Impact of artifacts on VOR gain measures by video-oculography in the acute vestibular syndrome

Article type: Research Article

Authors: Mantokoudis, Georgios^{a; b} | Saber Tehrani, Ali S.^b | Wozniak, Amy^c | Eibenberger, Karin^d | Kattah, Jorge C.^e | Guede, Cynthia I.^e | Zee, David S.^b | Newman-Toker, David E.^{b; *}

Affiliations: [a] University Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital Bern, Switzerland | [b] Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA | [c] Johns Hopkins Biostatistics Center, Baltimore, MD, USA | [d] Department of Otolaryngology – Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA | [e] Department of Neurology, Illinois Neurologic Institute, University of Illinois, College of Medicine, Peoria, IL, USA

Correspondence: [*] Corresponding author: David E. Newman-Toker, MD PhD, Associate Professor, Department of Neurology, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, CRB-II, Room 2M-03 North, 1550 Orleans Street, Baltimore, MD 21231, USA. Tel.: +1 443 287 9593; Fax: +1 410 502 7869; E-mail: [email protected].

Abstract: OBJECTIVE: The video head impulse test (HIT) measures vestibular function (vestibulo-ocular reflex [VOR] gain – ratio of eye to head movement), and, in principle, could be used to make a distinction between central and peripheral causes of vertigo. However, VOG recordings contain artifacts, so using unfiltered device data might bias the final diagnosis, limiting application in frontline healthcare settings such as the emergency department (ED). We sought to assess whether unfiltered data (containing artifacts) from a video-oculography (VOG) device have an impact on VOR gain measures in acute vestibular syndrome (AVS). METHODS: This cross-sectional study compared VOG HIT results ‘unfiltered’ (standard device output) versus ‘filtered’ (artifacts manually removed) and relative to a gold standard final diagnosis (neuroimaging plus clinical follow-up) in 23 ED patients with acute dizziness, nystagmus, gait disturbance and head motion intolerance. RESULTS: Mean VOR gain assessment alone (unfiltered device data) discriminated posterior inferior cerebellar artery (PICA) strokes from vestibular neuritis with 91% accuracy in AVS. Optimal stroke discrimination cut points were bilateral VOR gain >0.7099 (unfiltered data) versus >0.7041 (filtered data). For PICA stroke sensitivity and specificity, there was no clinically-relevant difference between unfiltered and filtered data–sensitivity for PICA stroke was 100% for both data sets and specificity was almost identical (87.5% unfiltered versus 91.7% filtered). More impulses increased gain precision. CONCLUSIONS: The bedside HIT remains the single best method for discriminating between vestibular neuritis and PICA stroke in patients presenting AVS. Quantitative VOG HIT testing in the ED is associated with frequent artifacts that reduce precision but not accuracy. At least 10–20 properly-performed HIT trials per tested ear are recommended for a precise VOR gain estimate.

Keywords: Eye movement measurements, vestibulo-ocular reflex, vertigo, vestibular neuritis, stroke, diagnosis

DOI: 10.3233/VES-160587

Journal: Journal of Vestibular Research, vol. 26, no. 4, pp. 375-385, 2016