Evaluation of vestibular evoked myogenic potentials

In previous studies, electromyographic potentials, recorded in response to auditory clicks, have been attributed to stimulation of the otolith (saccule) and have been termed vestibular evoked myogenic potentials (VEMPs). In this study, we assessed the VEMPs in subjects with normal auditory brainstem evoked responses, with no history of vestibular symptoms or neck and other skeletal muscle abnormalities. To this effect, 32 subjects (64 ears), after ethics committee approval, were exposed to 75, 150, and 300 clicks at 100 dB, and the responses were averaged. Electromyographic activity was recorded by applying surface electrodes over the sternocleiodomastoid muscle under the following three conditions: no muscle contraction/no clicks, muscle contraction/no clicks, and muscle contraction/clicks. Our findings suggest that electromyographic responses have to be obtained, during muscle contraction, first without and then with clicks. Our data also suggest that comparison of these two recordings is necessary for meaningful results.