Globus pallidus internus deep brain stimulation improves axial symptoms of Parkinson patients after long-term subthalamic nucleus stimulation: A case series study

Introduction: Some patients with advanced Parkinson's disease (PD) develop refractory axial symptoms and motor complications following initially effective subthalamic nucleus (STN) deep brain stimulation (DBS). We aim to determine whether globus pallidus internus (GPi) stimulation can improve refractory axial symptoms and dyskinesia, as well as psychosocial functioning and quality of life, in this group of patients who no longer benefit from STN DBS. Methods: In this pilot study, bilateral pallidal stimulation treatment was given to 7 patients with advanced PD who had developed refractory axial symptoms, including speech and swallowing difficulties, and painful dyskinesia, after long-term (> 5 y) subthalamic stimulation. The follow-up period was 6?months. Primary clinical outcome measures focused on motor symptom severity, motor complications, psychosocial function, and quality of life. Secondary outcome measures included daily dose of antiparkinsonian medication and patient's body weight. Results: After pallidal stimulation, patients showed an overall 44% improvement in motor symptom scores at 6-month follow-up along with a 49% improvement in dyskinesia, a 33% improvement in psychosocial functioning, and a 42% improvement in quality of life. No adverse events occurred during the study. Conclusions: These initial results indicate that bilateral GPi DBS could provide significant clinical benefits to patients whose axial symptoms cannot or can no longer be controlled by STN DBS.