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. Study Design: Prospective clinical study from January 2005 to August 2008. Setting: Cochlear Implant Program at the Charite University Hospital (Berlin, Germany). Patients: One hundred twenty-one patients with severe to total bilateral sensorineural hearing impairment. Intervention: Diagnostic. Main Outcome Measures: 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 producedclear 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. Conclusion: 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.