The ice-water caloric test.

CONCLUSIONS

Three possible results are commonly seen after ice-water caloric irrigation and to correctly interpret them the function of the corresponding vestibular receptor and of normal endolymphatic flow must be taken into account. Bedside vestibular examination helps to interpret discrepant findings.

OBJECTIVE

To review the findings obtained with the ice-water caloric test in patients with dizziness and to compare the results with those of the bedside test.

PATIENTS AND METHODS

The study was undertaken in a university hospital, tertiary medical center. The indications to perform the ice-water caloric test were: 1) unilateral canal weakness >90%; 2) a maximum slow phase velocity of nystagmus after hot (44 degrees C) and cold (30 degrees C) caloric stimulation in either ear of <9 degrees s(-1); or 3) in both ears <15 degrees s(-1). After irrigating the ear with ice water, nystagmus was recorded in the face-up and face-down positions. The result of the test was classified as a response (nystagmus beats away from the irrigated ear in the supine position and changes when in prone), a gravity-independent response (nystagmus does not change in direction in the prone position) or no response. The spontaneous and post head-shaking nystagmus, as well as the results of the head-impulse test, were also analyzed. When indicated, a rotatory chair test was performed.

RESULTS

In the 71 patients that displayed unilateral hypofunction, the ice-water test produced a normal response in 24, a gravity-independent response in 31, and no response in 14. In two of these patients a vertical gravity-independent nystagmus response was observed. Bilateral hypofunction was found in 12 patients and the results in the head-impulse test were in agreement with the results in the ice-water test.