The impact of bilateral subthalamic stimulation on non-motor symptoms of Parkinson's disease

To evaluate the impact of bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) on the prevalence of non-motor symptoms reported by Parkinson's disease (PD) patients one year following surgery and to examine whether there was an association between number of non-motor symptoms reported and quality of life (QoL).

Twenty-four patients who received bilateral STN DBS and had follow-up evaluations one year after surgery were included in this study. Patients' motor function was evaluated with the Unified Parkinson's Disease Rating Scale, non-motor symptoms were assessed with the Non-Motor Symptom questionnaire (NMSQuest) and quality of life was assessed with the PDQ-39.

There was a mean of 12 non-motor symptoms reported prior to surgery which was significantly reduced to a mean of 7 symptoms one year after surgery. Autonomic symptoms were the most frequently reported and demonstrated the greatest reductions following surgery. Twenty-seven of the 30 items represented in the NMSQuest were reported less frequently one year after surgery compared to before surgery. The reduction in non-motor symptoms was significantly correlated with total QoL scores and the subscales of mobility, activities of daily living, cognition and bodily discomfort.

Non-motor symptoms are common in patients with advanced PD. The number of non-motor symptoms was significantly decreased one year following bilateral STN DBS which was associated with a significant improvement in QoL. Further studies focused on specific non-motor symptoms are warranted in order to fully understand the impact and mechanisms of STN DBS on these symptoms.