Analysis of the Anterior Inferior Cerebellar Artery Vascular Loop Using 3D Fast Imaging Employing Steady State Acquisition in Idiopathic Sensorineural Hearing Loss

- Background and Objectives Compression of the vestibulocochlear nerve by the anterior inferior cerebellar artery (AICA) vascular loop or impaired vascular flow of the cochlea can cause idiopathic sensorineural hearing loss. We have analyzed the correlation between position and diameter of the AICA vascular loop, and hearing loss at various frequencies. - Subjects and Methods 453 patients (906 ears) were included in this study. All patients underwent 3D-fast imaging employing steady state acquisition (FIESTA) MRI and pure tone audiometry. We have analyzed the average hearing level in average of six frequencies range (500, 1 k, 2 k, 3 k, 4 k, and 6 kHz), low frequency range (250, 500 Hz), mid frequency range (1 k, 2 kHz) and high frequency range (4 k, 6 k, 8 kHz). The ears were classified into a hearing loss group and a normal hearing group. We evaluated the position and diameter of the AICA vascular loop in 3D-FIESTA MRI by two scoring systems. The first scoring system was Chavda classification based on the anatomical location of the AICA loop. The second scoring system was used to measure the diameter of the AICA loop. The AICA loops were classified into two groups by diameter, small or similar to the adjacent facial nerve and larger than the facial nerve. - Results There was no statistically significant correlation between AICA loop location and hearing loss. There was no statistically significant correlation between AICA loop diameter and hearing loss in average PTA, mid tone, or high tone hearing. However, in low tone hearing, the diameter of the AICA loop in the hearing loss ear was significantly smaller than that of the AICA loop in the normal hearing ear. - Conclusions There was no correlation between vascular loop position and hearing loss found in this study. The diameter of the vascular loop could be the causative factor of idiopathic hearing loss