Evaluation of auditory pathway excitability using a pre-operative trans-tympanic electrically evoked auditory brainstem response under local anesthesia in cochlear implant candidates

Abstract

Objective

Subjective promontory stimulation is used to evaluate cochlear implant (CI) candidacy, but the test reliability is low. Electrically evoked auditory brainstem response (EABR) can verify the function of the auditory system objectively. This study’s procedure uses a trans-tympanic rounded bent-tip electrode to perform pre-operative EABR under local anaesthesia (LA-TT-EABR) using MED-EL Software and Hardware. This study aimed to determine usability and effectiveness for CI candidates.

Design

We hypothesised that LA-TT-EABR waveforms of good quality would be related to successful hearing outcomes. We assumed that the duration of hearing loss/deafness was a confounding factor to study outcomes.

Study sample

19 borderline CI candidates.

Results

Positive LA-TT-EABR results were confirmed in 14 patients. LA-TT-EABR’s mean latency was 2.05 ± 0.31 ms (eII/eIII) and 4.24 ± 0.39 ms (eIV/eV). Latencies weren’t statistically different from intra-operative EABR elicited by basal CI contacts. All positive LA-TT-EABR patients benefitted from CI and speech performance improved one year after implantation. One patient with negative LA-TT-EABR was cochlear-implanted and had no hearing sensation.

Conclusions

LA-TT-EABR is a tool in the frame of pre-operative objective testing the auditory pathway. It seems useful for clinical testing CI candidacy. Based on this study’s outcomes, LA-TT-EABR should be recommended for uncertain CI candidates.

Keywords:

• Promontory stimulation
• EABR
• LA-TT-EABR
• PromBERA
• PromStim
• cochlear implant
• auditory pathway

Acknowledgments

The work of DP, MN, JM, and JH was supported by the EABR project n. 412–13. The LA-TT-EABR measurements were performed in collaboration with MED-EL Medical Electronics. The authors would like to thank Una Doyle, MED-EL Medical Electronics, Translational Science Communication, for writing services on a version of this manuscript.

Informed consent

Informed consent was obtained from all individuals included in this study.

Ethics approval

The research related to human subjects complies with all relevant national regulations, institutional policies, and was performed following the Declaration of Helsinki and has been approved by the Ethics Commission of the faculty of Medicine, LMU Munich, Germany Project n. 412–13.

Disclosure statement

GM and MP are employed by MED-EL Medical Electronics, R & D. JH is a member of the surgery advisory board for MED-EL. DP, MN, and JH received travel expenses to conferences from MED-EL.

Additional information

Funding

Publishing was enabled and organised by the “EABR project” (project n. 412–3). Funding for the publication charges of this article were provided by MED-EL Medical Electronics.