Efficacy of Vestibulo-Ocular Reflex Gain and Refixation Saccades of Video Head Impulse Test in Identifying Vestibular Pathologies

Abstract

Aim: Video head impulse test is a clinical tool found useful for assessment of each of the 6 semicircular canals independent of each other. However there is little known about relative efficacy of the two measures, vestibulo-ocular reflex gain and refixation saccade, in identifying the presence of a vestibular pathology. The present study therefore aimed at investigating the utility of each of these measures in identifying vestibular pathology. Materials and Methods: Twenty subjects with normal audio-vestibular system and 20 subjects with vestibulopathies underwent video head impulse testing. Results: The VOR gain was significantly higher in lateral and posterior canals and presence of refixation saccades was in significantly higher proportion of individuals with vestibulopathies than the controls (p < 0.05). When presence of either refixation saccades or reduced VOR gain was considered an abnormal result, the sensitivity was ~71% and ~43% and specificity was ~92% and ~82% for lateral and posterior canals respectively. When presence of either refixation saccades or reduced VOR gain for either of the two canals was considered an abnormal result, the sensitivity shot up to reach ~86% whereas the specificity plummeted slightly to drop to75%. Conclusion: The video head impulse test can differentiate vestibulopathies from normal individuals and hence a clinically useful tool.