Screening for Hearing Impairment in High-Risk Neonates in a Tertiary Care Centre in Central Kerala

Author(s): J. Maina1 , Rati Santhakumar2 , V.C. Manoj3 , Mridula Vellore4

BACKGROUND Hearing loss is a chronic condition, and many cases can be detected in the neonatal period. Recognizing it early is of crucial importance as early auditory rehabilitation would help in child’s comprehensive development. We wanted to assess the prevalence of hearing impairment among high risk newborns admitted to inborn unit of tertiary care centre in Central Kerala and screen for the associated risk factors in these newborns. METHODS Thousand consecutive inborn neonates from Neonatal ICU, Department of Paediatrics, tertiary care centre in Thrissur, Kerala, detected as high risk by Joint Committee on Infant Hearing (JCIH) criteria were enrolled for the study from December 2011 to November 2012 after the approval by Institute’s Ethics Review Board. Risk factor assessment was done before enrolment. A qualified audiologist conducted the test on babies in soundproof chamber. DPOAEs (Distortion Product Otoacoustic Emissions) were used for initial testing after checking ears for debris. Those who failed in the first test were asked to come for a retest after 2 weeks. Those who failed in the retest were asked to report for Brainstem Evoked Response Audiometry (BERA). Those who were diagnosed as having hearing impairment were advised auditory rehabilitation as well as auditory verbal therapy. RESULTS Of the 1000 eligible neonates born in our hospital during the study period (December 2011 to November 2012) 69 were lost to follow up. Among the remaining 931 babies the frequency of hearing impairment was 0.8 %. Among the 931 neonates, 130 had absent response with the first OAE test contributing to 13.9 %. Twenty-one neonates had absent response to second OAE test out of 130 contributing to 16.1 %. The failure rate for second test is 2.2 % of the total population of 931 newborns. Eight of the 21 neonates who were subjected to BERA had severe hearing loss. The prevalence of hearing impairment was 8 per 1000. CONCLUSIONS The prevalence (percentage) of hearing impairment by two staged screening protocol is 0.8 %. Risk factors which were present in these babies were prematurity, low birth weight, low Apgar score, history of exanthematous fever in mother, neonatal jaundice, ototoxic medication history, craniofacial anomalies, and family history of deafness, meningitis and mechanical ventilation.