The potential of electrocochleography in explaining the variability in cochlear implant outcomes: a scoping review

Abstract

Objective: This review aimed to catalogue the literature exploring electrocochleography (ECochG) as a potential tool to improve pre-implantation counselling for cochlear implant (CI) recipients. Specifically, it examined the correlation between ECochG responses and speech perception to assess whether these measurements could explain some of the variability in CI outcomes.

Design: Scoping review.

Study sample: Sixteen studies were included in this review, 14 of which investigated the correlation between ECochG total response (ECochG-TR) and speech perception outcomes. Additionally, four studies focused on specific components of ECochG-TR in relation to speech perception outcomes.

Results: Despite several limitations, most studies found that ECochG-TR significantly contributed to the variability in speech perception outcomes, explaining between 16-59% of the variance. The few studies correlating specific ECochG responses, such as cochlear microphonics, summating potential, auditory nerve neurophonics, and compound action potential, with CI outcomes, reported inconsistent results.

Conclusion: This review demonstrated that ECochG-TR can explain a significant portion of the variance in CI outcomes. However, due to the numerous limitations, further research is needed on the correlation between specific ECochG responses and CI outcomes. While ECochG measurements hold value in a research context, they have limited utility in clinical practice for pre-implantation counselling.

Keywords: Electrocochleography; clinical variability; cochlear implant; hearing outcomes; speech perception.