Cochlear nerve deficiency in children with CHARGE syndrome

Abstract

To describe cochlear nerve deficiency and abnormalities of the internal auditory canal (IAC) associated with CHARGE (coloboma, heart defects, atresia choanae, retardation of growth and/or development, genital hypoplasia, and ear anomalies and/or deafness) syndrome. Case series. In a tertiary children's hospital, children with CHARGE syndrome were evaluated between 2006 and 2009. Morphology of the inner ear, IAC, and cochlear nerves was evaluated along with auditory-evoked brainstem response results. Of the 17 patients with CHARGE diagnosis, 14 ears demonstrated profound sensorineural hearing loss (SNHL). The remaining ears had conductive hearing loss, mixed hearing loss, or mild to moderate SNHL. Computed tomography (CT) evaluation was refused in one case and delayed in one case due to parental decision. Of 30 ears evaluated with CT, 28 (93%) had substantial abnormalities of the inner ear including hypoplasia or aplasia of the semicircular canals and abnormalities of the cochlea and vestibule. CT evaluation revealed cochlear aperture narrowing or occlusion in 16 ears, one of which had normal hearing. The eight most recent patients with profound SNHL (six bilateral SNHL, two unilateral) underwent magnetic resonance imaging (MRI) of the IAC, and 13 of 14 ears with SNHL were noted to have absent or deficient cochlear nerves. CT scans in two ears with profound SNHL revealed normal cochlear apertures. The dysmorphic inner ear is well described in CHARGE patients; however, cochlear nerve deficiency has not been considered a common etiology for SNHL in these patients. Because of the implications of cochlear nerve deficiency in therapeutic decision making (i.e., cochlear implantation), MRI evaluation of the eighth nerve should be considered in CHARGE patients with profound SNHL.