Effects of the stimulus phase on the air-conducted ocular vestibular evoked myogenic potential in healthy subjects

Abstract

Objective: The study aimed to examine the effect of the stimulus phase of air-conducted sound on ocular vestibular evoked myogenic potentials (oVEMPs).

Methods: oVEMPs were recorded after air-conducted sounds (500Hz, 4ms duration), presented with initial condensation (positive), rarefaction (negative), and alternant polarities from 12 healthy subjects.

Results: Most responses showed a bifid n10 peak separated by ∼1.9ms. The most prominent sub-peak after condensation was shorter than the most prominent sub-peak after rarefaction; however, the first sub-peak was shorter after the rarefaction stimuli. When a third sub-peak appeared, it occurred before the most prominent sub-peak after condensation and after the most prominent sub-peak after rarefaction. The latency difference between this third sub-peak and the closest sub-peak was shorter than the difference among the others sub-peaks, in both cases; the oVEMPs after alternating stimuli was an amalgam of the responses to the different stimuli.

Conclusions: The findings suggest that the negative to positive change of the stimulus was the main event responsible for the stimulation, and that when a third sub-peak appeared it was related to the initiation or the end of the stimulus.

Significance: These findings suggested that the oVEMP response, obtained by air conducted sound, was secondary to stimulation of the same type of afferent vestibular unit, independent of the stimulus polarity.

Keywords: Air conducted sound; Condensation; Latencies; Rarefaction; Vestibular stimulation; oVEMP.