Functional Dyskinesias following Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease: A Report of Three Cases.

Background: Functional (psychogenic) dyskinesias in patients with Parkinson's disease (PD) are exceedingly rare.

Cases: Herein we report three patients with PD who presented with functional dyskinesias in the first 3 months after subthalamic nucleus deep brain stimulation (DBS). All patients presented with chorea mimicking levodopa or stimulation-induced dyskinesias in the first 24 hours following stimulation adjustment. Two patients had generalized chorea and one, hemichorea. In all patients the abnormal movements could be induced or resolved with placebo/nocebo changes to the stimulation parameters. Following the diagnosis of a functional movement disorder (FMD), all patients improved with appropriate management.

Conclusions: Functional chorea following DBS might mimic organic dyskinesias in PD but can be accurately diagnosed using suggestibility and placebo responses to sham stimulation adjustments. Recognizing the presence of FMD following DBS is important for proper management of these patients.