Effect of deep brain stimulation on patients with Parkinson's disease with excessive daytime sleepiness.

Background: Excessive daytime sleepiness (EDS) is a prevalent non-motor symptom in Parkinson's disease (PD), significantly impairing quality of life. While deep brain stimulation (DBS) effectively improves motor symptoms, its impact on EDS remains unclear.

Objective: This systematic review aims to evaluate the effects of DBS on EDS in patients with PD.

Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search of PubMed, Scopus, Embase and PsycInfo databases published by 2024) was conducted using terms related to DBS, EDS and PD. 20 studies met the inclusion criteria. Data on demographic characteristics, DBS parameters, sleep assessment scales and Levodopa-equivalent daily dose (LEDD) changes were extracted and analysed.

Results: Among the 20 studies, 9 reported improvements in EDS post-DBS, with a mean Epworth Sleep Scale (ESS) reduction of 26.8%. However, 11 studies found no significant change. All studies reported LEDD reductions (mean 47.7%), but only two demonstrated a significant correlation between LEDD reduction and ESS improvement. Notably, some studies revealed discrepancies between subjective improvements in sleep quality and objective measures.

Conclusion: The effect of DBS on EDS in PD remains inconclusive, with mixed findings across studies. While DBS consistently reduces LEDD and improves overall sleep quality, its direct impact on EDS varies. Further research with larger cohorts, objective sleep assessments and focus on confounders is necessary to elucidate DBS's role in managing EDS in patients with PD.