Bilateral Subthalamic Stimulation can Improve Sleep Quality in Parkinson's Disease

Background: Sleep problems are among the most common non-motor symptoms of Parkinson's disease (PD). The PD Sleep Scale 2nd version (PDSS-2) improved the original PDSS by adding more items on different aspects of sleep problems, making it a more robust tool to evaluate the severity of sleep disturbances. However, previous studies on deep brain stimulation (DBS) have not used the PDSS-2. Objective: To determine if the PDSS-2 could detect improvement reliably in sleep problems after bilateral subthalamic nucleus DBS for PD. Methods: In this prospective study, 25 consecutive patients undergoing DBS implantation were enrolled. Patients were examined twice: 1 week prior to the DBS implantation (baseline) and 12 months postoperatively. Severity of PD symptoms were assessed by the Movement Disorders Society Unified PD Rating Scale (MDS-UPDRS) and the Non-Motor Symptoms Scale (NMSS). Presence and severity of sleep disturbances were specifically measured by PDSS-2. Results: Total score of MDS-UPDRS improved from 81 (median, interquartile-range: 63-103) to 55 points (median, IQR: 46-75, p < 0.001). Health-related quality of life, measured by PDQ-39, also improved from 29 (IQR: 18-40) to 15 (IQR: 9-28) points (p = 0.002). Most domains of NMSS also improved. At baseline 13 patients reported sleep problems, but 1 year after DBS implantation only 3 did (p = 0.012). Although only 6 out of 15 items showed a significant decrease after DBS implantation, the total score of PDSS-2 decreased from 24 (IQR: 17-32) to 10 (IQR: 7-18) points (P < 0.001). Conclusions: Based on our results, PDSS-2 can detect improvements in sleep quality reliably after DBS implantation.