INVESTIGATION OF HEARING IMPAIRMENT IN POST–NEONATAL INTENSIVE CARE UNIT INFANTS BY USING AUTOMATED AUDITORY BRAINSTEM RESPONSE

Abstract

INTRODUCTION: Hearing impairment affects 2% to 4% of NICU graduates and is associated with several risk indicators. OBJECTIVE: Our goal was to investigate the prevalence of hearing impairment in newborns hospitalized in an NICU and its association with risk indicators. METHODS: Subjects consisted of 422 post-NICU infants who fulfilled 34 weeks of gestational age and were examined between March 2005 and December 2006. The following parameters were evaluated: perinatal asphyxia, craniofacial deformities, furosemide and aminoglycoside therapy (duration of administration), meningitis, duration of mechanical ventilation, and nursing duration in an incubator. Screening was performed with the last-generation automated auditory brainstem response (AABR) equipment, ALGO 3 (Natus Medical Inc, San Carlos, CA). RESULTS: Results were considered normal when the newborn showed response to a 35-dBNA signal bilaterally. Newborns with hearing impairment were referred for early intervention. Multivariate analysis with logistic regression was used to identify the independent risk factors for hearing disturbances. The prevalence of AABR impairment was 2.84% (12 of 422 newborns); the impairment was unilateral in 7 of the infants and bilateral in 5 of them. These 12 infants were examined with conventional ABR with the following results: 6 of them showed normal responses, and in the other 6 infants the pathologic result was confirmed. Multivariate analysis revealed a statistically significant association between hearing loss and craniofacial deformities, meningitis, and duration of mechanical ventilation (P < .001, P = .001, and P = .038, respectively). CONCLUSIONS: Although the study sample was limited, the hearing-loss rate that we found was in accordance with that reported in the literature. The prevalence of hearing impairment found when using AABR is high. The only risk factors directly associated with hearing impairment proved to be craniofacial deformities, meningitis, and duration of mechanical ventilation.