Examination on factors affecting vertigo induced by the caloric nystagmus test

We studied how individual subject factors that are assumed to be involved in the dizziness symptom induced by the caloric test, such as autonomic imbalance, depressive state, anxious tendency and orthostatic dysregulation (OD) are correlated with dizziness in healthy subjects with normal inner ear function. Subjects who perceived a whirling sensation in the ears after the caloric test showed a significantly increased autonomic symptom score, based on the Graybiel's motion sickness score, as compared to those who perceived a sensation of fluid flowing sideways in the ears. In addition, the duration of nystagmus was significantly longer in the subjects with whirling sensation than in other subjects. The results of psychological testing and interviews revealed a significantly higher depression score as well as higher prevalence of OD in the group with a persistent whirling sensation in both ears as than in the group with a sensation of fluid flowing sideways in both ears, however, there was no significant correlation between the tendency towards autonomic imbalance and anxiety and these sensations in these settings.