Clinical utility of deep brain stimulation in an advanced Parkinson's disease

Introduction. Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidus internus (GPi) have demonstrated efficacy in advanced Parkinson's disease (PD). We aimed to assess the clinical utility of these procedures in terms of the quality of life, and to determine the pre and postsurgical characteristics related to the outcome. Method. A prospective study was conducted on a cohort of 20 patients with advanced PD who underwent bilateral DBS: 14 in STN and 6 in GPi. They were assessed according to the CAPSIT-PD protocol before and after surgery, with a mean follow-up of 9 and 11 months, respectively. The main outcome variables were change in the UPDRS III score in off (efficacy) and the PDQ-39 quality of life questionnaire score (clinical utility). Results. The STN group improved theirs UPDRS III in off by a mean of 35 % (p = 0.001) and their PDQ-39 by 21 % (p = 0.026). The GPi group improved their UPDRS III in off by 21 % (p = 0.028) and their PDQ-39 by 37 % (p = 0.116). The presurgical levodopa-equivalent dose was a positive predictor of the efficacy and clinical utility of STN DBS and a negative predictor of the efficacy of GPi DBS. In both groups, the clinical utility was determined by improvement in functional disability in off scales. Conclusions. Bilateral DBS demonstrated middle-term efficacy and clinical utility in the treatment of advanced PD. The presurgical levodopa-equivalent dose was a predictor of the efficacy and clinical utility of DBS.