Evaluation of the effect of bilateral subthalamic nucleus deep brain stimulation on fatigue in Parkinson's Disease as measured by the non-motor symptoms scale.

Background: Fatigue is a common and disabling non-motor symptom (NMS) in Parkinson's disease (PD) patients. However, the effect of subthalamic nucleus (STN) deep brain stimulation (DBS) on fatigue has not been widely studied.

Objective: To determine the effect of STN DBS on fatigue in PD patients, measured by the Non-motor symptoms scale (NMSS).

Methods: Cross-sectional analysis of 50 patients with PD who underwent STN DBS at King's College Hospital and Salford Royal Hospital with fatigue scores (measured by question number 4 from domain 2 (sleep/fatigue) of the NMSS as the primary outcome measure. Secondary outcome measures included the PD Sleep Scale (PDSS), Scales for Outcome in PD (SCOPA)-motor examination, activities of daily living, motor complications, Hoehn and Yahr (HY) stage and changes in Levodopa Equivalent Daily Dose (LEDD).

Results: 50 patients with a mean follow-up period of 1.98 ± 1.36 years were studied. Significant improvement in median fatigue scores (4.00 (0.75-9.00) to 1.00 (0.00-4.50);  = .001) was observed. In addition, improvements in question 5 (sleep maintenance and fragmentation; 8.00 (4.00-12.00) to 0.00 (0.00-4.00);  < .001) and in domain 2 total score (sleep/fatigue; 20.00 (8.75-27.25) to 6.00 (0.75-16.00);  < .001) were also significant, together with improvements in NMSS total score, SCOPA scores and HY stage ( ≤ .02). Moreover, LEDD but especially dopamine agonists LEDD was significantly reduced after DBS (310.00 (0.00-480.00) to 150.00 (0.00-300.00);  < .020).

Conclusions: Even though open label and not using a validated fatigue scale, this observational analysis suggest that fatigue improves significantly after STN DBS with persisting benefits at two years follow-up.