Aging and Hearing with Vestibular Schwannoma Beyond Presbycusis: A Large Cross-Sectional Audiometric and Volumetric...

To identify predictors of auditory function in treatment-naïve vestibular schwannomas (VS) while accounting for age-related hearing loss, investigating baseline volumetrics and audiometrics in a pre-intervention stereotactic radiosurgery (SRS) cohort.

Cross-sectional study.

Single-center national SRS referral program with a prospective database.

All consecutive patients with newly diagnosed unilateral VS and complete pre-intervention imaging and audiometric data were included. High-definition MRI and bone CT with co-registration and fusion enabled morphometric and volumetric analysis of VS and internal auditory canal (IAC) dimensions. Univariate tests, multivariate logistic regression with interaction terms, and regularized regression identified factors associated with serviceable hearing (Gardner-Robertson scores 1-2).

Among 533 patients (50.65% male, mean age 57.04 years), 72.6% had serviceable hearing. Median VS volume was 875.3 mm³ (IQR: 328.6-1732.5). The final multivariate model (AUC = 0.719) retained age (OR = 0.920, P = .0144), canal filling ratio (CFR; OR = 0.465, P = .0446), and a significant age × intracanalicular-to-total tumor volume ratio interaction (P = .0318). Age-stratified analyses revealed that the CFR-hearing relationship reversed across age groups: in younger patients (<40 years), higher canal filling was associated with better hearing preservation (94% vs 73%), while this pattern reversed in older patients (>60 years). Younger patients also demonstrated greater canal dilation (P = .002), though this lacked independent predictive value (P = .366).

While age dominates hearing prediction in VS, canal filling ratio significantly modifies this relationship in an age-dependent manner, representing a clinically accessible imaging biomarker with age-specific thresholds and effects.