Deep Brain Stimulation Effects on Olfactory Dysfunction of Parkinson’s Disease - A Meta-Analysis

Abstract

Background: Non-motor symptoms in PD usually arise at very early stage and suffer the damage decades from diagnose. Deep brain stimulation (DBS) is considered as a highly efficient treatment option for PD’s motor function. However, the effect of DBS on NMS, especially hyposmia, has not been fully understood and there are contradictory data among different researches.Objective: The objective of this study was to evaluate the therapeutic effect of DBS on hyposmia in PD patients with a cohort study and identified whether the olfactory function scores influence the final surgery effect.Methods: A meta-analysis including six studies with 326 patients were conducted to evaluate the exact therapeutic effect of DBS on hyposmia in PD. Sub-group analyses based on sample size, gender, stimulation parameters were carried out to distinguish the difference. Sensitivity analysis was conducted to evaluate studies’ heterogeneity and stability. Potential publication bias were evaluated by Egger’s tests and the funnel plots.Results: Our study showed that DBS had clearly improved olfactory function in Parkinson patients (P < 0.0001) and the group heterogeneity as well as the publication bias advocate the convince of the result (Heterogeneity: Chi² = 6.39, df = 5 (P = 0.38); I² = 22%). Subgroup analysis also found that different groups of gender, education level or stimulation parameters have no obvious discrepancy on olfactory function improvement except age groups.Conclusion: In summary, this article summarize studies about DBS and hyposmia and offer evidences for the notion that DBS has authentic therapeutic value on the hyposmia in PD.