Temporal enhancement patterns on 3D-FLAIR MRI in labyrinthine infarction

Inner ear enhancement on contrast-enhanced three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) MRI reflects disruption of the blood-labyrinth barrier (BLB) and has been reported in several audiovestibular disorders. However, the temporal enhancement pattern in labyrinthine infarction remains poorly characterized.

We investigated time-dependent enhancement patterns on 3D-FLAIR MRI in four patients with labyrinthine infarction secondary to anterior inferior cerebellar artery infarction. All patients underwent comprehensive neuro-otological evaluation and contrast-enhanced inner ear MRI. Axial 3D-FLAIR images were obtained at three time points: pre-contrast, 10 min, and 4 h after gadolinium administration. Enhancement patterns were compared with those observed in 37 patients with non-vascular audiovestibular disorders, including sudden sensorineural hearing loss with vertigo ( n = 3), Ménière's disease (n = 9), recurrent vestibulopathy (n = 14), acute unilateral vestibulopathy (n = 11), who underwent the same imaging protocol.

All four patients with labyrinthine infarction demonstrated ipsilesional enhancement of both the cochlea and vestibule on 4-hour delayed images. Two patients also showed early enhancement confined to the cochlea on 10-minute images. By contrast, only 8 of 37 patients (22%) with non-vascular audiovestibular disorders demonstrated enhancement, which was predominantly observed on 4-hour delayed images but not detected on 10-minute images.

These findings suggest that 4-hour delayed enhancement is a consistent imaging feature of labyrinthine infarction, whereas early (10-minute) enhancement may occur in a subset of patients and may provide insight into the temporal evolution of BLB disruption following ischemic injury.