船酔い感受性に関する神経耳科学的検討

Abstract

To clarify the relationship between susceptibility to seasickness and the function of the vestibular system, we examined 35 healthy male students in the second year of Toyama Fisheries High School (16 or 17 years old) before and after their first voyage, using the bithermal caloric test and the pendular rotational test (0.05 and 0.1 Hz). The results of the two tests were correlated with the severity of sea sickness, duration of sea sickness and the number of vomiting episodes.Thirty-three of 35 subjects (94%) suffered from sea sickness. The mean duration of sea sickness was 5.3 days, and the mean number of vomiting episodes was 5.5. In both the number of beats and the maximum slow phase velocity of caloric nystagmus, a significant correlation was found between the pre-voyage test results and the difference between the pre-vs. post-voyage test results (p< 0.05). Furthermore, these two parameters in the pre-voyage test were significantly correlated with the duration of sea sickness (p <0.05). As for the rotation test, the pre-voyage VOR gain at the frequency of 0.05 Hz was significantly correlated to the difference in value in the pre-vs. post-voyage VOR gain (p< 0.05). No correlation was found between severity of sea sickness and either pre-or post-VOR gain (0.05 and 0.1 Hz). These findings suggest that the caloric test may be useful in predicting susceptibility to sea sickness.