Auditory Brainstem Evoked Response: response patterns of full-term and premature infants

Auditory Brainstem Response (ABR) is important for the early diagnosis of hearing impairment in infants. AIM: To compare ABR responses in full-term and premature infants; gender and ear were taken into account. METHODS: A cross-sectional prospective cohort study was carried out. We evaluated 36 full-term and 30 premature infants that had passed the Transient Otoacoustic Emissions test, had type A tympanometric curves, and had no risk factor for hearing loss besides prematurity. The evaluations were done from the time of hospital discharge to the third month of life, and consisted of a clinical history, acoustic immittance testing and ABR evaluation. RESULTS: The comparison of absolute and interpeak wave I, III and V latencies in right and left ears revealed a statistically significant difference at the interpeak I-III. There was no significant gender differences in the comparison of results. Significant difference in wave I, III and V absolute latencies at 80 dB and in wave V at 60 db and 20 db were observed in a comparison of absolute and interpeak latencies between full-term and premature infants. An inverse correlation was found between age and absolute latencies. CONCLUSIONS: The maturity of the auditory system influences ABR responses in infants. To avoid misinterpretation of results, gestational age must be taken into account in the analysis of ABR in pediatric population.