084 Separating stroke from vestibular neuritis by vestibular function test parameters

Abstract

IntroductionVestibular neuritis (VN) and posterior circulation stroke (PCS) are the commonest causes of acute vestibular syndrome (AVS). We aim to identify discriminators of VN from PCS by testing all five vestibular end-organs in patients presenting with AVS.MethodsThree-dimensional video-head impulse test (v-HIT), cervical and ocular-vestibular evoked myogenic potentials (c-and oVEMP) and subjective visual horizontal (SVH) tests were performed in 22 patients with VN and 22 with PCS. Ipsilesional horizontal, anterior and posterior canal (HC, AC, PC) v-HIT gain and first catch-up saccade characteristics, VEMP amplitude asymmetry-ratios were compared.ResultsAll VN and 6 PCS patients had positive clinical HIT. Mean time to testing was 4.7 days for VN, 7.0 days for PCS. VN mean ipsilesional HC and AC first saccade amplitude was larger, peak-velocities faster and onset latencies earlier compared to PCS (p<0.05). No significant difference between VN and PCS in first saccade characteristics was found in PC. Ipsilesional first saccade amplitude, peak-velocity and duration were significantly different between PCS and controls for all canals (p<0.05). A gain <0.68 and first saccade amplitudes >2.2°separated VN from PCS with sensitivities of 95.5% and 86.4% and specificities of 72.7% and 63.6%. First saccade amplitude of >0.91°identified PCS from controls with sensitivity of 68.2% and specificity of 70%. Abnormality rates for AC cVEMP, BC oVEMP and SVH were 42.9%, 50% and 91% for VN and 38.1%, 9% 72% for PCS.Conclusion v-HIT gain and catch-up saccade metrics are useful separators of VN from PCS. Detailed saccade analysis complements existing vestibular tests.