Acoustic, mechanical and galvanic stimulation modes elicit ocular vestibular-evoked myogenic potentials

This study compared the characteristic parameters of ocular vestibular-evoked myogenic potentials (oVEMPs) elicited by the air-conducted sound (ACS) and bone-conducted vibration (BCV) stimulation modes as well as the galvanic vestibular stimulation (GVS) mode.

Fifteen healthy subjects underwent oVEMP tests using ACS (127 dBSPL), BCV (142dB force level), and GVS (5mA) modes. The response rate, latencies of nI and pI, nI-pI interval and amplitude were measured for each mode and compared among modes.

All 15 healthy subjects (30 ears) had 100% response rates in both BCV- and GVS-oVEMPs, exhibiting a response rate significantly higher than 80% in ACS-oVEMPs. The mean nI latency was the shortest in the GVS mode, followed by BCV and then ACS modes. The variation among the latencies of the three modes was significant. Likewise, the mean nI-pI amplitudes in ACS-, BCV- and GVS modes varied significantly. However, the mean nI-pI interval did not differ significantly among the three modes.

Among the ACS (127 dBSPL), BCV (142dB force level), and GVS (5mA) modes, the BCV mode yields a 100% response rate and the largest nI-pI amplitude of oVEMPs.

The oVEMPs in ACS and GVS modes may help to differentiate the saccular from the retro-saccular lesions. If ACS-oVEMPs are normal, then oVEMPs in BCV and GVS modes can distinguish between utricular and retro-utricular disorders. Restated, oVEMPs in ACS, BCV, and GVS modes may promote the topographical delineation of the lesion site of the otolithic-ocular reflex pathway.