First-in-Human Trial of the MVI™ Multichannel Vestibular Implant in Individuals with Bilateral Sensorineural Vestibular Hypofunction: Effects on Posture and Gait

Background: Bilateral vestibular hypofunction (BVH) due to ototoxic hair-cell injury is disabling, with affected individuals suffering chronic oscillopsia, disequilibrium and postural imbalance. The Labyrinth Devices MVI™ Multichannel Vestibular Implant system is intended to treat chronic, adult-onset, severe-to-profound BVH in individuals who remain severely symptomatic despite vestibular rehabilitation. This system encodes head rotation information via motion-modulated pulsatile electrical stimulation of vestibular afferent nerve branches, mimicking normal semicircular canal function.

Objective: Investigating the efficacy of the MVI™ system on gait and postural balance.

Methods: Three subjects were implanted between 8.2016 to 2.2017, in the left ear. Subjects wore their MVI™ systems 24 hrs/day and were evaluated 1, 2, 3, 6, 8, ~20 and ~45 weeks after activation. Efficacy was evaluated by comparing performance on clinical and laboratory posture and gait tests while the MVI™ system delivered either motion-modulated or constant-rate stimulation (“baseline only”). We fit a general linear mixed-effect model to quantify outcomes as functions of subject, condition (modulation vs. baseline) and time.

Results: All subjects reported improvement in balance symptoms and activity level. Due to the small sample size, there was no statistically significant difference between conditions within all subjects; however, trends suggest improvement after adaptation to motion modulation signals. DGI score improved more than the clinical minimal detectable change (3.2 points) in two of the three patients. One subject exhibited a clinically significant increase in time to failure during a modified Romberg test with their eyes closed and standing on foam. TUG scores improved significantly for two of the three subjects (p<0.05). Gait pattern showed trends toward more stable walking. BOT score, gait speed, and stride length changes are inconclusive. Gait rhythmicity did not change.

Conclusions: These data demonstrate that motion-modulated prosthetic input from the MVI™ system provides sensory input that can improve gait and balance in subjects with BVH.