Tracking Lymphatic Drainage Pathways Through Inner Ear Channels: A Systematic Review.

The search for potential lymphatic routes through the cochlea, or membranous portions of the inner ear labyrinth, remains a significant challenge. Researchers often focus on lower mammals rather than humans to uncover these pathways. This review aims to delineate the speculated lymphatic routes within the inner ear to date. It follows the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, conducting a comprehensive search of PubMed, Scopus, Crossref, and Google databases using the terms "inner ear" and "lymph." The problem, intervention, comparison, outcome (PICO) search strategy was employed, and analysis was performed using equation and scope metrics. Articles were screened and filtered using the CADIMA automation tool, resulting in 33 articles being reviewed, of which 23 were selected. Potential lymphatic drainage routes identified include the round window, oval window, scala tympani, spiral limbus, and lateral wall of the cochlea. The vestibular side of Reissner's membrane was noted as a key nodal point for lymphocytes within the inner ear. This review maps the proposed lymphatic networks in the inner ear and highlights existing gaps. It systematically gathers, evaluates, and synthesizes available evidence on the lymphatic pathways of the inner ear, offering valuable insights into their presence, structure, function, and clinical significance.