Vestibular Schwannoma–Related Increased Labyrinthine Postgadolinium 3D-FLAIR Signal Intensity and Association with Hearing Impairment

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 postgadolinium 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 postgadolinium MRI. Correlations with paired audiometric data, including pure tone average (PTA), word recognition score (WRS), and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing class within 1 year, were evaluated.

RESULTS: One hundred twenty-five studies obtained from 2015 to 2022 among 66 patients undergoing observational management for sporadic VS were analyzed. Increased signal intensity was noted in 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 = .03) and pontine comparisons (CC 0.24, P = .006), and with decreased WRS on pontine comparisons (CC –0.18, P = .04). Increased signal intensity was significantly associated with nonserviceable AAO-HNS C/D hearing when intensities were compared with the pons (P = .01) but not the contralateral labyrinth (P = .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 postgadolinium labyrinthine signal is associated with sensorineural hearing loss; however, its relationship with hearing trajectory remains unclear. Overall findings suggest that while postgadolinium 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.