Temporal Bone Abnormalities in Children with GJB2 Mutations

Objectives: To determine the incidence of temporal bone abnormalities in children with sensorineural hearing loss (SNHL) and pathogenic biallelic GJB2 mutations. Study Design: Retrospective analysis of a large cohort of pediatric patients with biallelic GJB2 mutations and SNHL (observational case series). Methods: Blinded review of all available temporal bone computed tomographic (CT) and magnetic resonance imaging (MRI) studies in this cohort. Results: Out of 158 patients with biallelic GJB2 mutations, 113 had CT and/or MRI studies available for review. Definite, although generally subtle, inner ear abnormalities were present in 12/113. There were malformations of the semicircular canals (SCC) in 4/12, of the internal auditory canal in 2/12, of the cochlear nerve canal (CNC) in 6, and unilateral cochlear malformation in 1/12. MRI in 1/5 showed mildly hypoplastic cochlear nerve. There was no correlation between SNHL severity and presence/absence/type of malformations or genotype. Conclusions: Our study of 113 biallelic GJB2 patients with SNHL and temporal bone imaging is the largest study to date. We found only 10% had any abnormalities, most subtle, and none had EVA. Additionally, there was no correlation between SNHL severity and presence/absence/type of malformations or genotype. Disparities between our group and previous reports may be due to differences in degree of hearing loss, types of mutations, populations studied, and radiologic factors for both image acquisition and interpretation.