Evaluation of a novel, noninvasive, objective test of auditory nerve function in cochlear implant candidates.

Objective: To investigate whether the objective noninvasive recording of the electrically evoked amplitude modulation following response (EAMFR) can be applied for the assessment of auditory nerve function before cochlear implant surgery.

Methods: Prospective clinical study from January 2005 to August 2008. Methods: Cochlear Implant Program at the Charité University Hospital (Berlin, Germany). Methods: One hundred twenty-one patients with severe to total bilateral sensorineural hearing impairment. Methods: Diagnostic. Methods: All EAMFR thresholds were correlated with the mean intraoperative electrically evoked compound action potential (ECAP) thresholds. In a subgroup of 16 patients, the objective thresholds of the EAMFR were compared with the subjective auditory thresholds for the electrical stimuli applied. The intraindividual left-right concordance of the EAMFR and ECAP thresholds was investigated in 22 patients with bilateral implants.

Results: The EAMFR-auditory nerve function test produced clear responses in all patients examined. The threshold of auditory perception for the applied stimuli correlated highly significantly with the EAMFR threshold (r = 0.89, p < 0.01). The correlation between the EAMFR and mean ECAP thresholds was again highly significant (r = 0.49, p < 0.01). In all patients with bilateral implants, the ear with the lower preoperative EAMFR threshold was also the one with the lower intraoperative mean ECAP threshold.

Conclusions: These results indicate that the objective noninvasive recording of EAMFR seems to be a useful diagnostic tool for the evaluation of the auditory nerve function in cochlear implant candidates, especially in children or in adult patients who require objective examination.