Present role of stereotactic thalamotomy for parkinsonism. Retrospective analysis of operative results and thalamic lesions in computed tomograms.

14 cases of unilateral and 5 cases of bilateral thalamotomy for parkinsonism were reviewed, with 32-144 months' (mean 67.8) and 54-212 months' (mean 110) follow-up, respectively, after the initial operation. Rigidity and tremor disappeared in approximately 80% of cases and was reduced in the remaining 20%. 68% improved by one or two grades in the Hoehn-Yahr scale after operation. Thalamotomy abolished dyskinesias and on-off phenomena on the operated sides. 36% of cases discontinued levodopa therapy after operation. CT study of the lesions suggested that destruction of a large part of basal Vop was most important to obtain the best results.