Identification of Neonatal Hearing Impairment: Hearing Status at 8 to 12 Months Corrected Age Using a Visual Reinforcement Audiometry Protocol

TLDR

This study is among the few to report 1‑year hearing status of at‑risk infants using VRA, and it is the largest effort to follow all at‑risk infants with behavioral audiometry to validate newborn screening tests. The study aimed to describe the hearing status of at‑risk infants at 8–12 mo corrected age and to detail the visual reinforcement audiometry protocol used for monaural behavioral testing. Monaural VRA thresholds at 1.0, 2.0, and 4.0 kHz were obtained with insert earphones, achieving >95 % reliability and 90 % complete testing across both ears. Of the 4,868 surviving infants, 3,134 (64.4 %) returned for VRA, 94 % had normal hearing, 2.2 % had bilateral impairment, 3.4 % unilateral, and over 95 % of those tested completed the protocol successfully.

Abstract

1) To describe the hearing status of the at-risk infants in the National Institutes of Health-Identification of Neonatal Hearing Impairment study sample at 8 to 12 mo corrected age (chronologic age adjusted for prematurity). 2) To describe the visual reinforcement audiometry (VRA) protocol that was used to obtain monaural behavioral data for the sample.All neonatal intensive care unit infants and well babies with risk factors (including well babies who failed neonatal tests) were targeted for follow-up behavioral evaluation once they had reached 8 mo corrected age. Three thousand one hundred and thirty-four (64.4%) of the 4868 surviving infants returned for at least one behavioral hearing evaluation, which employed a well-defined VRA protocol. VRA thresholds or minimum response levels (MRLs) were determined for speech and pure tones of 1.0, 2.0, and 4.0 kHz for each ear using insert earphones.More than 95% of the infants were reliably tested with the VRA protocol; 90% provided complete tests (four MRLs for both ears). Ninety-four percent of the at-risk infants were found to have normal hearing sensitivity (MRLs of 20 dB HL) at 1.0, 2.0, and 4.0 kHz in both ears. Of the infants, 2.2% had bilateral hearing impairment, and 3.4% had impairment in one ear only. More than 80% of the impaired ears had losses of mild-to-moderate degree.This may be the largest study to attempt to follow all at-risk infants with behavioral audiometric testing, regardless of screening outcome, in an effort to validate the results of auditory brain stem response, distortion product otoacoustic emission, and transient evoked otoacoustic emission testing in the newborn period. It is one of only a few studies to report hearing status of infants at 1 yr of age, using VRA on a clinical population. Successful testing of more than 95% of the infants who returned for the VRA follow-up documents the feasibility of obtaining monaural behavioral data in this population.