The effects of bilateral subthalamic nucleotomy were reported earlier than unilateral subthalamotomy. One early report of two patients claimed that small lesions in the dorsolateral STN could reduce the off motor UPDRS scores by over 68%, without inducing dyskinesia (111). Both patients were reported to have no complications and to have medication withdrawn. This group later reported that bilateral subthalam-otomy had been accomplished safely in five subjects (105). Detailed imaging was not presented. A larger series of seven staged bilateral and 11 simultaneous procedures was reported to show a 50% reduction in off parkinsonism, 36% reduction in on-period parkinsonian features, 50% reduction in dyskinesia, and 47% reduction in levodopa-equivalent medication at three years of follow-up. Three patients had severe long-term dysarthria, whereas 11/18 had intraoperative or transient postoperative mild chorea. In three cases, the chorea lasted for three to six months before resolving fully (112). Merello et al. (113) described two patients who, preoperatively, had amantadine-responsive levodopa-induced dyskinesia and who received bilateral subthalamotomy. Immediate postoperative unilateral chorea ensued, which persisted despite cessation of levodopa. The addition of amantadine in the first month had no effect on the dyskinesia. The dyskinesia resolved spontaneously within six months. This observation suggests that the pathophysiology of levodopa-induced dyskinesia and subthalamotomy-induced dyskinesia differs.
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