Dissociated Results between Caloric and Video Head Impulse Tests in Dizziness: Prevalence, Pattern, Lesion Location, and Etiology

Background@#and PurposeThis study was designed to determine the prevalence, pattern, lesion location, and etiology of dissociation in the results of the bithermal caloric test and the horizontal video head impulse test (vHIT) in dizzy patients with various etiologies and disease durations. @*Methods@#We analyzed the results of bithermal caloric tests and vHITs performed over 26 months in 893 consecutive patients who underwent both tests within a 10-day period. @*Results@#Dissociation in the results of the two tests was found in 162 (18.1%) patients. Among them, 123 (75.9%) had abnormal caloric tests (unilateral paresis in 118 and bilateral paresis in 5) but normal vHITs. Peripheral lesions were identified in 105 (85.4%) of these patients, with the main underlying diseases being Meniere's disease (62/105, 59%) and vestibular neuritis/labyrinthitis (29/105, 27.6%). In contrast, central pathologies of diverse etiologies were found only in 18 (14.6%) patients. Abnormal vHIT (bilaterally positive in 18, unilaterally positive in 19, and hyperactive in 2) and normal caloric responses were found in 39 patients, with an equal prevalence of central (n=19) and peripheral (n=20) lesions. The peripheral lesions included vestibular neuritis/labyrinthitis in seven patients and Meniere's disease in another seven. The central lesions had diverse etiologies. @*Conclusions@#Dissociation in the results between caloric tests and horizontal vHITs is not uncommon. The present patients with abnormal caloric tests and normal vHITs mostly had peripheral lesions, while central lesions were likely to underlie those with abnormal vHITs and normal caloric tests.

Successful Treatment of Vasovagal Syncope Due to Blood-Injury Phobia by Physical Maneuvering

Blood-injury phobia may present as a vasovagal syncope in response to the sight of blood or after receiving venipuncture. A 26-year-old man presented with a history of syncope induced by venipuncture. A transcranial Doppler (TCD) scan with monitoring of both heart rate and blood pressure reproduced the syncope and showed it to be vasovagal in nature. Treatment by practicing physical maneuvers, such as leg crossing and muscle tensing, improved the condition of the patient. This case suggests that physical maneuvering is effective in the treatment of blood-injury phobia.