Use of trans-tympanic electrically evoked auditory brainstem responses (TT-EABR) in decision making of cochlear implants in hypoplastic auditory nerve cases.

INTRODUCTION

Cochlear Nerve Deficiency, particularly Hypoplastic Auditory Nerve (HAN), creates uncertainty regarding Cochlear Implant (CI) outcomes. This study evaluated the utility of Transtympanic Electrically Evoked Auditory Brainstem Response (TT-EABR) in managing HAN cases.

METHODS

Twenty-two children with MRI-confirmed HAN were assessed using TT-EABR to guide ear selection for CI vs Auditory Brainstem Implantation (ABI) candidacy. Consequently, 13 children received CIs (HAN -CI group). Their auditory and speech outcomes -measured via CAP, SIR, and MAIS/IT-MAIS at baseline and 12 months post-implantation (with Auditory-Verbal Therapy) -were compared against an age-matched control group of 13 children with normal auditory nerves.

RESULTS

The HAN -CI group demonstrated significant improvements from baseline to 12 months in CAP (p=0.001), SIR (p=0.005), and MAIS/IT-MAIS (p=0.001) scores. Remarkably, no statistically significant differences were found between the HAN and control groups for CAP (p=0.93), SIR (p=0.70), and MAIS/IT-MAIS (p=0.97). Favorable outcomes correlated with Kumar-Dutt Type A and B TT-EABR responses, with Type A yielding the best results.

DISCUSSION &

CONCLUSION

While historical data associates HAN with poor outcomes, this study highlights that precise preoperative TT-EABR assessment and ear selection can lead to outcomes comparable to non-anomalous cases. TT-EABR is a pivotal prognostic tool, crucial for ear selection and managing parental expectations. Preoperative TT-EABR is essential for tailored clinical management and successful CI intervention in selected HAN cases.