Neonatal Auditory Brain Stem Responses from Ipsilateral and Contralateral Recording Montages

Abstract

Ipsilateral and contralateral auditory brain stem responses were recorded from both ears of 10 neonates between 37 and 43 weeks from conception with normal auditory brain stem function. The most prominent component of the contralateral response was a forehead positive deflection occurring 0.3 millisecond before the ipsilateral wave III followed by two forehead negative waves, the latter present at the same latency as the ipsilateral wave V. The amplitude of the contralateral response was small: at 30 dB nHL only 7 of the 20 ears showed clear responses from this montage. The morphology of the neonatal contralateral response is thus considerably different than the ipsilateral, unlike the adult. A neonate could be mistakenly diagnosed as hearing impaired or neurologically involved if the interpretation is based on the contralateral recording.