Levodopa-induced dyskinesias treated by pallidotomy.
Pallidotomy has been reported to improve parkinsonian symptoms, but its effects on levodopa-induced dyskinesia (LID) have not been thoroughly examined. We describe here the results of stereotactic, unilateral, posteroventral pallidotomy on LID in 42 patients (22 women), who were followed for up to 9 months. Their mean age was 60. 6+/-9.3 (range: 40-74), age at onset was 46.1+/-9.1 (range: 24-46), and duration of symptoms was 14.5+/-5.3 (range: 4-25) years. Three months following pallidotomy, the percent time with dyskinesia decreased from 37.0 to 17.3 (P<0.0001) and the percent time the patients were 'on' with dyskinesias decreased even more, from 71.0 to 22.9 (P<0.0001). Furthermore, the number of patients with troublesome (moderate to violent) dyskinesia had decreased from 36 (86%) prior to surgery to only 5 (12%) after surgery. The mean unified Parkinson disease rating scale (UPDRS) scores for LID-related disability and pain decreased from 1.95 to 0.74 (P<0. 0001) and from 1.02 to 0.17 (P<0.0001), respectively. Since the pre- and post-pallidotomy daily levodopa dosage remained essentially the same, the improvement in LID could not be attributed to a reduction in levodopa. Surgery-related complications occurred in eight (19%) patients, but none of them had persistent disability as a result of these complications. We conclude that pallidotomy is an effective and safe procedure in the treatment of medically intractable LID.