The value of ABR- and ASSR-based hearing estimation in young children with congenital monaural malformation (atresia).

The electrophysiology of auditory nerve mature is particularly important for unilateral hearing loss. To assess the hearing status in young children with congenital monaural malformation and evaluate their potential for practical use in the functional maturation parameters of the auditory pathway. ABR (auditory brainstem responses) and ASSR (auditory steady-state responses) threshold measurements were performed in 21 young children with congenital monaural atresia. The average electrophysiologic thresholds for the ABR were 65 dB nHL ± 1.20 in malformed ears and 25 dB nHL ± 0.48 in normal ones. All 21 atretic ears presented with typical conductive hearing loss. There was no statistic positive correlation in hearing-impaired ears between the methods of ABR and ASSR responses ( = 0.12, 0.20 and 0.17). The IPL (interpeak latency) of I-III, III-V and I-V of atretic ears in ABR test was decreased relative to normal ears. Furthermore, a shortening of the IPLs I-III, III-V, I-V can be observed with increasing age of the children in malformed ears. The ABR- and ASSR-based hearing evaluation in young children with congenital monaural malformation should be viewed as complementary technologies. Besides, there was no delay of functional maturation at brainstem level although unilateral hearing was deprived during their early years of life.