Diagnostic Accuracy of Ocular Vestibular Evoked Myogenic Potentials for Superior Canal Dehiscence Syndrome in a Large Cohort of Dizzy Patients

Objectives: To determine the diagnostic accuracy of ocular vestibular evoked myogenic potentials (oVEMPs) for superior canal dehiscence syndrome (SCDS) in a large cohort of unselected dizzy patients. Most SCDS patients are dizzy (90%); however, only 30% demonstrate archetypical SCDS clinical proxies (Tullio or Hennebert findings). Several case-control studies have addressed specific SCDS markers using VEMP testing, but the diagnostic value of VEMP for SCDS has not been demonstrated in a target population of dizzy patients. The aim of this study was to confirm the diagnostic properties of oVEMP for SCDS in an unselected cohort of dizzy patients. Design: This diagnostic accuracy study was performed in a tertiary referral center and included a consecutive sample of dizzy patients referred for vestibular function testing. One hundred fifty subjects were collected prospectively; five were excluded due to middle ear disorders, 10 had the target condition (SCDS group), and 135 had an alternative condition (non-SCDS group), based on diagnostic criteria for SCDS used in our department as reference standard. The non-SCDS group was subdivided into diagnostic categories including an "undefined dizziness" group. The index test applied to the total sample (missing data: 1%) consisted of oVEMP recording using three different stimulation modalities, that is, air-conducted (AC) sound stimulation and midsagittal bone-conducted (BC) vibration at both forehead (Fz) and vertex (Cz). Data analysis was conducted on four oVEMP parameters: amplitude, latency, amplitude asymmetry ratio, and interaural latency difference. Between-group analysis was conducted with nonparametric tests. The oVEMP diagnostic accuracy for SCDS was determined with uni/multiparametric receiver operating characteristic analysis. Best cutoff points were computed for those parameters or parameter combinations that showed an accuracy level appropriate for clinical use (area under the curve [AUC] > 0.8). Results: Different oVEMP parameters, in particular, the amplitude to AC stimulation (SCDS: 53, inter quartile range [IQR]: 27.6–68.3 µV; non-SCDS: 4.4, IQR: 2.0–8.1 µV; p

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