Extending Electrical Vestibular Stimulation from basic science to clinical use.

Electrical Vestibular Stimulation is a simple method for stimulating the vestibular system and evoking sensations of movement. It has predominantly been used as a basic research tool, typically for studying postural control during standing or walking. However, it has long been observed that patients with vestibular loss exhibit altered responses to GVS, suggesting diagnostic potential. However, progression to clinic has been slow. This is largely due to practical issues, but also limitations of our knowledge regarding the stimulus mechanism. Here I will present some recent studies using non-invasive assessment of the  EVS-evoked vestibular-ocular reflex in healthy persons, as well as patients with Vestibular Schwannoma and complete unilateral vestibular loss. These studies show that EVS compares well to established tests (e.g. caloric irrigation) in terms of diagnostic capability, while offering greater convenience and practicality. Nevertheless, there remain significant questions regarding precisely which pathologies to which this technique can be applied. These questions will be answered by a combination of further empirical observations in vestibular patients, along with a better understanding of the basic stimulus mechanism.