Abstract
The purpose of this study was to investigate whether nausea or gastric dysrhythmia including tachygastria, which was determined by electrogastrography (EGG), were observed during optokinetic motion sickness in Japanese healthy volunteers. Twelve healthy Japanese volunteers (nine men and three women) participated in the present study. Subjects were asked to sit in a chair with their heads positioned in the center of a drum with the inside painted with black and white stripes. After a 15-min resting period, the drum was rotated at a speed of 60 degree/s for 15 min. EGG was continuously recorded for a total of 45 min (15-min resting period, 15-min rotation period, and 15-min recovery period). The severity of nausea was evaluated with a visual analogue scale (VAS) before, immediately after and 15-min after cessation of drum rotation. Other motion sickness symptoms were evaluated by scores of subjective symptoms of motion sickness (SSMS). Of 12 subjects who completed the study, ten complained of nausea immediately after cessation of drum rotation. The VAS score for nausea immediately after the drum rotation period and 15 min after cessation of the rotation was significantly higher than at the resting period. EGG during the drum rotation period showed a decrease in normogastria, which was accompanied with an increase in tachygastria. We conclude that gastric tachyarrhythmia and nausea may be induced by viewing an optokinetic rotating drum in healthy Japanese subjects who may have a hyper-susceptibility to vection-induced motion sickness. The gastric dysrhythmia obtained with EGG could be a useful observation to support the appearance of nausea induced by optokinetic motion sickness.
