Long-term effects of pallidal or subthalamic deep brain stimulation on quality of life in Parkinson's disease

We assessed the effects of deep brain stimulation of the subthalamic nucleus (STN-DBS) or internal pallidum (GPi-DBS) on health-related quality of life (HrQoL) in patients with advanced Parkinson's disease participating in a previously reported multicenter trial. Sickness Impact Profile (SIP) questionnaires were available for analysis in a subgroup of n = 20/20 patients with GPi-DBS and n = 45/49 patients with STN-DBS at baseline, 6 and 36 months. The SIP provides a physical dimension and a psychosocial dimension sum score and 12 category scores: Alertness/Intellectual Behavior (AIB), Ambulation (A), Body Care and Movement (BCM), Communication (C), Eating (E), Emotional Behavior (EB), Home Management (HM), Mobility (M), Recreation and Pastimes (RP), Sleep and Rest (SR), Social Interaction (SI), and Work (W). Motor functioning was assessed by means of the Unified Parkinson's Disease Rating Scale and diaries. At 6 months significant improvements in off-period motor symptoms and activities of daily living were paralleled by significant reductions in the total, physical, and psychosocial SIP score in both treatment groups. At 3 years, sustained improvements were observed in the physical dimension score, BCM, E, M, RP after STN-DBS and M, SI after GPi-DBS. All other SIP subscores approached baseline values, but were still the same or better (except C) whereas motor functioning remained stable after 36 months. STN-DBS and GPi-DBS led to significant early improvements in HrQoL. Despite sustained motor improvements many of these initial benefits were lost after 3 years. This may reflect either progression of the disease or adaptive changes in the subjective perception of health-related wellbeing over time.