490 Unilateral Subthalamic Nucleus Deep Brain Stimulation Improves Motor Symptoms Without Neurocognitive Worsening in Parkinsons Disease

Abstract

INTRODUCTION: Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established surgical intervention for patients with medically refractory Parkinson’s disease (PD). Numerous reports have described adverse nonmotor side effects, such as declines in verbal fluency and working memory, following bilateral implantation. Unilateral STN DBS is a possible alternative; however, it remains unclear whether unilateral implantation meaningfully reduces harmful effects on cognition. METHODS: This retrospective cohort study utilized chart review to collect pre- and postoperative Unified Parkinson’s Disease Rating Scale (UPDRS)-III, Levodopa Equivalent Daily Dosage (LEDD), imaging, and neurocognitive test results from 32 patients (unilateral, n = 12; bilateral, n = 20). For all statistical comparisons, p-values less than or equal to 0.05 were considered statistically significant. Student’s unpaired and paired T-tests were used to assess for differences between groups and within groups, respectively. RESULTS: There was no difference across 17 preoperative neurocognitive tests. Both unilateral and bilateral STN DBS resulted in significant decreases in postoperative UPDRS-III and LEDD (unilateral: p < 0.0001; bilateral: p < 0.0001) scores. There were no differences in the absolute decreases in UPDRS (p=0.055) and LEDD (p=0.120) scores between the groups. The bilateral STN DBS group had a significant deterioration in verbal fluency (COWAT FAS, p = 0.002; COWAT Animals, p = 0.014) and attention/executive function (Trails A, p=0.049 and Trails B, p = 0.011) compared to the unilateral group. CONCLUSIONS: Unilateral STN DBS is an effective and safe treatment option for patients with advanced PD. Particularly for patients with asymmetric motor symptoms, unilateral implantation provides a meaningful improvement in motor symptoms and reductions in dopaminergic medications without the risk of neurocognitive decline seen in bilateral implantation.