Ocular vestibular evoked myogenic potentials in response to air-conducted 500 Hz short tones: effect of stimulation procedure (monaural or binaural), age and gender

BACKGROUND: The ocular vestibular myogenic potentials (oVEMP) can be elicited by monaural air-conducted sound stimulation, and are usually recorded from the contralateral eye. In clinical setting a binaural stimulation would save time and require less effort from the subjects.
OBJECTIVE: We evaluated the differences between monaural and binaural stimulation, and the possible effect of age and gender on oVEMP parameters.
METHODS: Air-conducted oVEMP were recorded by binaural and by monaural stimulation in a group of 54 normal subjects, aged from 12 to 83 years, and in 50 vestibular patients. From each side, we measured the latency of the N1 component, and the peak-to-peak N1-P1 amplitude. For both parameters we also computed the asymmetry ratio.
RESULTS: In normal subjects binaural stimulation produced slightly larger responses than monaural stimulation; detectability, latency and amplitude ratio were the same for the two techniques. We found no differences related to gender, and the age-induced amplitude decline was likely to be negligible.oVEMP recorded not in an acute phase of their disorder, proved to be abnormal in about 20% of the patients, and the normal or abnormal findings obtained either with monaural or with binaural stimulation were always concordant.
CONCLUSIONS: The oVEMP obtained after binaural and monaural stimulation are very similar, and they are largely independent from age and gender.