Congenital Hearing Loss and Internal Auditory Canal Anomalies: Imaging Findings and Implications for Management

Abstract

Objectives: Approximately 20% of patients with congenital sensorineural hearing loss are found to have a radiologically proven inner ear anomaly. Of the inner ear abnormalities, duplication of the internal auditory canal is rare. We sought to describe clinical characteristics and treatment results of patients found to have duplicated internal auditory canal on imaging. Methods: This case series identified patients from over a 2 year period obtained in a random manner from teaching files and daily case material. Imaging findings, clinical characteristics, audiology testing and treatment were reviewed. Results: A total of 7 patients were identified with a total of 12 ears (2 patients had unilateral presentation). Three patients in this series had a history of branchio-oto-renal syndrome. All patients had high-resolution computerized tomography (CT) performed. Two patients had magnetic resonance imaging (MRI) performed. All patients had audiogram evaluation. Six patients had sensorineural hearing loss, and one patient had conductive hearing loss. As hearing loss became more severe as documented by decibels of hearing loss on audiogram, increasing number of middle and inner ear anomalies were found on imaging. Conclusions: This series is one of the largest series to evaluate duplicated internal auditory canal in conjunction with cochlear anomalies. MRI is a useful adjunct to evaluate presence of the cochlear nerve and should be considered in patients undergoing cochlear implantation with findings of duplicated internal auditory canal on CT scan. More severe hearing loss may be indicative of potential for more anomalies found on imaging.