Auditory neuropathy: clinical characteristics and therapeutic approach

Abstract 

Purpose

Auditory neuropathy is characterized by congenital sensorineural hearing loss associated with absent or impaired auditory brainstem evoked responses and preservation of outer hair cell activity. This study describes the recent experience of our tertiary pediatric center with auditory neuropathy (AN).

Methods

The files of all children diagnosed with AN at our center from 2000 to 2005 were reviewed for background data, associated factors, laboratory and audiometry findings, management, and outcome.

Results

Mean age at diagnosis was 13 months. Factors known to be associated with AN were found in 18 children, namely, prematurity, hyperbilirubinemia, parental consanguinity, or positive family history. Conception by in vitro fertilization was an additional factor not previously reported. The hearing loss was mostly moderate to severe, and bilateral in all patients but one. Otoacoustic emissions and/or cochlear microphonics were demonstrated in all cases. Hearing improved spontaneously in 4 patients. Management with a hearing aid was successful in 1 of 19 patients. Twelve patients received cochlear implants with good outcome.

Conclusion

Because neonates with AN have normal otoacoustic emissions and/or cochlear microphonics, screening tests for high-risk neonates should be complemented by auditory brainstem evoked responses to avoid false-negative findings. Because AN is considered a retrocochlear lesion, with normal outer hair cell function, rehabilitation with hearing aids is problematic. Although the level of pathology is apparently at the cochlear nerve, cochlear implantation is often a good solution for failures of conventional rehabilitation. However, our finding of spontaneous improvement in a small subgroup raises questions regarding implantation before age 1 year.