Treatment of advanced Parkinson's disease by unilateral posterior GPi pallidotomy: 4-year results of a pilot study

To assess the long-term outcome following unilateral pallidotomy for advanc ed Parkinson's disease, we performed nonblinded Core Assessment Program for Intracerebral Transplantations protocol assessments in 10 of the original 15 patients in our pilot study for 4 years following surgery. Although Unif ied Parkinson's Disease Rating Scale motor examination scores returned to b aseline levels at 3 and 4 years, most patients continued to show sustained improvements in contralateral tremor, akinesia, and drug-induced dyskinesia s. Contralateral tremor was absent at 4 years in all seven patients with pr eoperative tremor. Contralateral "aff"' arm movement times (averaged for th ree tasks) decreased by 37% at 1 year and by 30% at 4 years. Contralateral dyskinesia scores improved by 82% at I year and by 64% at 4 years. In contr ast, after reaching speeds equal to the contralateral side at I year, ipsil ateral "off" movement times increased by 13% over baseline levels at 4 year s. Although most gait and postural stability measures showed modest initial improvement followed by a return to baseline values, "on" stand-walk-sit t ask performance declined significantly at 4 years. Despite the restriction of our surgeries to one side and the expected natural progression of Parkin son's disease, the results of patient self-assessments suggest that 4 years after unilateral pallidotomy, most patients continue to experience a quali ty of life above preoperative levels.