A positive wave at 8ms (P8) and modified auditory brainstem responses measurement in auditory neuropathy spectrum disorder.

Schmidt CM, Huebner JR, Deuster D, Zehnhoff-Dinnesen AA, Knief A

Abstract

OBJECTIVE Auditory neuropathy spectrum disorder (ANSD) is characterized by absent or atypical auditory brainstem responses (ABR), recordable otoacoustic emissions and/or cochlear microphonics. Modification of ABR stimuli is discussed to improve wave V synchronization in ANSD patients. DESIGN Ten ANSD children (seven unilateral) underwent ABR measurement with an alternating stimulus (40.5s(-1)), constant rarefaction and condensation stimuli, a reduced click-rate (11.1s(-1)) and a chirp-stimulus. RESULTS The results showed no remarkably better synchronization with modified stimuli. Whereas higher levels showed no synchronization, reproducible positive waves at 8ms (P8) at intensities of 65-85dB were found in six patients with all stimuli. CONCLUSIONS We suggest an ipsilateral auditory origin of the positive potentials at 8ms. They could be characteristic of synchronization abnormalities in some cases of ANSD.