title: Vestibular testing abnormalities in individuals with motion sickness.
abstract: OBJECTIVE
  The goal of this study was to compare the results of vestibular testing in individuals with motion sickness to a group of control subjects.
  
  
  BACKGROUND
  Studying motion sickness is difficult, because no animal model has been developed and symptoms rarely occur outside motion environments. Tests that can be performed in normal laboratory settings, which help to identify individuals with motion sickness, may be valuable in characterizing this disorder.
  
  
  METHODS
  Twenty active duty military individuals with well-documented motion sickness were tested. The test battery included sinusoidal rotational chair testing to calculate vestibulo-ocular reflex function, step-velocity testing to calculate vestibular time constants, and posturography testing to assess vestibulo-spinal reflex status. The results of this test battery were compared with a set of age- and sex-matched controls without motion sickness.
  
  
  RESULTS
  Vestibular test abnormalities were demonstrated in individuals with motion sickness. Vestibulo-spinal reflex function on posturography was normal in the control group but abnormal in 70% of the individuals with motion sickness. In addition, 5% of the control group demonstrated a minimal shortening of the absolute time constant, whereas 60% of the individuals with motion sickness had abnormal absolute time constants.
  
  
  CONCLUSIONS
  A significant percentage of individuals with motion sickness demonstrate abnormalities in their time constant or vestibulo-spinal reflex function. These abnormalities can be detected using standard, land-based vestibular tests. These preliminary results have implications in understanding the etiology of motion sickness and may provide outcome measures to be used in treating motion sickness.
authors.affiliation: Department of Defense, Spatial Orientation Center, Department of Otolaryngology, Naval Medical Center San Diego, San Diego, CA 92134-2200, USA. mehoffer@nmcsd.med.navy.mil
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hoffer
authors.forename: Kim
authors.initials: K
authors.lastname: Gottshall
authors.forename: Richard D
authors.initials: RD
authors.lastname: Kopke
authors.forename: Peter
authors.initials: P
authors.lastname: Weisskopf
authors.forename: Robert
authors.initials: R
authors.lastname: Moore
authors.forename: Keith A
authors.initials: KA
authors.lastname: Allen
authors.forename: Derin
authors.initials: D
authors.lastname: Wester
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D009041:Motion Sickness / Q000175:diagnosis*; D011187:Posture; D012018:Reflex; D012027:Reflex, Vestibulo-Ocular; D013116:Spinal Cord / Q000503:physiopathology; D013997:Time Factors; D014724:Vestibular Function Tests; D014722:Vestibule, Labyrinth / Q000503:physiopathology