title: Mal de debarquement, motion sickness and the effect of an artificial horizon.
abstract: BACKGROUND
  Exposure to unfamiliar motion patterns commonly results in motion sickness and a false perception of motion, termed mal de debarquement, on the return to stable conditions.
  
  
  OBJECTIVE
  To investigate whether motion sickness severity is correlated with the duration and severity of mal de debarquement; to study the possible preventive effect of projecting earth-referenced scenes (an artificial horizon) during exposure to motion on the development of mal de debarquement.
  
  
  METHODS
  Thirty subjects were exposed to the recorded motion profile of a boat in a 3-degrees-of-freedom ship motion simulator. During the simulated voyage, the study participants were repeatedly put through a performance test battery and completed a motion sickness susceptibility questionnaire, while self-referenced and earth-referenced scenes were projected inside the simulator cabin. Six hours post disembarkation, subjects completed a questionnaire on mal de debarquement duration and severity.
  
  
  RESULTS
  Mal de debarquement, mostly of mild severity, was reported following 59% of the exposures to the provocative motion profile, and in 79% of cases lasted less than 6 hours. The incidence of mal de debarquement, its duration, and the severity of symptoms did not differ between the various artificial horizon projection modes. Significant correlations were found between motion sickness severity and the duration and severity of the mal de debarquement that followed.
  
  
  CONCLUSIONS
  The significant correlations found between motion sickness severity and mal de debarquement duration and severity imply that both syndromes might stem from a failure to adapt to new motion conditions. There is a disparity between the previously reported reduction in motion sickness symptoms by an artificial horizon, and its failure to influence the duration and symptoms of mal de debarquement. This might be explained by the different response in the two syndromes, physical versus cognitive.
authors.affiliation: The Motion Sickness and Human Performance Laboratory, The Israel Naval Medical Institute, Haifa, Israel.
authors.forename: Dror
authors.initials: D
authors.lastname: Tal
authors.affiliation: The Motion Sickness and Human Performance Laboratory, The Israel Naval Medical Institute, Haifa, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Wiener
authors.affiliation: The Motion Sickness and Human Performance Laboratory, The Israel Naval Medical Institute, Haifa, Israel Unit of Otoneurology, Lin Medical Center, Haifa, Israel The Bruce Rappaport Faculty of Medicine, The Technion, Haifa, Israel.
authors.forename: Avi
authors.initials: A
authors.lastname: Shupak
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000293:Adolescent; D000328:Adult; D006801:Humans; D008297:Male; D009038:Motion; D009041:Motion Sickness / Q000517:prevention & control*; D014195:Travel; D000076082:Travel-Related Illness
keywords: Mal de debarquement; motion perception; motion sickness; prevention; questionnaires; vestibular organs