Early versus Late Application of Subthalamic deep brain Stimulation to Parkinson's disease patients with motor complications (ELASS): protocol of a multicentre, prospective and observational study.

Introduction: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established surgical treatment for Parkinson's disease (PD). However, there is currently no consensus on the best timing for this surgery. The aim of our study is to compare the therapeutic efficacy of bilateral STN DBS in patients with PD with early and late motor complications.

Methods And Analysis: 200 patients with PD will be enrolled in this multicentre, prospective, observational study, and will be followed up for 4 years. Patients with PD who meet the criteria for STN DBS surgery will be allocated to either the early stimulation group or the late stimulation group based on the duration of their motor complications. The primary outcome will be changes in quality of life from baseline to 4 years, measured using the 39-item Parkinson's Disease Questionnaire Summary Index. The secondary outcomes include changes in motor function measured using Movement Disorder Society-revised Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III, self-reported experiences of daily living measured using MDS-UPDRS Part I B and Part II, good 'on' time recorded by the patients using a diary and safety profile of both groups.

Ethics And Dissemination: The study received ethical approval from the Medical Ethical Committee of the First Affiliated Hospital, Sun Yat-sen University. The results of this study will be published in peer-reviewed journals and presented at international conferences.

Trial Registration Number: NCT01922388; Pre-results.