Advances in early detection of hearing loss in infants

Abstract

Hearing Loss and the Register'Approach to Detection Recently, the National Institutes of Health convened a conference to provide a consensus on the importance of early detection of hearing loss, 1 the consequences of late identification, methods for early diagnosis, and directions for future study and research. Among the panel's recommendations were that infants in neonatal intensive care units be screened for hearing loss before discharge from the unit and that all infants be screened in the first 3 months of life. The recommendation for universal screening of hearing was based on the clear deleterious effects of undetected hearing loss on language acquisition, academic achievement, and social/emotional development. The prevalence of childhood hearing disability is estimated at 1.5 per 1000, with a range of 0.8 to 2 per 1000, 2 but universal screening currently remains a goal that is realized in only a few areas of the United States. When hearing screening for infants is available, it is usually limited to infants designated at risk for hearing impairment. Risk criteria were developed by the Joint Committee on Infant Hearing, 3 a consortium of agencies concerned with infant hearing and development. Currently, approximately 9% to 10% of newborns meet one or more of the risk criteria set forth by the committee. Risk is determined by chart review for one or more of the following factors: (1) family history of congenital or delayed onset of sensorineural hearing impairment; (2) congenital infection known to be, or suspected of being, associated with hearing impairment (toxoplasmosis, syphilis, rubella, cytomegalovirus [CMV] and Herpesvirus); (3) craniofacial abnormalities, especially of the pinna and ear canal; (4) birth weight less than 1500 gm; (5) hyperbilirubinemia at a level exceeding indication for exchange transfusion; (6) high levels of ototoxic drugs; (7) bacterial meningitis; (8) prolonged mechanical ventilation such as that associated with persistent pulmonary hypertension; (9) severe depression at birth with Apgar scores less than 4 at 5 minutes, lack of spontaneous respiration by 10 minutes, or persistent hypotonia up to 2 hours after birth; (10) stigmata or other findings associated with syndromes that include sensorineural hearing loss (e.g., Waardenburg or Crouzon syndromes). It is generally acknowledged that approximately 50% of the cases of hearing impairment are found among this pool of high-risk infants. Thus the risk register is an extremely effective tool for increasing the yield of hearing impairment detection while reducing the need for extensive testing of larger populations. High-risk infants are currently tested in one of two ways. Most infants undergo auditory brain stem response (ABR) testing in the neonatal intensive care unit