Optimized Diagnostic Approach to Patients Suspected of Superior Semicircular Canal Dehiscence

Abstract

Objectives: Current methods of diagnosing superior semicircular canal dehiscence syndrome (SCDS) include a clinical exam, audiometric testing, temporal bone computer tomography (CT) imaging, and vestibular evoked myogenic potential (VEMP) testing. The main objective of this study was to develop an improved diagnostic approach to SCDS optimized for accuracy, efficiency, and safety that utilizes clinical presentation, audiometric testing, CT imaging, high-frequency cervical VEMP (cVEMP) testing, and patient treatment preference. A secondary aim was to investigate the cost associated with the current versus proposed diagnostic paradigms. Design: All patients who underwent cVEMP testing since introduction of the 2 kHz cVEMP in our clinical protocol in July 2018 were screened. Patients suspected of SCDS based upon symptoms who also had available audiogram, CT scan, and 2 kHz cVEMP were included (58 ears). Patients were categorized as dehiscent, thin, or not dehiscent based on their CT scan. Symptom prevalence and cVEMP outcomes were analyzed and compared for all groups. The accuracy of the 2 kHz cVEMP was calculated using CT imaging as the standard. Using a combination of patient symptomatology, audiometric, CT and 2 kHz cVEMP data, as well as patient preference, a best clinical practice approach was developed. The cost associated with this approach was calculated and compared with cost of the current SCDS diagnostic workup using Medicare reimbursement rates. Results: In the overall patient population suspected of SCDS based on clinical presentation, the sensitivity and specificity of 2 kHz cVEMP were 76% and 100%, respectively, while the positive and negative predictive values were 100% and 84.6%, assuming that the CT scan finding was correct. Autophony was the most common symptom in patients who had both superior semicircular canal dehiscence on CT imaging plus abnormal 2 kHz cVEMP (p < 0.001). Combining patient symptomatology, 2 kHz normalized peak to peak cVEMP amplitude, and patient treatment preference to determine, which patients should undergo CT scanning resulted in a potential cost reduction between 45% and 61%. Conclusion: In patients suspected of SCDS based on their clinical presentation, the combination of symptomatology, 2 kHz cVEMP data, and patient preference can be used to determine which patients should undergo CT scanning, resulting in a diagnostic cost reduction and reduced patient radiation exposure.

A Single Fast Test for Semicircular Canal Dehiscence – oVEMP n10 to 4000Hz – Depends on Stimulus Rise-time

“…Once again, the evidence of this study shows that 4000Hz is an excellent test for identifying SCD. We agree with the conclusion of Noij et al: "VEMP tests using high frequency stimuli are the most accurate single diagnostic test for SCD " [17,18].…”

“…Thus a single test, averaging the response to just 50 stimuli at 4000Hz, is a very valuable initial screening test for patients with a suspected SCD [15,16]. Recent developments have been refined to optimize both sensitivity and specificity of high frequency cVEMP and oVEMP for detecting SCD and it has been argued that "VEMP tests using high frequency stimuli are the most accurate single diagnostic test for SCD " [17,18].…”

A Single Fast Test for Semicircular Canal Dehiscence—oVEMP n10 to 4000 Hz—Depends on Stimulus Rise Time

“…In this study, the evidence demonstrates that, once again, 4000 Hz is an excellent test for identifying SCD. We fully agree with the statement by Noij et al that “VEMP tests using high frequency stimuli are the most accurate single diagnostic test for SCD“ [ 17 , 18 ].…”

“…However, in this study, as in our previous study [ 15 ], every single CT-verified SCD patient showed an oVEMP n10 to the 4000 Hz stimuli with short rise times (15 patients in this study, 26 patients in our previous study, for a total of 41 patients with 100% detection). This is convincing evidence that 4000 Hz with a short rise time is an excellent screening test for SCD [ 18 ]. As we have shown, the result is in close accordance with the evidence from the physiology of the effect of SCD on canal afferent neuron responses.…”

“…Therefore, a single test averaging the response to only 50 stimuli at 4000 Hz is a very valuable initial screening test for patients with suspected SCD [ 15 , 16 ]. Recent developments have been refined to optimize both sensitivity and specificity of high frequency cVEMP and oVEMP for detecting SCD and it has been argued that “VEMP tests using high frequency stimuli are the most accurate single diagnostic test for SCD” [ 17 , 18 ].…”