Supplementary Material for: Globus Pallidus Internus Deep Brain Stimulation as Rescue Therapy for Refractory Dyskinesias following Effective Subthalamic Nucleus Stimulation

Background: Deep brain stimulation (DBS) at the subthalamic nucleus (STN) or globus pallidus internus (GPi) can effectively treat the motor symptoms of Parkinson's disease, but dual implantation is rare. We report the first cases of additional GPi stimulation as rescue therapy for disabling dyskinesias following successful STN stimulation. Methods: Two patients, initially treated with bilateral STN DBS, underwent subsequent bilateral GPi DBS after the development of refractory dyskinesias within 1 and 6 years of STN surgery. Patients were evaluated with the Unified Parkinson's Disease Rating Scale (UPDRS) before and after surgeries for STN and GPi DBS. Results: GPi DBS effectively suppressed dyskinesias in these patients and improved their quality of life, as demonstrated by their videos and UPDRS scores. Conclusions: Additional bilateral GPi DBS may be considered in the rare instance of patients who develop refractory dyskinesias early or late after bilateral STN DBS.