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

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.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.The results showed no remarkably better synchronization with modified stimuli. Whereas higher levels showed no synchronization, reproducible positive waves at 8 ms (P8) at intensities of 65-85 dB were found in six patients with all stimuli.We suggest an ipsilateral auditory origin of the positive potentials at 8 ms. They could be characteristic of synchronization abnormalities in some cases of ANSD.