Comparison of Caloric and Video Head Impulse Test (vHIT) Results in Common Vestibular Disorders

Abstract

The video head impulse (vHIT) and caloric test are diagnostic tools to examine the horizontal vestibulo-ocular reflex (hVOR), however, are thought to probe different frequencies of the semicircular canals (caloric, low-frequency; vHIT, high-frequency). Despite the tests being used clinically, the sensitivity of the tests to different disorders is unclear due to limitations of previous studies. This study was undertaken to investigate the relationship between the two tests, depending on the disease, and the change in vHIT sensitivity and agreement with the caloric test upon inclusion of additional outcome measures. hVOR was measured in 71 normal participants to establish norms for vHIT gain, gain asymmetry (GA) and saccades rate (SR). vHIT and caloric results of 118 patients diagnosed with Ménière's disease (MD) (n=41), vestibular neuritis/labyrinthitis (VN/VL) (n=38), vestibular migraine (VM) (n=31), and vestibular schwannoma (VS) (n=8) were retrospectively analysed to determine abnormality rates for each test. Outcome measures of gain, GA, SR and caloric canal paresis (CP) were analysed and compared between the disease groups. Abnormality rates were highest in VN/VL and lowest in VM. Overall rates of abnormal vHIT increased from 31.4% to 41.5% with the inclusion of GA and SR, and correlations between caloric and vHIT improved. VN/VL and VM showed no significant differences between vHIT outcome measures and caloric CP. In MD, significantly higher abnormality rates were found for caloric CP compared with all three vHIT outcome measures, and between caloric CP and vHIT gain in VS. The pattern of an abnormal caloric and normal vHIT was observed more frequently in MD with a caloric CP of 38% (in the presence of normal vHIT) discriminating MD from alternate diagnoses with 90% specificity and 49% sensitivity. VN/VL and VM showed agreement between the caloric test and vHIT, while VS showed agreement upon inclusion of GA and SR. MD consistently showed disagreement between the two tests and this dissociation may be used as a diagnostic marker for MD. The profile of test results identified in this study may complement information from the clinical examination and history in the diagnostic work-up for patients with vestibular dysfunction and aid in differential diagnoses.