Early cochlear implantation: exploring electrophysiological thresholds and their role in pre-behavioural recommendations.

Abstract

Background and aims: Studies investigating the relationship between initial electrophysiological thresholds and subsequent behavioural hearing thresholds have demonstrated uncertainty as to whether initial results can provide an accurate estimation of an infant's functional hearing. This estimation must be accurate if a cochlear implant (CI) is to be considered before behavioural audiometry.This study aims to explore the variance between initial electrophysiological thresholds and subsequent behavioural hearing thresholds in infants to determine under which conditions electrophysiological results can be used to support a CI recommendation before behavioural audiology.

Methods: This is a prospective cohort study of 63 infants with suspected severe to profound hearing loss, referred to the Cochlear Implant Clinic, Melbourne, before 12 months of age. The assessment protocol includes auditory brainstem response, auditory steady state response, tympanometry, and behavioural audiometry.

Conclusion: For most infants undergoing CI candidacy evaluation, initial electrophysiological thresholds are an accurate reflection of their subsequent behavioural thresholds. An alternative CI candidacy pathway is recommended for infants who show profound sensorineural hearing loss on initial electrophysiological testing, in the absence of middle ear effusion, prematurity, or auditory neuropathy features, to provide CI recommendations before behavioural thresholds are obtained. This would lead to reduced delay to implantation and improved oral language outcomes.