri-operative complications including confusion, expressive aphasia, pneumonia, and visual changes. Improvements in parkinsonian symptoms were maintained in both ‘off’ and ‘on’ states in 67 patients at 12 months after PVP and in 46 patients who were followed for a mean period of 26.3 months. Patients who underwent staged bilateral PVP benefited further from the second procedure. Five of 12 patients experienced some adverse event. Conclusion.: Based on this large series of patients with extended follow-up, we conclude that PVP is an effective and relatively safe treatment for medically resistant PD, especially for dopa-induced dyskinesia, tremor, rigidity, and bradykinesia. Motor fluctuations also improved. Benefits are most noticeable on the side contralateral to the PVP. Clinical improvement has been sustained for longer than 2 years.