Vertigo and Nystagmus Responses to Caloric Stimuli Repeated at Short and Long Intervals

Abstract

Experiments on 50 young, and, from an otoneurological point of view, “normal” subjects, showed a decline of the average vertigo and nystagmus responses to repeated monoaural caloric stimulations with water at 30°C. This response decline (R.D.) occurred both at short (8 min) and long (24 hours or more) interstimuli intervals, which indicates that a central mechanism was responsible for this phenomenon. Statistical analysis disclosed some traits in the response pattern characteristic of habituation. Of practical interest is the observation that, even when an interval of two weeks elapsed between the first and second irrigations the nystagmus response to the second irrigation was significantly weaker. This R.D. was more marked in latency, total number of beats and dysrhythmia than in the duration of the nystagmus response.