Influence of the Electrode Montage to Detect Ocular Vestibular Evoked Myogenic Potentials

Abstract

Objective To compare ocular vestibular evoked myogenic potentials (oVEMPs) obtained with three different electrode montages (infra-orbital vs belly-tendon vs chin) in a group of healthy subjects. To assess the electrical activity recorded at the level of the reference electrode in the belly-tendon and chin montages. Study Design Prospective study. Setting Tertiary referral center. Patients Twenty-five healthy adult volunteers. Intervention(s) Each ear was tested separately via air-conducted sound (500 Hz Narrow Band CE-Chirps at 100 dB nHL) for recording contralateral myogenic responses. Recording conditions were randomized. Main Outcome Measure(s) n1-p1 amplitudes values, interaural amplitude asymmetry ratios (ARs) and response rates. Results The belly-tendon electrode montage (BTEM) produced larger amplitudes than the chin (p = 0.008) and the IOEM (infra-orbital electrode montage; p < 0.001). The chin montage displayed larger amplitudes than the IOEM (p < 0.001). The interaural amplitude asymmetry ratios (ARs) were not affected by the different electrode montages (p = 0.549). In 100% of cases, oVEMPs were detected bilaterally with the BTEM which is higher than with the chin and the IOEM (p < 0.001; p = 0.020, respectively). We did not record any VEMP when placing the active electrode on the contralateral internal canthus or the chin and the reference electrode on the dorsum of the hand. Conclusions The BTEM increased the amplitudes recorded and response rate in healthy subjects. No positive or negative reference contamination was observed with the belly-tendon or chin montages.