Usefulness of the head-tilt caloric test as a simple method to evaluate the functions of the vertical semicircular canals

Abstract

The caloric reported by us previously can be used as a simple method to check the functions of the vertical semicircular canals. We evaluated the clinical usefulness of this test in this study. We examined the ENG recordings of 154 ears of 80 patients who underwent the head-tilt caloric test and showed normal caloric response of the horizontal component.In 49 of the 154 ears (32%), the results of the head-tilt caloric test could not be evaluated due to the following reasons: blinking and unstable eye movements in 31 ears, pseudo-vertical component in the ENG recordings in 10 ears, and presence of a vertical component in spontaneous or positional nystagmus in 8 ears.In the remaining 105 ears (68%) for which the results of the head-tilt caloric test could be evaluated, 51 showed responses of both the anterior and posterior canals, 29 showed response of only the posterior canal , 14 showed response of only the anterior canal, and 11 showed no response of either vertical canal.In short, the head-tilt caloric test could detect the function of at least one of the vertical canals in 90% (94/105) of the ears for which the results of the test could be properly evaluated and 61% (94/154) of the ears for which the test was performed. Therefore, we believe that the head-tilt caloric test is applicable in daily practice for screening of the vertical canal functions.In addition, we compared the results of the head-tilt caloric test for the right and left ears. Both ears showed basically the same results, although the response rate of the anterior canal of the left ear, in which the test was performed last, was the lowest.