VESTIBULAR EVOKED MYOGENIC POTENTIALS

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