Desensitization to strong vestibular stimuli improves tolerance to simulated aircraft motion.
BACKGROUND
The extent to which tolerance acquired in one motion environment can be transferred to another has not been fully elucidated. This study compares three provocative motion stimuli and whether tolerance acquired from cross-coupled motion and torso rotation can be transferred to simulated aircraft motion.


METHODS
There were 18 healthy subjects (9 men and 9 women), 18-44 yr of age, who were divided into 3 groups. Each group was exposed to the following desensitization procedure in a pseudo-random repeated measures design. In condition D1, subjects were exposed to 4 consecutive days of cross-coupling and on the 5th d they were exposed to simulated aircraft motion. In D2, subjects were exposed to 4 consecutive days of torso rotation and on the 5th day they were exposed to the simulated aircraft motion as in D1. In D3, subjects were exposed to 5 consecutive days of simulated aircraft motion. Based on Graybiel's diagnostic criteria, severity of motion sickness on the 1st and 5th day in D1, D2, and D3 were compared.


RESULTS
Cross-coupled motion was the most provocative stimulus followed by torso rotation and simulated aircraft motion. Within each motion stimulus, there was evidence of desensitization (p < 0.001) within 4 d. There were no significant differences in the severity of motion sickness observed on the 5th day regardless of the desensitization stimuli.


CONCLUSIONS
Our results suggest that desensitization to one provocative motion could be transferred to a less severe motion stimulus. This result could be used in the refinement of desensitization programs for aircrew.
Cheung
Bob
B
Operational Medicine, DRDC Toronto, Department of National Defence, 1133 Sheppard Ave. W., P.O. Box 2000, Toronto, Ontario, Canada. Bob.Cheung@drdc-rddc.gc.ca
Hofer
Kevin
K
D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000401:Aircraft; D000704:Analysis of Variance; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D008297:Male; D009041:Motion Sickness / Q000503:physiopathology* / Q000517:prevention & control*; D012399:Rotation; D014722:Vestibule, Labyrinth / Q000502:physiology*