Vertigo and Nystagmus Responses to Caloric Stimuli Repeated at Short Intervals

Abstract

Repeated monoaural caloric stimulations with water of constant temperature at intervals of 10 minutes brought about a progressive decline of the vertigo and nystagmus responses as measured by the mean values of the latency, duration and maximum intensity of the vertigo, the duration of the nystagmus and the total number of nystagmic beats. The calorization series were paired so that they differed in regard to (1) only the labyrinth (left or right), (2) only the temperature of the water (warm or cold), or (3) both the labyrinth and the temperature of the water. The maximum intensity of the vertigo in the second of a paired series appeared to be independent of that in the first series, regardless of the type of pairing. The decline in the vertigo response thus appeared to show a directional specificity linked to the direction of the cupular deflexion in the individual lateral semicircular canal.