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.
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.
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:
DO NOT stop taking your regular medicines without first talking to your provider.
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.
This test may be used to find the cause of:
It may also be done to look for brain damage in people 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.
If the rapid, side-to-side eye movements do not occur even after ice cold water is given, there may be damage to the:
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.
Reviewed By: Alireza Minagar, MD, MBA, Professor, Department of Neurology, LSU Health Sciences Center, Shreveport, LA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.