Diagnostic advantages of the Torok monothermal differential caloric test.

In the Torok monothermal differential caloric test, each ear is irrigated with 10 ml and 100 ml of water at 20 degrees C in 5 and 20 sec., respectively. The intensity of the induced nystagmus is expressed in terms of frequency at culmination. The ratio between the weak and strong caloric responses may be normal of disproportionately large or small. When large, the ratio exceeds 3.5 and is called vestibular decruitment, a sign of labyrinthine disease. A ratio of 1.1 or less is called vestibular decruitment, a sign indicative of posterior fossa abnormality. Of 54 patients showing decruitment, a central lesion was confirmed in 51, an identification rate of 94%. The test is thus valuable in differentiating labyrinthine from retrolabyrinthine lesions.