Vestibular evoked responses: a new frontier in equilibriometry

Abstract

Modern neurootology has proved that many vertigo patients suffer from central dysequilibrium states. As vertigo patients are very frequent amongst our patient population we have to increase our diagnostic as well as therapeutical efforts. Since 1965, eliciting vestibular evoked cortical potentials has been possible. A method of evoked responses based upon computation of several stimulus responses has been used since then. Besides we are also using the frequency analysis of representative epochs of ongoing vestibular-ocular or retino-ocular reactions has been used since then. For diagnostic purposes we are combining various techniques like systematic history taking, ENG, ECG, CCG and BEAM. Brain electrical activity mapping (BEAM) is a newly developed tool, which we can also use for differentiating central from peripheral vestibular diseases. We are applying this technique for topographic correlates of vertigo related functional changes as well as for spatiotemporal analysis of cerebral evoked potentials due to vestibular stimulation. By means of a specific vestibular evoked potential technique, 6 typical cortical wave patterns can be elicited, which are displayed in the EEG curves as well as in colour maps of the whole scalp. The interactions between the various cortical structures are turning into an image similar to a weather map. BEAM, the fourth plan for projecting vertigo disorders, is now also bound into our concept for planning and monitoring a drug based therapy.