Vestibular schwannoma-related increased labyrinthine post-gadolinium 3D-FLAIR signal intensity and association with hearing impairment.

Abstract

BACKGROUND AND PURPOSE Vestibular schwannomas (VSs) are benign neurogenic tumors commonly associated with progressive unilateral hearing loss, tinnitus, and vestibular symptoms. Growing evidence links signal changes in the VS-adjacent labyrinth with sensorineural hearing loss. This study seeks to quantify the association of labyrinthine signal on post-gadolinium 3D-FLAIR imaging correlates with hearing loss and to evaluate potential longitudinal changes over time. MATERIALS AND METHODS Selected patients were identified from a prospectively maintained VS registry. Mean signal intensity ratios of the bilateral labyrinth and pons were measured on 3D-FLAIR post-gadolinium MRI. Correlations with paired audiometric data including pure tone average (PTA), word recognition score (WRS), and AAO-HNS hearing class within one year were evaluated. RESULTS 125 studies obtained from 2015 to 2022 among 66 patients undergoing observational management for sporadic VS were analyzed. Increased signal intensity was noted of the VS-affected labyrinth/contralateral labyrinth (mean ratio 1.56, SD 0.58). Increased signal intensity was associated with increased PTA on both labyrinthine (correlation coefficient [CC] 0.20, p=0.03) and pontine comparisons (CC 0.24, p=0.006), and with decreased WRS on pontine comparisons (CC -0.18, p=0.04). Increased signal intensity was significantly associated with non-serviceable AAO-HNS C/D hearing when intensities were compared to the pons (p=0.01) but not the contralateral labyrinth (p=0.1). Among 44 patients with available follow-up, no statistically significant associations were identified between audiometric data and signal changes over the same interval. CONCLUSIONS Increased 3D-FLAIR post-gadolinium labyrinthine signal is associated with sensorineural hearing loss; however, its relationship with hearing trajectory remains unclear. Overall findings suggest that while post-gadolinium 3D-FLAIR techniques are sensitive to inner ear involvement associated with VS, the driving mechanism and their temporal relationships with labyrinthine signal intensity and hearing impairment remain unknown. ABBREVIATIONS AAO-HNS =American Academy of Otolaryngology -Head and Neck Surgery. BLB =blood-labyrinth barrier. CPA = cerebellopontine angle. IAC = internal auditory canal. PTA = pure tone average; SIR = signal intensity ratio. VS = vestibular schwannoma. WRS = word recognition score.