Variable versus constant frequency deep brain stimulation in patients with advanced Parkinson’s disease: study protocol for a randomized controlled trial

Abstract

Background: Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) can be used to treat motor symptoms and dyskinesia in the advanced stages of Parkinson’s disease (PD). High frequency stimulation (HFS) of the STN can lead to consistent, long-term improvement of PD symptoms. However, the effects of HFS on the axial symptoms of PD, specifically freezing of gait (FOG), can be limited or cause further impairment. While this can be alleviated via relatively low frequency stimulation (LFS) in select patients, LFS does not control all motor symptoms of PD. Recently, the National Engineering Laboratory for Neuromodulation reported preliminary findings regarding an efficient way to combine the advantages of HFS and LFS to form variable frequency stimulation (VFS). However, this novel therapeutic strategy has not been formally tested in a randomized trial. Methods/Design: We propose a multicenter, double blind clinical trial involving 12 study hospitals and an established DBS team. The participants will be divided into a VFS and a constant frequency stimulation (CFS) group. The primary outcome will be changes in Stand-Walk-Sit (SWS) task scores at three months of treatment in the “medication off” condition. Secondary outcome measures include specific item scores on the Freezing of Gait Questionnaire and quality of life. The aim of this trial is to investigate the efficacy and safety of VFS compared with CFS. Discussion: This is the first randomized controlled trial to comprehensively evaluate the effectiveness and safety of VFS of the STN in patients with advanced PD. VFS may represent a new option for clinical treatment of PD in the future. Trial registration: The present protocol is registered at ClinicalTrials.gov: NCT03053726.