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.

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)

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

If nystagmus does not occur after cold or warm water is instilled or there is a difference between the responses of each ear or between cold and warm water response, there may be some damage to the nerve of the inner ear, which controls balance. If nystagmus does not occur even after ice cold water is instilled, permanent damage to the nerve has probably occurred.

Any disease or injury that damages the acoustic nerve can cause vertigo. This may include:

• congenital disorders (present at birth)
• trauma
• rubella
• blood vessel disorders with hemorrhage (bleeding)
• clots
• atherosclerosis of the blood supply of the ear
• cholesteatoma and other ear tumors
• some poisons
• ototoxic (toxic to the ear nerves) medications, including aminoglycoside antibiotics, some antimalarial drugs, loop diuretics, and salicylates

Additional conditions for which the test may be performed:

• acoustic neuroma
• benign positional vertigo
• labyrinthitis
• Meniere's disease