Lymphatic and Glymphatic Alterations in Auditory Disorders: A Rapid Review-Informed Systematic Review and...

Background and Objectives: The inner ear has traditionally been regarded as an immunoprivileged and anatomically isolated organ. However, growing interest in neuro-lymphatic interactions has raised the hypothesis that glymphatic and lymphatic mechanisms may contribute to auditory pathology and its association with cognitive dysfunction. This systematic review aimed to synthesize current human evidence regarding anatomical, imaging, and clinical correlates of glymphatic mechanisms in the inner ear and audiological pathologies, and to quantitatively evaluate currently available biomarkers. Materials and Methods: A structured search of PubMed, Scopus, and Cochrane databases was performed from inception through March 2026. Eligible studies included human investigations reporting anatomical, histopathological, or MRI-based glymphatic assessments related to inner ear disorders. Risk of bias was assessed using the Newcastle-Ottawa Scale and Joanna Briggs Institute tools. Meta-analysis was conducted for diffusion tensor image analysis along the perivascular space (DTI-ALPS) indices comparing auditory disorders with healthy controls. Results: Six studies met inclusion criteria (five cross-sectional imaging studies and one surgical histopathological case series). Histopathology demonstrated lymphatic capillaries in advanced Ménière disease. MRI studies consistently reported reduced ALPS indices and/or increased choroid plexus volume and enlarged perivascular spaces in tinnitus, congenital sensorineural hearing loss, and age-related hearing loss. Meta-analysis of five studies showed a significant reduction of ALPS index in auditory disorders compared with controls (SMD = -0.73, 95% CI -0.90 to -0.55; p < 0.001), with no heterogeneity. Glymphatic markers were frequently associated with audiological data, cognitive performance and inflammatory biomarkers. Conclusions: Human evidence supports the presence of altered central glymphatic function across diverse auditory phenotypes. Although predominantly based on indirect MRI proxies and cross-sectional data, the meta-analytic findings strengthen the biological plausibility of an auditory-glymphatic interaction. Prospective longitudinal studies are warranted to clarify causality and therapeutic implications.