title: VOR gain by head impulse video-oculography differentiates acute vestibular neuritis from stroke.
abstract: OBJECTIVE
  Vestibular neuritis is often mimicked by stroke (pseudoneuritis). Vestibular eye movements help discriminate the two conditions. We report vestibulo-ocular reflex (VOR) gain measures in neuritis and stroke presenting acute vestibular syndrome (AVS).
  
  
  METHODS
  Prospective cross-sectional study of AVS (acute continuous vertigo/dizziness lasting >24 h) at two academic centers. We measured horizontal head impulse test (HIT) VOR gains in 26 AVS patients using a video HIT device (ICS Impulse). All patients were assessed within 1 week of symptom onset. Diagnoses were confirmed by clinical examinations, brain magnetic resonance imaging with diffusion-weighted images, and follow-up. Brainstem and cerebellar strokes were classified by vascular territory-posterior inferior cerebellar artery (PICA) or anterior inferior cerebellar artery (AICA).
  
  
  RESULTS
  Diagnoses were vestibular neuritis (n = 16) and posterior fossa stroke (PICA, n = 7; AICA, n = 3). Mean HIT VOR gains (ipsilesional [standard error of the mean], contralesional [standard error of the mean]) were as follows: vestibular neuritis (0.52 [0.04], 0.87 [0.04]); PICA stroke (0.94 [0.04], 0.93 [0.04]); AICA stroke (0.84 [0.10], 0.74 [0.10]). VOR gains were asymmetric in neuritis (unilateral vestibulopathy) and symmetric in PICA stroke (bilaterally normal VOR), whereas gains in AICA stroke were heterogeneous (asymmetric, bilaterally low, or normal). In vestibular neuritis, borderline gains ranged from 0.62 to 0.73. Twenty patients (12 neuritis, six PICA strokes, two AICA strokes) had at least five interpretable HIT trials (for both ears), allowing an appropriate classification based on mean VOR gains per ear. Classifying AVS patients with bilateral VOR mean gains of 0.70 or more as suspected strokes yielded a total diagnostic accuracy of 90%, with stroke sensitivity of 88% and specificity of 92%.
  
  
  CONCLUSIONS
  Video HIT VOR gains differ between peripheral and central causes of AVS. PICA strokes were readily separated from neuritis using gain measures, but AICA strokes were at risk of being misclassified based on VOR gain alone.
authors.affiliation: *Department of Neurology, Johns Hopkins University School of Medicine; †Johns Hopkins Biostatistics Center; and ‡Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, U.S.A.; §University of Applied Sciences Upper Austria, Department of Medical Engineering, Linz, Austria; and ║University of Illinois College of Medicine, Peoria, Illinois, U.S.A.
authors.forename: Georgios
authors.initials: G
authors.lastname: Mantokoudis
authors.forename: Ali S Saber
authors.initials: AS
authors.lastname: Tehrani
authors.forename: Amy
authors.initials: A
authors.lastname: Wozniak
authors.forename: Karin
authors.initials: K
authors.lastname: Eibenberger
authors.forename: Jorge C
authors.initials: JC
authors.lastname: Kattah
authors.forename: Cynthia I
authors.initials: CI
authors.lastname: Guede
authors.forename: David S
authors.initials: DS
authors.lastname: Zee
authors.forename: David E
authors.initials: DE
authors.lastname: Newman-Toker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology; D014717:Vertigo / Q000175:diagnosis* / Q000503:physiopathology; D020338:Vestibular Neuronitis / Q000175:diagnosis* / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*