Latency of auditory nerve response in neonates one to eight hours old.

Recording the response of the auditory nerve (W1) in neonates can contribute to the diagnostic distinction between audiological-otological versus neurological pathology. If W1 latency were subject to relatively rapid shortening in the hours directly after birth, inconsistencies in the literature might be clarified. The purpose of this research was to study W1 in neonates one to eight hours old in order to determine if significant latency changes occur during this period. Auditory nerve-brainstem responses were recorded in 40 full-term neonates and in 12 normal adults. W1 latency in 1- to 3-hour-old neonates was 1.81 +/- 0.28 ms and 1.77 +/- 0.18 ms in 7- to 8-hour-old neonates. This difference was not significant. In adults, W1 latency was significantly shorter (1.36 +/- 0.06 ms). These findings indicate that auditory nerve latency is about 0.43 ms longer at birth than in the adult and that the latency does not shorten significantly during the first hours after birth.