Newborn hearing screening and strategy for early detection of hearing loss in infants

Abstract

More than 80% of permanent hearing losses (HL) in children are congenital. Newborn hearing screening (NHS) is the best method for early detection of suspected hearing loss. If the NHS is not universal more than 30% permanent hearing losses are not identified. There are various methods of NHS: otoacoustic emissions (TEOAE, DPOAE) and automatic auditory brainstem response (AABR). After hearing screening, and when hearing loss is suspected, tympanometry and audiological methods then used for determination of hearing threshold; these include ABR, ASSR or/and behavioral methods. The goal of this study is to evaluate the influence of UNHS on the early detection of hearing loss in children before and after the implementation of obligatory universal newborn hearing screening in Slovakia, and also on the etiologic evaluation of hearing impaired infants identified by screening. In Slovakia NHS started in 1998 and was provided in ENT departments. From May 1, 2006 UNHS has been mandatory in Slovakia, using two stages TEOAE in all newborn departments in Slovakia (64 newborn departments). In year 2005--42% of newborns in Slovakia were screened, in 2006--66% newborns and in 2007--94, 99% (three small newborn departments do not yet have equipment for OAE screening). For determination of hearing thresholds ASSR are used in two ENT departments and ABR in the other four ENT departments. Comparing the number of identified cases with bilateral severe permanent HL or deafness before and after UNHS, 22.8% more cases of PHL were identified in the first year of UNHS. Also the average age of diagnosis of PHL was lower. In the year 2007, 94% of newborns were screened. We found 0.947/1000 newborns with bilateral severe PHL (35.9%) more than before UNHS). After audiologic and etiologic assessment of the 76 infants who failed screening, 5 (6.58%) were found to have normal hearing, 16 (22.54%) had unilateral and 55 (77.46%) had bilateral SNHL. A non-syndromic genetic cause was present in 25.45% of cases, syndromic in 9%, perinatal cause (31%), congenital CMV infection in 7.27%, bilateral cochlear anomalies without other abnormality in 1.83% and unknown etiology in 25.45%.