Motion sickness susceptibility associated with visually induced postural instability and cardiac autonomic responses in healthy subjects.

CONCLUSIONS

This study supports the hypothesis that postural sway and autonomic responses to moving visual stimuli may be associated with motion sickness susceptibility. Characteristics of the cardiac sympathovagal balance during exposure to provocative stimulation may be a marker of individual susceptibility to motion sickness.

OBJECTIVE

To assess the relationship between postural and autonomic responses to a simulated visual motion environment and reported susceptibility to motion sickness.

MATERIAL AND METHODS

Fifteen healthy subjects were exposed to sinusoidally oscillating visual motion in roll at frequencies of 0.1-0.4 Hz. Recordings were made of postural sway and respiratory frequency and electrocardiograms were obtained from which heart rate variability (HRV) was computed in order to probe cardiac sympathetic and parasympathetic activity.

RESULTS

In subjects with a low susceptibility to motion sickness as rated using a standardized questionnaire, there was no significant effect of visual stimulus on postural sway or HRV at any frequency of motion. Subjects with a high susceptibility to motion sickness showed significant postural instability induced by visual stimuli (p < 0.01). Visual stimuli presented at a frequency of 0.1 Hz significantly increased the low-frequency power (LF) of HRV, decreased the high-frequency power (HF) of HRV and increased the LF:HF ratio in these subjects (p < 0.05).