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Caloric stimulation

Contents of this page:

Alternative Names   

Caloric test; Cold water calorics; Warm water calorics

Definition    Return to top

Caloric stimulation is a test which uses differences in temperature to diagnose ear nerve damage.

How the Test is Performed    Return to top

This test stimulates the inner ear and nearby nerves by delivering cold and warm water to the ear canal at different times. Rarely, the test is done using air instead of water. The person doing the test should examine the ear and especially the eardrum to make sure it is normal before doing the test.

One ear is tested at a time.

When cold water enters the ear and the inner ear changes temperature, it should cause rapid, side-to-side eye movements called nystagmus. The eyes should move away from the cold water and slowly back.

Next, warm water is placed into the ear. The eyes should now move towards the warm water then slowly away.

The eyes can be observed visually, but more often this test is done as part of electronystagmography which uses patches called electrodes, placed around the eyes, to detect the movements. A computer records all the results.

Ice cold water may be used if there are no responses.

How to Prepare for the Test    Return to top

Do not eat a heavy meal before the test. Avoid caffeine, alcohol, allergy medications, and sedatives at least 24 hours prior to the test, as these can affect the results. (However, do not stop taking medicines without first talking to your doctor.)

How the Test Will Feel    Return to top

Some people find cold water in the ear uncomfortable. Brief, but severe vertigo may occur during the test. You may have nausea associated with that feeling. Vomiting is rare.

Why the Test is Performed    Return to top

Caloric stimulation is done to check the acoustic (ear) nerve, which provides hearing and helps with balance. It is also used to test parts of the brain involved in balance.

This test may be recommended if you have:

It may also be done to look for brain damage in persons in a coma.

Normal Results    Return to top

Rapid, side-to-side eye movements should occur when cold or warm water is placed into the ear. The eye movements should be similar on both sides.

What Abnormal Results Mean    Return to top

Abnormal results mean there may be damage to the nerve of the inner ear. If the rapid, side-to-side eye movements do not occur even after ice cold water is given, there may be damage to the nerve, the balance sensors of the inner ear, or the brain.

Abnormal results may be due to:

The test may also be done to diagnose or rule out:

Risks    Return to top

Excessive water pressure can injure a previously damaged eardrum, but this rarely occurs since the amount of water to be used is measured in advance. Caloric stimulation should not be performed if the eardrum is perforated because of the risk of causing ear infection. Caloric testing should not be performed during an acute vertigo episode as it can make symptoms worse.

Considerations    Return to top

Caloric stimulation is approximately 80% accurate in differentiating nerve damage as a cause of vertigo. Other tests may be required to confirm the diagnosis.

References    Return to top

Baloh R. Hearing and equilibrium. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 454.

Update Date: 3/26/2009

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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