Subthalamic nucleus deep brain stimulation outcome in young onset Parkinson's disease: a role for age at disease onset?

Background: Patients with young onset Parkinson's disease (YOPD) are often candidates for subthalamic nucleusedeep brain stimulation (STNeDBS). Nevertheless, few data have been reported on the long term STNeDBS clinical outcome of YOPD versus nonyoung onset Parkinson's disease (n-YOPD) patients. Aim In this study, the issue of whether YOPD might represent a long term positive predictive factor for STNeDBS was addressed, comparing follow-up data for 20 YOPD and 40 n-YOPD patients (20 treated after <15 years of disease duration and 20 treated after ≥15 years of disease duration). Materials and methods: Mean scores for the Unified Parkinson's Disease Rating Scale (UPDRS) sections were compared 1 year, 5 years and, for 34 patients (12 YOPD and 22 n-YOPD), ≥7 years after surgery. Furthermore, a Cox proportional hazard regression model was used to determine the influence of age at PD onset, clinical phenotype, disease duration and duration of motor complications on the development of stimulation and medication resistant symptoms. Results: YOPD patients showed a lower incidence of stimulation and medication resistant symptoms and a lower mortality rate; also, the tremor dominant clinical phenotype was associated with a lower risk of developing dementia, hallucinations and constipation. No significant differences in UPDRS scores were observed between n-YOPD patients treated after <15 years of PD and those treated after ≥15 years of PD. Conclusion: In this series of STNeDBS treated patients, YOPD was associated with a medium to long term lower incidence of stimulation and medication resistant symptoms.