Elongated EABR wave latencies observed in patients with auditory neuropathy caused by mutation.

OBJECTIVES

We sought to determine how the pathology altered electrically evoked auditory brainstem responses (EABRs) in patients with hearing loss by evaluating EABRs in auditory neuropathy patients with mutations comparing with various types of congenital deafness.

METHODS

We included 15 patients with congenital hearing loss, grouped according to pathology: mutations (n = 4), mutations (n = 4), mutations (n = 4), or cytomegalovirus infections (n = 3). EABRs were recorded when patients underwent cochlear implantation surgery. We evaluated the latencies and amplitudes of the recorded EABRs and compared them statistically between four groups.

RESULTS

The EABR latencies of Wave III and Wave V, and of the interval between them, were significantly longer in the mutation group than in the and mutation groups (Wave III) and in all three other groups (Wave V and Wave III-V latency); amplitudes were not significantly different between groups.

CONCLUSIONS

Our results suggest mutations cause delayed (or slowed) postsynaptic neurotransmission, although the presumed mechanism involved reduced presynaptic transmission between hair cells and spiral ganglion neurons.

LEVEL OF EVIDENCE

Mainly a case report.