Cochlear nerve hypoplasia identified years after passing newborn hearing screen

Abstract

Universal Newborn Hearing Screening (NHS) has been a mainstay of immediate post-partum care in the United States since the National Institutes of Health (NIH) released its recommendation for screening in the 1993 Consensus Conference Report.We present the case of a four-year-old female who had passed in-hospital NHS with transient evoked otoacoustic emission (TEOAE) bilaterally, yet presented four years later to the otolaryngology clinic with parental complaints of hearing dysfunction. Audiology evaluation demonstrated profound unilateral sensorineural hearing loss (SNHL) with absent TEOAE. Magnetic resonance imaging (MRI) revealed either absent or severely hypoplastic vestibulocochlear nerve (VCN) on the affected side.This case raises the possibility of initial preservation of outer hair cell function despite cochlear nerve aplasia or deficiency, as evidenced by the presence of TEOAE on NHS. The finding of reduced TEOAE 4 years after initially passing NHS suggests a progression from isolated VCN abnormality to dysfunction of the outer hair cells.