Characterisation of Cortical Vestibular Evoked Potentials (C-VEPs): A Comparative Study of Normal Ears Versus Those With Vestibular Deficits

The pathophysiology of vertigo is complex and usually requires specialist involvement. During the diagnostic process, patients commonly undergo tests which assess the integrity of the gaze and posture stabilisation mechanisms involving the inner ear (vestibular system), the visual systems and the subconscious neural pathways that interconnect them. Whilst these tests are useful they fail to provide information concerning the neural connections to the cortex and therefore neglect the perceptual aspects of disequilibrium.

At present the possibility of routine examination of these higher projections remains elusive as no practical alternatives to the expensive functional magnetic resonance imaging systems exist. However, recently a novel method of recording cortical vestibular evoked potentials (CVEPs) has been described.

CVEPs utilise an existing method used to interrogate cortical projections from the auditory system in which sound waves stimulate the inner ear and the resulting electrical responses from the brain are recorded. The recent breakthrough is in the realisation that these responses also contain information from the balance organs and therefore are a direct measure of cortical processing of the vestibular inputs.

Current evidence shows that CVEPs are present in the normal population and absent in patients with no vestibular function. The primary aim for this study is to extend the patient cohort to include those who have a vestibular injury but retain residual function. Patients going through standard testing will have also have CVEPs on both ears providing seminal information into the effect of injury to the peripheral vestibular system on the cortical pathways. Furthermore, by following the cohort through their complete management pathway it will be possible to ascertain if the CVEP can be used to predict rehabilitation outcome success.