BACKGROUND: The well known global improvement of quality of life (QoL) after 
bilateral high frequency chronic deep brain stimulation of the subthalamic 
nucleus (STN DBS) in Parkinson's disease (PD) is in contrast to behavioral 
disturbances as observed after surgery. Indeed the impact of DBS on physical 
versus mental aspects of QoL in PD remains unknown.
OBJECTIVE: To assess the influence of bilateral STN DBS on physical versus 
mental aspects of QoL in Parkinson's disease.
METHODS: The results of 27 patients for the Unified Parkinson's disease Rating 
Scale (UPDRS), Parkinson's Disease Questionnaire 39 (PDQ39) and Short Form 36 
health survey questionnaire (SF36) were compared before surgery and after 12 
months of bilateral STN DBS.
RESULTS: Comparing off-dopa conditions before versus 12 months after surgery, 
both UPDRS part II and part III significantly improved: 32.6% and 52%, 
respectively. UPDRS part I scores did not change significantly at 12 months. As 
for PDQ39, the global score significantly improved after surgery (21.1 %) as did 
four subscores: mobility (25.6 %), activity of daily living (34.5 %), stigma 
(40.1 %) and bodily discomfort (30 %). Three PDQ39 subscores, however, showed no 
significant changes: emotional well-being (10.7 %), social support (3.2%) and 
cognition (8.5 %) and one item even worsened: communication (-7.7 %). In SF36, 
only physical items significantly improved.
CONCLUSION: Using clinician's based rating scale, bilateral STN DBS showed 
significant improvement in PD patients at 12 month follow up. However, using 
patient's self-assessment scales, the clinical benefit of STN DBS was more 
subtle: physical items of QoL significantly improved, whereas mental items such 
as emotional well-being, social support, cognition and communication showed no 
improvement. Our results are suggestive of a dissociation of motor and non-motor 
symptoms control after bilateral STN DBS in PD patients.