Vestibular implant stimulation can improve self-motion perception

IntroductionPatients with bilateral vestibulopathy (BV) typically suffer from a range of symptoms like oscillopsia, unsteadiness and impaired spatial orientation. This orientation is related to the perception of self-motion. Elevated perceptual self-motion thresholds were previously reported in BV patients. This proof-of-concept study evaluated the effect of multi-canal vestibular implant stimulation on perceptual self-motion thresholds.MethodsNine BV patients were implanted with an investigational intralabyrinthine multi-canal vestibulo-cochlear implant (VCI). Eight self-motion perception test sessions were performed, in order to compare three stimulation conditions: VI OFF, VI ON with symmetric modulation and VI ON with asymmetric modulation. A hydraulic platform was used to rotate the patient to measure the perceptual self-motion thresholds for yaw rotations. Rotations towards the implanted side were considered as excitatory stimulations, while rotations away from the implanted side were considered inhibitory stimulations.ResultsA significant improvement in perceptual self-motion thresholds was found during VI stimulation compared to no VI stimulation, when excitatory yaw rotations were applied. This improvement was present during both VI ON symmetric and asymmetric modulation. In contrast, no significant improvement in perceptual self-motion threshold was measured during inhibitory yaw rotations. However, a trend towards improved perceptual thresholds in inhibitory yaw rotations was observed with symmetric modulation.DiscussionThe vestibular implant offers potential in improving direction specific self-motion perception for yaw rotations in patients with BV. Consistent with previous findings in vestibular implant research, such as improvements in VOR gain, the effects of excitatory stimulation appear to be more pronounced than those of inhibitory stimulation.