How differ eCAP types in cochlear implants users with and without inner ear malformations: amplitude growth function,...

Area of Science:

• Otolaryngology
• Neuroscience
• Biomedical Engineering

Background:

• Inner ear malformations (IEMs) can influence cochlear implant (CI) outcomes.
• Electrically evoked compound action potentials (eCAPs) are key objective measures in CI users.
• eCAP presence rates differ between CI users with and without IEMs.

Purpose of the Study:

• To evaluate eCAP results in CI users with and without IEMs.
• To compare different eCAP recording methods: amplitude growth function (AGF), spreads of excitation (SOE), and refractory recovery (RecF).
• To assess the impact of IEMs on eCAP presence, thresholds, and amplitudes.

Main Methods:

• Studied 42 CI users (20 with IEMs, 22 normal), aged over five years with at least one year of CI experience.
• Conducted three eCAP measurements (AGF, SOE, RecF) at multiple intracochlear electrodes.
• Compared eCAP presence rates, threshold levels, and amplitudes between the IEM and normal groups.

Main Results:

• A significant difference in eCAP threshold detection was found only at the basal electrode.
• No significant differences in AGF-eCAP and RecF-eCAP amplitudes were observed across apical, middle, and basal regions between groups.
• While SOE-eCAP presence was lower in the IEM group, eCAP amplitudes remained similar for all maskers.

Conclusions:

• Observable eCAP rates differ between CI users with and without IEMs.
• Despite differing presence rates, CI users with IEMs demonstrate eCAP amplitudes comparable to those with normal cochlear structures.
• IEMs may not significantly alter the neural response amplitude measured by eCAPs.