Possible mechanisms involved in subthalamotomy-induced dyskinesia in patients with Parkinson's disease.

ABSTRACT

BACKGROUND/AIMS: Operation-induced dyskinesia (OID) occurs in approximately 10% of patients submitted to subthalamotomy. The goal of the authors was to determine the possible causes of this feared complication. METHODS: The 54 patients who underwent unilateral subthalamotomy were divided into two groups the OID group (OIDG), composed of 6 patients who developed dyskinesia following the operation, and the control group (CG), consisting of 48 patients who did not present this complication. The two groups were compared regarding age; sex; presence of levodopa-induced dyskinesia (LID) and/or stimulation-induced dyskinesia (SID); side of the operation; territories of the subthalamic nucleus (STN) involved by the lesion, and degree of lesion extension towards the zona incerta (ZI). RESULTS: The lesion involved the dorsolateral territory of the STN and was almost completely restricted to this nucleus in all patients of the OIDG, while it spread to the ZI in all but 1 patient of the CG. SID was significantly (p < 0.05) more frequent in the OIDG. There was also a strong trend favoring LID (p = 0.055). CONCLUSIONS: Damage to the dorsolateral territory of the STN and sparing of the ZI seem to be essential for the development of OID. SID and, to a lesser extent, LID are apparently significant risk factors for the development of this complication.