Clinical Application of Vestibular Tests

Abstract

There are several reasons why vestibular tests have less clinical interest than auditory tests. First, the auditory tests are more pertinent and definitely more localized in the field in which the otologist works. Second, a vestibular test, when completely executed, takes considerable time. Third, the individual variation among patients makes standardization difficult. The highly nervous person, for instance, has a quicker reflex response than the slower, more lethargic person. Finally, at times contradictory findings are disheartening. Still these tests provide a source of much information which will be of value when otologists learn to interpret the findings.Aside from the localization of various lesions in the end organ, the information obtained with these tests could be of great value to neurologists and neurosurgeons ; it seems unlikely, however, that the data obtained by an otologist will ever contribute as much aid as that provided by the ophthalmologist, since the optic nerve runs a more unique intracranial course. The intimate relation with other vital structures, the greater susceptibility to the intracranial pressure and the desiccation of the chiasma all offer opportunities for study which the eighth nerve does not.There have appeared in the literature many clinical reports which would lead one to believe that nearly any kind of intracranial condition can be diagnosed by a vestibular test alone. This is a little misleading, for it is difficult with our present capabilities to make a diagnosis of such a condition without using neurologic signs and symptoms. By the time a diagnosis can be made with neurologic methods, it is too late to be of much value, except to verify a previous diagnosis.However, there are a few instances in which vestibular tests serve a useful purpose, particularly early in the course of a disease, before neurologic signs are well developed. In cases in which nystagmus, vertigo, instability, headache and deafness, either singly or combined, are present, differentiation by means of these tests between a peripheral and a central lesion is of great value. The table offers an outline of differential characteristics which is reliable in all except a few cases.