Air-conducted oVEMPs provide the best separation between intact and superior canal dehiscent labyrinths

OBJECTIVE: First, to define the best single-step suprathreshold screening test for superior canal dehiscence syndrome (SCDS); second, to obtain further insight into the relative sensitivity of vestibular afferents to sound vibration in the presence of a superior canal dehiscence. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Eleven patients with surgically confirmed SCDS (mean, 50 yr; range, 32-66 yr) and 11 age-matched, healthy subjects (right ear only) with no hearing or vestibular deficits (mean, 50 yr; range, 33-66 yr). INTERVENTION: All subjects completed ocular and cervical vestibular evoked myogenic potential (o-and cVEMP) testing in response to air conduction (click and 500 Hz tone burst) and midline bone conduction (reflex hammer and Mini-shaker) stimulation. MAIN OUTCOME MEASURES: OVEMP n10 amplitude and cVEMP corrected peak-to-peak amplitude. RESULTS: OVEMP n10 amplitudes were significantly higher in SCDS when compared with healthy controls in response to all stimuli with the exception of reflex hammer. Likewise, cVEMP-corrected peak-to-peak amplitudes were significantly higher in SCDS when compared with healthy controls for air conduction stimulation (click and 500 Hz toneburst). However, there were no significant differences between groups for midline taps (reflex hammer or mini-shaker). Receiver operating characteristic curves demonstrated that oVEMPs in response to air conduction stimulation provided the best separation between SCDS and healthy controls. CONCLUSION: OVEMPs in response to air conduction stimulation (click and 500 Hz toneburst) provide the best separation between SCDS and healthy controls and are therefore the best single-step screening test for SCDS.