CALORIC TEST normal values

Timothy C. Hain, MD • Page last modified: February 21, 2021

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The caloric test is a part of the ENG. It is an attempt to discover the degree to which the vestibular system is responsive and also how symmetric the responses are, between left and right ears. It is a test of the lateral semicircular canals alone -- it does not assess vertical canal function or otolithic function. While not as good as we would like, the caloric test is the best that we have to deduce the function of each ear independently of the other.

Computations involved in the Caloric test: (see this page for the main procedure)

The main value derived from caloric testing is the peak slow-phase velocity, for each side and each temperature (i.e. 4 values). Four numbers are obtained -- cold right, cold left, warm right, and warm left. Spontaneous nystagmus (SN) should be subtracted from these, and then the absolute value taken. From these responses, LC, LW, RC, RW, three additional numbers are derived:

If spontaneous nystagmus is not subtracted off first, peculiar results may appear, such as greater than 100% paresis (which is obviously impossible).

Normal values for caloric tersting:

There is considerable test-retest variability. The upper limits for test-retest variation for paresis were found by Proctor et al to be 24%. The upper limits for DP was 22%. This suggests that upper limits of normal should be set at greater than these values, which do not take into account variability of the normal population, and are therefore inappropriately low.

Although difficult to decode due to presentation of logarithmically transformed data, the paper by Sills, Baloh et al. 1977 has considerable useful data concerning caloric parameters.

Effects of Age on Caloric testing. Very little.

According to Peterka et al (1990), "Caloric test parameters showed no consistent trend with age." This was also the opinion of Mallinson and Longridge, who stated "Our experiment confirms that slow phase velocity of caloric responses does not decline with age."

Karlsen et al (1981) reported a small decrease in the peak slow phase velocity, from 27.35 in individuals aged 18-35, and 25.95 in persons aged 71 and greater.

Maes et al (2010) found "increasing slow-component velocity values" with the caloric test with age. Their data (like all caloric studies) showed immense scatter and we suspect this finding was just due to insufficient power.

Mulch and Petermann reported middle aged persons had higher responses, but their study was done using older technology and we think that the newer papers should be favored as being more accurate.

References: