Clinical characteristics of children with cochlear nerve dysplasias

Abstract

To describe the clinical and audiometric characteristics of children with cochlear nerve dysplasia (CND). Retrospective chart review of clinical database of children with inner ear anomalies treated at a tertiary care children's hospital. Institutional review board-approved retrospective review from June 30, 2006, to July 1, 2011; 18 children were identified with magnetic resonance imaging (MRI) evidence of CND defined as a cochlear nerve 50% smaller than the adjacent facial nerve. Of the 18 patients, nine were girls and nine were boys. Average age at time of MRI diagnosis of CND was 4.6 years. Twelve children had cochlear nerve aplasia, and six had hypoplasia. Three were affected bilaterally: two with aplasia and one with hypoplasia. Unilateral dysplasia was found in 15 children; of these, 60% occurred on the left side. Other inner ear anomalies were found in 50%, including all patients with bilateral CND. Severe-to-profound hearing loss was found in the involved ear(s) in 14 of 18 patients, including all bilateral patients. Of the 18 patients tested, 13 (72%) had an audiometric profile of auditory neuropathy/dys-synchrony syndrome (auditory neuropathy spectrum disorder [ANSD]). Comorbid conditions were present in 56% of patients. Two patients were syndromic. Family history of hearing loss was present in 11% of patients. Many patients with CND have ANSD, and more than half have comorbidities. Approximately half of affected patients have other inner ear anomalies in the involved ears. Unilateral CND may be more common on the left side.