Caloric and Rotational Testing: Merits, Pitfalls and Myths

Abstract

Objectives: The evaluation of the caloric and the rotational tests in the light of contemporary data on the function and dysfunction of the vestibular system. This is attempted by using novel engineering system notions. Material and Patients: Our work in mathematical modeling of the vestibuloocular reflex. In addition, our data from thousands of patients submitted to caloric testing and more than one hundred patients submitted to rotational testing. Methods: Analysis of results in light of system engineering notions. Results and Conclusions: The caloric test, corresponding to low head velocity and movement frequency, is an excellent test in defining the degree of excitability of one side versus the other. If there is a bilateral loss of vestibular function both, right and left, caloric responses will be compromised. However, the definition of the dynamic condition of the system and the detection of nonlinearities, especially in the presence of pathology, require rotational tests, which will yield such information if data are appropriately processed. Present day knowledge is insufficient on: (1) the functional contribution of the fast phase of nystagmus, (2) the synergistic effects of semicircular canals and otoliths, and (3) the synergistic effects of vestibular and other sensory modalities.