Evaluation of guinea pig model for ocular and cervical vestibular-evoked myogenic potentials for vestibular function test.

OBJECTIVES/HYPOTHESIS This study used air-conducted sound (ACS) and bone-conducted vibration (BCV) stimuli in eliciting ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) in guinea pigs. STUDY DESIGN Prospective study. METHODS Ten guinea pigs were treated with gentamicin (4 mg) on the left ear, whereas the right ear served as a control. One week after treatment, each animal underwent oVEMP and cVEMP tests using ACS and BCV modes in a randomized order, and was sacrificed for morphological study. RESULTS Using ACS mode, oVEMPs were absent in all 10 (100%) animals despite the stimulus intensity increased up to 120 dB pe SPL. Conversely, using BCV mode, oVEMPs were present on the left (lesion) eye, and absent on the right (control) eye in all (100%) animals. For the cVEMPs via ACS mode, all right (control) necks had clear cVEMPs, and all (100%) left (lesion) necks revealed absent cVEMPs. However, via BCV mode, all right (control) necks and six (60%) left (lesion) necks showed clear cVEMPs. Morphological study demonstrated substantial loss of hair cells in the utricular and saccular macula. CONCLUSIONS The cVEMP test via ACS mode is specific for investigating the saccular disorder, whereas the oVEMP test via BCV mode is preferable for investigating the utricular disorders in humans. The guinea pig model is consistent with the findings of humans. Restated, appropriate animal models for cVEMP and oVEMP in guinea pigs are via ACS and BCV modes, respectively.