Vestibular evoked myogenic potentials.

A pilot study was undertaken in our Vestibular Disorders Clinic to re-evaluate the clinical benefits of vestibular evoked myogenic potentials (VEMP). In seven normal subjects and 20 documented unilateral peripheral vestibular disorder patients, electromyograms were recorded from surface electrodes over the sternomastoid muscles and averaged in response to 0.1-millisecond clicks played through headphones. Control patients demonstrated EMG positive-negative potentials (p14-n21) of equivalent latencies and amplitudes both ipsilateral and contralateral to the stimuli. In patients with documented unilateral peripheral vestibular disorders, the p14-n21 potentials were preserved in the presence of sensorineural hearing loss and absent in those patients with partial or total vestibular loss. A high directional correlation is noted between the p14-n21 potential and gold-standard caloric testing. We suspect the origin of the response may be in the saccule and suggest that VEMP testing may be useful in assessing intact vestibulocollic pathways in humans.