Inner Ear Enhancement With Delayed 3D-FLAIR MRI Imaging in Vestibular Schwannoma

Objectives: To evaluate blood–labyrinth barrier permeability using delayed gadolinium enhanced three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) in patients with untreated sporadic vestibular schwannoma (VS) to interrogate the etiopathogenesis of progressive sensorineural hearing loss. Design: Prospective case series. Setting: Single institution tertiary care center. Participants: Patients with previously untreated small to medium-sized unilateral VS undergoing 3D-FLAIR imaging 10 minutes (immediate) and 5 to 8 hours (delayed) after administration of intravenous gadolinium. Main Outcome Measures: Comparison of cochlear and vestibular signal intensity ratios (SIRs) across immediate and delayed images and across the tumor and nontumor ear. Results: Six of eight (75%) patients demonstrated asymmetric enhancement of inner ear structures on delayed contrast-enhanced imaging. Delayed mean cochlea and vestibule SIRs were significantly greater than immediate SIRs (cochlea: 1.91 versus 1.21 [ p = 0.02]; vestibule 1.74 versus 1.15 [ p = 0.02]). A higher vestibule SIR was statistically significantly associated with poorer pure-tone average and word recognition scores ( p = 0.001). Conclusion: Ears with VS exhibited increased enhancement on delayed 3D FLAIR imaging. These findings suggest that alterations in blood–labyrinth barrier permeability may explain progressive sensorineural hearing loss in a subset of patients with untreated VS.