Caloric stimulation

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Caloric stimulation

Definition:

Caloric stimulation is a test which uses differences in temperature to diagnose ear nerve damage as a cause of dizziness or vertigo. Damage to the vestibular portion of the nerve of the inner ear (acoustic nerve) is a common cause of vertigo.

Alternative Names:

Caloric test

How the test is performed:

Each ear is tested separately using a computerized caloric stimulation machine. Nystagmus (quick movement of both eyes in response to certain stimuli, which is necessary for normal vision and balance) is measured using electrodes around the eye and recorded for analysis by the computer.

Cold water is placed in the ear canal with a bulb syringe. This should cause nystagmus. This test is then repeated using warm water. The nystagmus should occur in the opposite direction (towards the warm water then slowly away, rather than away from the water and slowly back).

The computer analyzes:

The cold and warm water response for each ear
Differences between ears
Differences between cold and warm water responses

Occasionally, warm and cold air (if there is a hole in the ear drum) or ice cold water (in absence of any response) is used for this test.

How to prepare for the test:

Avoid eating 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. Ask for written instructions from your doctor prior to the test.

For infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

There is minimal discomfort. Some people find cold water in the ear uncomfortable. Brief, but severe vertigo may occur during the test.

Why the test is performed:

Caloric stimulation is performed to evaluate the acoustic nerve, which provides hearing and helps with balance.

This test may be recommended:

when someone is experiencing dizziness or vertigo
when there is hearing loss with suspected toxicity from certain antibiotics
with some anemias
when psychological causes of vertigo are suspected
to determine the presence or extent of brain damage in a comatose person

Review Date: 4/11/2005
Reviewed By: Kevin Fung, MD, FRCS(C), Department of Otolaryngology, Division of Head and Neck Oncology and Reconstructive Surgery, University of Western Ontario, Londong, Ontario, Canada. Review provided by VeriMed Healthcare Network.

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