Caloric stimulation is a test that uses differences in temperature to diagnose damage to the acoustic nerve. This is the nerve that is involved in hearing and balance. The test also checks for damage to the brain stem.
Caloric test; Bithermal caloric testing; Cold water calorics; Warm water calorics; Air caloric testing
How the Test is Performed
This test stimulates your acoustic nerve by delivering cold or warm water or air into your ear canal. When cold water or air enters your ear and the inner ear changes temperature, it should cause fast, side-to-side eye movements called nystagmus. The test is done in the following way:
During the test, the health care provider may observe your eyes directly. Most often, this test is done as part of another test called electronystagmography.
How to Prepare for the Test
Do not eat a heavy meal before the test. Avoid the following at least 24 hours before the test, because they can affect the results:
But do not stop taking your regular medicines without first talking to your doctor.
How the Test will Feel
You may find the cold water or air in the ear uncomfortable. You may feel your eyes scanning back and forth during nystagmus. You may have vertigo, and sometimes, you can also have nausea.This lasts only a very short time. Vomiting is rare.
Why the Test is Performed
This test may be used to find the cause of:
It may also be done to look for brain damage in persons who are in a coma.
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
If the rapid, side-to-side eye movements do not occur even after ice cold water is given, there may be damage to:
Abnormal results may be due to:
The test may also be done to diagnose or rule out:
Too much water pressure can injure an already damaged eardrum. This rarely occurs because the amount of water to be used is measured.
Water caloric stimulation should not be done if the eardrum is torn (perforated). This is because it can cause an ear infection. It also should not be done during an episode of vertigo because it can make symptoms worse.
Baloh RW, Jen J. Hearing and equilibrium. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 436.
Kerber KA, Baloh RW. Neuro-otology: diagnosis and management of neuro-otological disorders. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 37.
Review Date: 3/22/2013
Reviewed By: Ashutosh Kacker, MD, BS, Associate Professor of Otolaryngology, Weill Cornell Medical College, and Associate Attending Otolaryngologist, New York-Presbyterian Hospital, New York, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.
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