The Vertigo! trial: Evaluating the efficacy and safety of chronic daily stimulation in a multichannel vestibulo-cochlear implant (VCI) implant prototype

The vestibular organ is an integral sensory systems designed to provide afferent information to the brain. Once integrated, efferent signals are transmitted to produce a motor output associated with gaze stabilization through compensatory eye movements, postural adjustments, and maintenance of static and dynamic balance. A bilateral reduction or absence of vestibular function is classified as bilateral vestibulopathy (BV). Patients typically experience a multitude of symptoms, consequently resulting in a significant reduction in quality of life. Currently, no effective treatment is available. The Geneva-Maastricht group is investigating a combined multichannel vestibulo-cochlear implant (VCI). This VCI aims to partially restore vestibular function in patients suffering from BV. This study evaluates the effectiveness of multichannel VCI stimulation and modulation in enhancing vestibular perception and reduction of BV symptoms by improving vestibulo-ocular reflexes (VOR). Nine cases with BV and ipsilateral severe sensorineural hearing loss were implanted with the newest VCI prototype. After standard CI rehabilitation, the vestibular electrodes were fitted and activated. The effect of VCI stimulation on vestibular perception and VOR was evaluated. For an extensive protocol, please refer to doi.org/10.1371/journal.pone.0301032. VCI fitting and initial activation improved VOR, reduced oscillopsia, provided stable hearing performance (minimal CI-VI interference), and evoked perception and eye movements that are well-aligned (i.e. Ewald’s law). In addition, it was found that modulation is important in comparison to baseline-only stimulation. Preliminary VCI modulation results demonstrated promising outcomes and a proof of concept. Long-term home-use stimulation is needed to demonstrate the potential effect of chronic VCI modulation on daily living.