title: Motorized head impulse rotator for horizontal vestibulo-ocular reflex: Normal responses.
abstract: OBJECTIVE
  To characterize the horizontal angular vestibulo-ocular reflex using a new motorized head impulse rotator and electro-oculography technique.
  
  
  METHODS
  Prospective case-control study.
  
  
  METHODS
  We included 22 healthy volunteers with unpredictable, horizontal motorized head impulses with a mean velocity of 170 degrees/s and a mean acceleration of 1550 degrees/s2. We recorded head and eye position and calculated gain, asymmetry, and latency of the vestibulo-ocular reflex. All subjects underwent testing twice while viewing a far (140 cm) target to evaluate the repeatability of the measurement. In addition, 8 of these subjects underwent testing while viewing a near (15 cm) target. We reported findings as mean +/- SD.
  
  
  RESULTS
  The mean gain during the 30-millisecond interval before peak head velocity and during the interval when head velocity ranged from 100 degrees /s to 120 degrees/s was 1.08 +/- 0.10. The mean asymmetry in gain between sides was 3.7% +/- 2.8%, and the mean latency of the vestibulo-ocular reflex was 3.4 +/- 6.3 milliseconds. There was a statistically significant correlation between consecutive gain measurements for each subject (r = 0.59; P=.004). The mean gain for the near target was 1.26 +/- 0.10 and was significantly higher than that for the far target (P = .002).
  
  
  CONCLUSIONS
  The vestibulo-ocular reflex measurements using our novel system are comparable to those achieved using other techniques. These results suggest that a motorized head impulse rotator with electro-oculography allows reliable and fast measurement of the vestibulo-ocular reflex. In addition, the method is safe, repeatable, and thus could be a useful tool in the clinical assessment of the vestibulo-ocular reflex.
authors.affiliation: Department of Otolaryngology, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Meeli
authors.initials: M
authors.lastname: Hirvonen
authors.forename: Heikki
authors.initials: H
authors.lastname: Aalto
authors.forename: Americo Aniello
authors.initials: AA
authors.lastname: Migliaccio
authors.forename: Timo Petteri
authors.initials: TP
authors.lastname: Hirvonen
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D012016:Reference Values; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation