Vestibular ECAPs: Is their Presence Diagnosis-Dependent?

Background: Vestibular ECAPs have now been recorded in both human and non-human primate by at least three investigative teams. They can potentially be used to optimally position intralabyrinthine electrode arrays. They have been recorded in monkeys with both normal ears and acute and chronic aminoglycoside lesions as well as humans with Meniere’s disease, aminoglycoside ototoxicity, and sudden hearing and vestibular loss.

Objective: To determine if vestibular ECAP recordings differ across differing diagnoses.

Methods: Using the Nucleus NRT system, ECAPs have been recorded in four human subjects with Meniere’s disease, and one with sudden hearing and vestibular loss.

Results: ECAPs could be recorded from all semicircular canals implanted in Meniere’s patients for at least several months after surgery. All responses declined over time with some fluctuation in amplitude. In our subject with sudden hearing and vestibular loss ten years prior to surgery, no vestibular ECAP could be recorded from any of the canals despite a normal cochlear ECAP and CT documentation of appropriate vestibular array placement.

Conclusion: Unlike cochlear ECAPs, the presence of vestibular ECAPs may be diagnosis-dependent. Implications for further development of the vestibular implant will be discussed.

(Supported by NIDCD and Cochlear, Ltd)