Exploring applications of electrically evoked compound action potentials using the vestibulo-cochlear implant

Area of Science:

• Neuroscience
• Biomedical Engineering
• Otolaryngology

Background:

• Vestibulo-cochlear implants offer a potential treatment for vestibular dysfunction.
• Objective outcome measures are crucial for assessing efficacy and optimizing these implants.
• Electrically evoked compound action potentials (eCAPs) are used in neural prosthetics to measure neural responses.

Purpose of the Study:

• To explore the utility of eCAPs in vestibulo-cochlear implant research.
• To determine if eCAPs can predict the electrically evoked vestibulo-ocular reflex (eVOR) and its misalignment.
• To assess eCAPs for auditory perception and cross-stimulation between cochlear and vestibular implants.

Main Methods:

• eCAPs were recorded in ten subjects with vestibulo-cochlear implants using various electrode configurations.
• The study evaluated the predictive value of eCAPs for eVOR presence, eVOR misalignment, auditory perception, and vestibular activation from cochlear stimulation.

Main Results:

• eCAPs showed a high positive predictive value (1.0) for eVOR presence but a low negative predictive value (0.54).
• Trans-canal eCAPs did not correlate with eVOR misalignment.
• Auditory perception prediction by eCAPs was low (≤0.5), and cochlear-to-vestibular stimulation was observed in 67% of electrodes.

Conclusions:

• Vestibular eCAPs predict eVOR presence but are unreliable for intra-operative electrode positioning due to low negative predictive value.
• Spread of excitation between cochlear and vestibular electrodes occurs within clinical fitting ranges.
• Further research is required to fully understand the potential of eCAP measurements in vestibulo-cochlear implants.