Systematic review of compound action potentials as predictors for cochlear implant performance

Area of Science:

• Neuroscience
• Audiology
• Biomedical Engineering

Background:

• Variability in cochlear implant (CI) user speech perception is linked to auditory nerve degeneration.
• Histological assessment of auditory nerve degeneration correlates with electrophysiological measures like electrically evoked compound action potentials (eCAPs) in animals.
• Predicting auditory nerve degeneration in humans requires non-invasive methods like analyzing eCAPs.

Purpose of the Study:

• To review the correlation between speech perception and eCAP recordings in cochlear implant patients.
• To assess the potential of eCAPs as a predictive measure for auditory nerve degeneration in humans.

Main Methods:

• Systematic literature search of PubMed and Embase databases.
• Inclusion of articles on cochlear implants, evoked potentials, and speech perception.
• Independent title-abstract screening, full-text review, and critical appraisal by two investigators.

Main Results:

• Twenty-five of 1,429 articles reported a correlation between speech perception and eCAP attributes.
• Significant correlations were found for eCAP presence, recovery time constant, slope of amplitude growth, and spatial selectivity.
• No significant correlations were observed for neural adaptation, eCAP threshold, or interphase gap effects.

Conclusions:

• While correlations exist between speech perception and eCAP parameters, reporting is often ambiguous.
• Current evidence is insufficient to establish eCAPs as a definitive predictive factor for speech perception in CI users.
• Further research is necessary to clarify the relationship between eCAPs and speech perception outcomes.