New Proposal of Functional Status of Vestibular System Based on Vestibular Function Tests Findings in Dizzy Patients with Normal Caloric Response

Youm, Hye Youn; Cho, Yang Sun; Hong, Sung Hwa; Chung, Won Ho

Abstract

BACKGROUND AND OBJECTIVES
Vestibular function tests are very useful in diagnosing dizzy patients. Among them, bithermal caloric test is most commonly used test for localizing their permanent vestibular loss. However, it causes much discomfort to the patients with non-physiologic stimuli. In addition, it doesn't represent the present functional status of vestibular system. Therefore, normal caloric result does not accurately correspond to normal vestibular function in dizzy patients. Currently, rotation chair test and dynamic posturography have been introduced adjunctly to assess vestibular function accompanied by bithermal caloric test. It has not been elucidated for their specific role in diverse settings of vestibular disorders. So we planned this study to evaluate clinical usefulness of rotation chair test, videonystagmography and computerized dynamic posturogr-phy in dizzy patients with normal caloric response.
MATERIALS AND METHODS
We reviewed clinical records of 46 patients who met their inclusion criteria. They were categorized into five subgroups according to abnormal vestibular function test findings.
RESULTS
In each subgroup, we hypothesized its clinical relevance, possible mechanism of dizz-iness and presumed diagnosis. Five categories are as below; visual dependency, imbalance of vestibular tones, chronic peripheral vestibulopathy, abnormality in the vestibulospinal tract and abnormality of oculomotor system.
CONCLUSION
We suggest new classification of abnormal vestibular functional status in dizzy patients with normal caloric results. These are comparable according their clinical features and thought to be helpful in managing and counseling each patient.