title: Detection of isolated covert saccades with the video head impulse test in peripheral vestibular disorders.
abstract: OBJECTIVE
  The function of the semicircular canal receptors and the pathway of the vestibulo-ocular-reflex (VOR) can be diagnosed with the clinical head impulse test (cHIT). Recently, the video head impulse test (vHIT) has been introduced but so far there is little clinical experience with the vHIT in patients with peripheral vestibular disorders. The aim of the study was to investigate the horizontal VOR (hVOR) by means of vHIT in peripheral vestibular disorders.
  
  
  METHODS
  Using the vHIT, we examined the hVOR in a group of 117 patients and a control group of 20 healthy subjects. The group of patients included vestibular neuritis (VN) (n=52), vestibular schwannoma (VS) (n=31), Ménière's disease (MD) (n=22) and bilateral vestibulopathy (BV) (n=12).
  
  
  RESULTS
  Normal hVOR gain was at 0.96 ± 0.08, while abnormal hVOR gain was at 0.44 ± 0.20 (79.1% of all cases). An abnormal vHIT was found in VN (94.2%), VS (61.3%), MD (54.5%) and BV (91.7%). Three conditions of refixation saccades occurred frequently in cases with abnormal hVOR: isolated covert saccades (13.7%), isolated overt saccades (34.3%) and the combination of overt and covert saccades (52.0%).
  
  
  CONCLUSIONS
  The vHIT detects abnormal hVOR changes in the combination of gain assessment and refixation saccades. Since isolated covert saccades in hVOR changes can only be seen with vHIT, peripheral vestibular disorders are likely to be diagnosed incorrectly with the cHIT to a certain amount.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery and Communication Disorders, Helios-Clinic Berlin-Buch, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Blödow
authors.forename: Sebastian
authors.initials: S
authors.lastname: Pannasch
authors.forename: Leif Erik
authors.initials: LE
authors.lastname: Walther
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D064087:Head Impulse Test / Q000379:methods*; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000175:diagnosis* / Q000503:physiopathology; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000175:diagnosis* / Q000503:physiopathology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012438:Saccades; D012665:Semicircular Canals / Q000503:physiopathology; D014717:Vertigo / Q000175:diagnosis* / Q000503:physiopathology; D015837:Vestibular Diseases / Q000175:diagnosis / Q000503:physiopathology; D020338:Vestibular Neuronitis / Q000175:diagnosis* / Q000503:physiopathology; D014741:Video Recording; D055815:Young Adult