[Significance of comparing the results of caloric and vestibulometric rotation tests]

The use of modified, less laborious, easier endured vestibulometric tests made it possible to facilitate diagnosing Menière's disease and neurinomas of the vestibular nerve. Comparison of nystagmometric findings recorded in the same patient during caloric and rotation tests using the diagnostic model of a bithermal test permitted some assumptions to be made in relation to the mechanisms for nystagmogenesis associated with pathologic states in ear labyrinth and vestibular portion craniocerebral (VIII) nerve. It is found that in the majority of Meniere's disease cases (61%) there is a decrease in an intensity of caloric nystagmus induced by Lasix dehydration effect. This phenomenon can be explained by a reduced difference in energy levels of two complexes of vestibular nuclei and, therefore, by an attenuated afferents to peripheral compartment of vestibular system. In neurinoma of aural nerve, the phenomenon of vestibular recruitment (20%) was noted. The diagnostic model of a bithermal test makes it possible to explain an effect of smoothing out the nystagmic responses induced by an intensive stimulus when used a sinusoidal stepwise test. The observed vestibular recruitment results from the severe disorder of one of the afferent inputs due to destruction of induced by tumor pressure.