Screening for Hearing Impairment in High Risk Neonates: A Hospital Based Study.

Abstract

Hearing loss very early in life can have multiple deleterious effects on the new born most commonly being related to attainment of speech and language. Also, it can affect social, emotional and academic achievement of the child.Early identification of hearing impairment has been shown to improve prognosis and hence screening programs have been widely and strongly advocated. To estimate the incidence of neonatal hearing loss in high risk neonates admitted in tertiary level teaching hospital and to determine the risk factors predictive of hearing impairment in them. It was a prospective study over a period of one year. We screened high risk neonates for hearing impairment admitted to NICU using Brain stem Auditory Evoked Response (BAER).The morphology of the response and wave and interwave latencies was examined in respect to age-appropriate forms. Follow up BAER after one month was performed in cases where initial BAER was abnormal. Babies who tested abnormal on the follow-up were referred for detailed audiology diagnostic work up. A total of 200 cases comprising 118 males (59%) and 82 females (41%) were enrolled. On initial BAER testing, 18 (15.25%) males and 14 (17%) female neonates had hearing loss. Whereas 7 males (70%) and 3 females (30%) had hearing loss out of the total 10 hearing loss cases in the Follow up-BAER testing. Two out of the 6 neonates with birth weight <1500g had hearing loss in the follow up of BAER testing. Use of ototoxic medications, hyperbilirubinemia requiring exchange transfusion, perinatal asphyxia and bacterial meningitis were the major risk factors occurring in 45%, 30% and 26% and 10%. Five neonates had unilateral hearing loss and the rest five (5%) had bilateral impairment.Meningitis was the significant independent clinical risk factors for predicting hearing impairment in high risk neonates.The risk of BAER increased cumulatively with BAER abnormality rate of 4.2%, 22.2% and 33.3% with one two and three risk factors respectively. The overall incidence of hearing loss in initial BERA testing was 16%, in males it was 15.25% in males and in 17% in females,only 62.5% of neonates had a persistent abnormal BAER, with male gender a significant risk factor for this. The incidence of hearing loss increased with number of risk factors. The study highlights that although universal hearing screening programs are warranted; most newborns with a detected hearing loss can be identified based on the risk factors. Thus, a targeted approach for hearing screening may be more feasible in resource limited settings.