What Cochlear Implantation with Attempted Hearing Preservation in Widened Vestibular Aqueduct Adds to Understanding About the Etiology and Pathogenesis of Hearing Loss: A Systematic Review

Widened vestibular aqueduct (WVA) is the commonest congenital inner-ear malformation associated with childhood sensorineural hearing loss. Proposed pathophysiological mechanisms include abnormal endolymph-perilymph pressure regulation, hyperproteinaceous perilymph and impaired ionic homeostasis, particularly in SLC26A4-related disease. These vulnerabilities have raised concerns about the feasibility of hearing preservation cochlear implantation (HPCI). The study aims to evaluate HPCI outcomes in children with WVA and identify prognostic factors that may clarify underlying pathophysiology. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review (PROSPERO CRD420251128410) of MEDLINE, Embase, Cochrane Library, and CINAHL from inception to November 2025 identified studies reporting pre- and postoperative unaided thresholds in WVA cochlear implant recipients. Two reviewers independently screened and extracted data. Heterogeneity in outcome definitions required narrative synthesis. Five observational studies including 58 WVA patients (228 total across all cohorts) met inclusion criteria. Hearing preservation ranged from 20%-83% using a variation of outcome criteria. Studies reported improved outcomes with round-window insertion, soft-surgery techniques, and lateral-wall electrodes. In the largest regression analysis, WVA independently predicted poorer preservation. SLC26A4-related WVA did not preclude preservation, and several cohorts reported small postoperative low-frequency threshold changes (<20 dB) despite universal perilymph leakage and varied sealing methods. No study quantified perilymph flow or assessed postoperative vertigo. Hearing preservation cochlear implantation in WVA is feasible, though outcomes vary. Evidence suggests deterioration may relate more to intrinsic abnormalities in cochlear pressure regulation and epithelial physiology, and to potential suction-related trauma, than to perilymph loss alone. Standardized audiometric reporting and integrated anatomical and genetic phenotyping are needed to refine prognostication for children born with WVA.