The SP-AP compound wave in patients with auditory neuropathy.

CONCLUSIONS

This study suggests that the asynchronization of the cochlear afferent pathway may be one mechanism of the etiopathogenesis of auditory neuropathy.

OBJECTIVE

To investigate the characteristics of the SP-AP compound wave and its generating mechanism in patients with auditory neuropathy.

SUBJECTS AND

METHODS

The electrocochleogram (ECochG) was recorded with external ear canal electrode in patients with auditory neuropathy and normal subjects. The peak-latency, amplitude, and time course of the SP-AP compound wave were measured by using an 'assessor-blind' study. The discrepancy between the two groups was evaluated by statistical analysis.

RESULTS

The SP-AP compound waveform in the auditory neuropathy patient group was unrepresentative. The transient character of the SP-AP compound wave was more atypical than that for the normal cases. SP dominance (-SP/AP>0.4) appeared. The amplitude of both AP and SP was lower than that of the control group. The width of the SP-AP compound wave at one-third of its peak was greater than that of the control group.