Clinical Characteristics of Dizzy Patients Showing Discordant Results Between Bithermal Caloric Test and Video Head Impulse Test.

Background/Objectives: To evaluate the clinical characteristics and diagnostic significance of dissociation between bithermal caloric test and video head impulse test (vHIT) in patients presenting with dizziness. Methods: We retrospectively reviewed 644 patients who underwent bithermal caloric testing and vHIT at a university-affiliated general hospital. Patients were classified into concordant and discordant groups based on test results. The discordant group was further subdivided into those with abnormal caloric test and normal vHIT, and those with normal caloric test and abnormal vHIT. Demographic data, vestibular function test outcomes, and clinical diagnoses were analyzed. Results: Discordant results were observed in 36.5% of patients. Among these, 31.8% had abnormal caloric responses with normal vHIT, and 4.7% had normal caloric responses with abnormal vHIT. Most patients in both discordant subgroups were diagnosed with peripheral vestibular disorders, such as Ménière's disease and unilateral vestibulopathy. The abnormal caloric/normal vHIT pattern was more common and associated with low-frequency dysfunction. The normal caloric/abnormal vHIT pattern, though less frequent, also involved predominantly peripheral etiologies. Conclusions: Dissociation between caloric and vHIT results is not uncommon and provides important diagnostic insights. Employing both tests in a complementary manner enhances the identification of frequency-specific vestibular deficits and supports more accurate diagnosis and management of vestibular disorders.