Relationship Between Post-Operative Electrically Evoked Auditory Brainstem Response in Cochlear Implant Children With Inner Ear Anomalies and their Auditory Outcomes

Background:

Electrical stimulation of the cochlea can effectively activate the central auditory pathway, provide auditory perception and enable development of speech perception skills. Electrical stimulation from the cochlear implant evokes activity in the auditory brainstem, which can be measured as EABR waveform.

Aim: To investigate relationship between Vth peak of the post-operative electrically evoked auditory brainstem response (EABR) and auditory outcomes in cochlear implant (CI) children with inner ear anomalies.

Method: subjects were categorized into 2 groups, Group A included 11 CI children with inner ear anomalies of implant age 1 year and chronological age 2-6 years. Group B included age matched 11 CI children with only sensorineural hearing loss. At the implant age of 1 year for all the subjects post-operative eABR were recorded, auditory out-comes were measured using aided audiogram, CAP (categories of auditory perception) score and MAIS (meaningful auditory integrated scale).

Results: Normal auditory nerve group had EABR in all 3 electrodes i.e in apical, medial and basal positions. But in hypoplastic nerve group, 9 had EABR present and 2 did not have eABR. Out of 9, it was mostly present at apical region followed by medial and least in basal electrode.

EABR threshold and aided thresholds were better in subjects with normal auditory nerve group than hypoplastic nerve group. CAP and IT MAIS score was more in normal auditory nerve group than hypoplstic nerve.

Conclusion:-Post operative EABR can be used as a tool to establish realistic expectation for future performance.