Vestibular Response to Electrical Stimulation of the Otolith Organs. Implications in the Development of A Vestibular Implant for the Improvement of the Sensation of Gravitoinertial Accelerations

Abstract

OBJECTIVE:Electrical stimulation of the utricular and saccular portions of the vestibular nerve improves stability in patients suffering from vestibular dysfunction. The main objective of this study was to evaluate a new technique, vestibular response telemetry (VRT), for measuring the electrically evoked vestibular compound action potential (saccular and utricular) after stimulating the otolith organ (saccular and utricular) in adults. This study used evidence that the otolith organ can be electrically stimulated in order to develop a new vestibular implant design to improve the sensation of gravitoinertial acceleration. MATERIALS and METHODS:Four adult patients were evaluated by using a variety of measurement procedures with novel VRT software. VRT values were obtained by stimulating with three full-band Nucleus CI24RE (ST) electrodes. Specific stimuli were used. Simultaneously, electrical ocular vestibular evoked myogenic potentials (eoVEMPs) were recorded in the contralateral side. RESULTS:Electrically evoked compound action potentials were obtained in 10 of the 12 electrodes tested, and eoVEMPs were recorded when VRT was present. In addition to the validation of this technique, a set of default clinical test parameters was established. The VRT response morphology consisted of a biphasic waveform with an initial negative peak (N1) followed by a positive peak (P1), and latencies were typically 400 μs for N1 and 800 μs for P1. The consequences for the development of a vestibular implant for the improvement of gravitoinertial acceleration sensation are also presented. CONCLUSION:The VRT measurement technique has been shown to be a useful tool to record neural response on the otolith organ, and thus it is a convenient tool to evaluate whether the implanted electrodes provide a neural response or not. This can be used for the early development of vestibular implants to improve gravitoinertial acceleration sensation.

Binocular 3D otolith-ocular reflexes: responses of chinchillas to prosthetic electrical stimulation targeting the utricle and saccule

“…Recently, Ramos de Miguel et al (2017) reported initial attempts at utricular stimulation in humans. Three electrodes from a commercial cochlear implant were inserted temporarily in the vestibule near the utricle while attempts were made, with the patient under general anesthesia, to record far-field potentials the authors interpreted as electrically evoked compound action potentials from the electrode array and ocular vestibular evoked myogenic potentials (oVEMPs) for the contralateral eye.…”

Vestibular prosthesis: from basic research to clinics

“…The otoliths can also encode head rotations and contribute to angular VOR compensation ( Sadovnichy et al, 2007 ; Ramos de Miguel et al, 2017 ). However, the topographical organization of otolithic end-organs is complex.…”

“…A device derived from a Nucleus CI24M cochlear implant with bidirectional telemetry and with three active electrodes for vestibular stimulation, were implanted unilaterally in patients selected following Barany criteria for VI, with an absence of vestibular evoked myogenic potentials (VEMPs) and profound deafness ( Ramos de Miguel et al, 2017 ). Subjects were implanted with an extralabyrinthine electrode in the inferior vestibular nerve in a region mainly containing afferent neurons from the saccular macula and likely from the posterior SCC.…”

Multi-frequency VEMPs improve detection of present otolith responses in bilateral vestibulopathy

“…This is a (not yet clinically available) strategy to partially restore vestibular function by stimulating the vestibular nerves, using surgically implanted electrodes ( 21–23 ). The electrodes can be implanted inside or close to the semicircular canals ( 24 , 25 ), or inside the otolith organs ( 26 ). Surgically positioning electrodes in a semicircular canal or otolith organ, can destroy the (residual) function of that specific organ.…”