Non-motor effects of deep brain stimulation in dystonia: A systematic review

INTRODUCTION: Deep brain stimulation (DBS) has emerged as an effective treatment in medically intractable dystonia, with the globus pallidus internus (GPi) being most frequently targeted. Non-motor symptoms, including pain and psychiatric, cognitive and sleep disturbances, are increasingly recognized as important determinants of disease burden in dystonia patients. We reviewed non-motor outcomes of DBS in dystonia, focusing on GPi-DBS. METHODS: A systematic literature search of Pubmed and Embase was performed according to the PRISMA guidelines. RESULTS: Fifty-two studies were included. GPi-DBS reduced pain related to dystonia. No major effects on anxiety, mood, and cognition were found. In contrast to motor outcome, non-motor outcome seems more independent of the etiology of dystonia. However, the impact of potential confounders (e.g. patient factors, changes in pharmacological treatment) is unclear. CONCLUSION: Despite the growing interest in non-motor symptoms in dystonia, DBS studies still focus primarily on motor outcome. We recommend systematic evaluation of both non-motor and motor features before and after DBS interventions to improve quality of life and management of patients with dystonia