Relationship between electrically evoked auditory brainstem response and auditory performance after cochlear implant in patients with auditory neuropathy spectrum disorder.

OBJECTIVE: To analyze the pattern of electrically evoked auditory brainstem response (EABR) in auditory neuropathy spectrum disorder (ANSD) patients and to compare their performances with controls.

STUDY DESIGN: Retrospective analysis.

SETTING: Tertiary referral center.

PATIENTS: Eleven patients with ANSD and 9 control subjects with sensorineural hearing loss who did not have neural pathology.

INTERVENTION: Diagnostic.

MAIN OUTCOME MEASURES: Patients and control subjects each received a cochlear implant (CI) and underwent EABR. EABR threshold, wave V latency, and amplitude were measured as EABR parameters. The results of EABR were categorized as good response, variable response, or no response. Speech perception ability was assessed by the categories of auditory performance (CAP) score.

RESULTS: All controls responded to EABR, whereas 6 of the 11 ANSD patients did not respond to EABR. The EABR threshold of the ANSD patients was measured almost within the value of disease controls. However, the Wave V latency displayed variable lengths, and the amplitude showed a wider distribution compared with the value of the disease control. The EABR response group among the ANSD patients showed relatively good performance after CI. In contrast, the nonresponse group demonstrated variable outcomes, although all of them still benefited from CI.

CONCLUSION: The data suggested that all ANSD patients require CI and that EABR results can help establish realistic expectations about future performance. Even if electrical stimulation fails to generate sufficiently synchronized signal for eliciting EABR, CI provides at least partial, measurable auditory benefit in ANSD.