Validating the Utility of High Frequency Ocular Vestibular Evoked Myogenic Potential Testing in the Diagnosis of Superior Semicircular Canal Dehiscence

Introduction:Ocular vestibular evoked myogenic potential (oVEMP) is a diagnostic test employed in the evaluation of superior semicircular canal dehiscence (SSCD) syndrome. Previous work showed that the presence of the n10 component of oVEMP at 4000Hz was diagnostic of SSCD with perfect sensitivity and specificity of 1.0 in a series of 22 patients. This study sought to validate the diagnostic accuracy of high-frequency oVEMP with comparison to 500Hz oVEMP and cervical vestibular evoked myogenic potential (cVEMP) in a larger series of patients.Methods:Retrospective chart review of 171 patients with clinical symptoms consistent with SSCD who underwent oVEMP and cVEMP testing. Dehiscence of the superior semicircular canal (SCC) on high-resolution computed tomography (CT) imaging of the temporal bone was used to identify cases of likely SSCD. The presence or absence of 4000Hz oVEMP n10 responses, increased amplitude of 500Hz oVEMP responses, and reduced threshold of 500Hz cVEMP responses were identified for each patient.Results:SCC dehiscence was identified by CT imaging in 48 of 171 patients with symptoms consistent with SSCD. High-frequency oVEMP testing at 4000z elicited a n10 response in 40 of 48 (83.3%) of patients and was present in 48 of 171 (28.1%) patients overall. The corresponding sensitivity was 0.83, specificity was 0.93, positive predictive value was 0.83, and negative predictive value was 0.93. oVEMP and cVEMP testing at 500Hz was less accurate with sensitivity of 0.62 and 0.64, respectively, and specificity of 0.73 and 0.73, respectively.Conclusion:The presence of a 4000Hz oVEMP n10 response was predictive of SSC dehiscence on CT imaging among patients with symptoms consistent with SSCD with sensitivity of 0.83, specificity of 0.93, positive predictive value of 0.83, and negative predictive value of 0.93. A negative finding strongly rules out SSCD. High-frequency oVEMP was more accurate than 500Hz oVEMP or cVEMP.