Sign in  |  Register

Illustrated Health Encyclopedia
[an error occurred while processing this directive]

Ency. home > Test > C > Caloric stimulation

Caloric stimulation   

Overview | Risks | Results

Alternative names:

Caloric test; ENG (electronystagmogram)

Definition:

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 acoustic nerve (the nerve of the inner ear) is one of the more common causes of vertigo.

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 (30 degree C) is instilled in the ear canal with a bulb syringe. This should cause nystagmus. This test is then repeated using warm water (44 degree C). The nystagmus should occur in the opposite direction (towards the warm water then slowly away, rather than away from the water and slowly back). This test is analyzed by the computer for both cold and warm water response for each ear and differences between ears as well as between cold and warm water responses are calculated. Occasionally warm and cold air (in cases with 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

Adults:
Avoid eating a heavy meal before the test. Avoid caffeine, alcohol, allergy medications and sedatives at least 24 hours prior to the test as thay can affect the results. Ask for written instructions from your doctor prior to the test.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

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 impaired hearing, with suspected toxicity from certain antibiotics, with some anemias, when psychological causes of vertigo are suspected, and to determine the presence or extent of brain damage in a comatose person.

Ency. home > Test > C > Caloric stimulation

[an error occurred while processing this directive]