INTRAOPERATIVE TEST OF AUDITORY-NERVE FUNCTION

Objective: To develop a preoperative objective test of auditory nerve function for the assessment of cochlear implant candidacy, especially in children. Patients and Methods: We stimulated electrically with a b all electrode before insertion of the implant. First the stimulus was applied bipolar between the promontory and the round window. To record auditory brain stem responses (EABRs) very high stimulus intensities were needed, which was not possible in all patients. Results: By stimu lation in the basal turn of the cochlea, evoked potentials could be de rived. Although in some patients the facial nerve was stimulated as a side effect, auditory evoked potentials could be recorded. A facial mu scle artifact can be differentiated from the EABRs by latency and the slope of the input-output function. Conclusion: For the present, the o nly reliable test seems to be the EABR recording stimulated within the cochlea.