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Caloric stimulation
Caloric test; Bithermal caloric testing; Cold water calorics; Warm water calorics; Air caloric testing
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.
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:
- Before the test, your ear, especially the eardrum, will be checked. This is to make sure it is normal.
- One ear is tested at a time.
- A small amount of cold water or air is gently delivered into one of your ears. Your eyes should show an involuntary movement called nystagmus. Then they should turn away from that ear and slowly back. If water is used, it is allowed to drain out of the ear canal.
- Next, a small amount of warm water or air is gently delivered into the same ear. Again, your eyes should show nystagmus. Then they should turn toward that ear and slowly back.
- Your other ear is tested in the same 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 .
Electronystagmography
Electronystagmography is a test that looks at eye movements to see how well two nerves in the brain are working. These nerves are:Vestibular nerve (...
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:
- Alcohol
- Allergy medicines
- Caffeine
- Sedatives
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.
Vertigo
Dizziness is a term that is often used to describe 2 different symptoms: lightheadedness and vertigo. Lightheadedness is a feeling that you might fai...
Why the Test is Performed
This test may be used to find the cause of:
- Dizziness or vertigo
- Hearing loss that may be due to certain antibiotics or other drugs
It may also be done to look for brain damage in persons who are in a coma .
Coma
Decreased alertness is a state of reduced awareness. A coma is a state of decreased alertness from which a person cannot be awakened. A long-term co...
Normal Results
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 the:
- Nerve of the inner ear
- Balance sensors of the inner ear
- Brain
Abnormal results may be due to:
- Poor blood supply to the ear
- Bleeding (hemorrhage)
- Blood clot
- Brain or brain stem damage
-
Cholesteatoma
Cholesteatoma
Cholesteatoma is a type of skin cyst that is located in the middle ear and mastoid bone in the skull.
Read Article Now Book Mark Article - Birth defects of the ear structure or brain
- Damage to the ear nerves
- Poisoning
-
Rubella
that damages the acoustic nerve
Rubella
Rubella, also known as the German measles, is an infection in which there is a rash on the skin. Congenital rubella is when a pregnant woman with rub...
Read Article Now Book Mark Article - Trauma
The test may also be done to diagnose or rule out:
-
Acoustic neuroma
Acoustic neuroma
An acoustic neuroma is a slow-growing tumor of the nerve that connects the ear to the brain. This nerve is called the vestibular cochlear nerve. It...
Read Article Now Book Mark Article -
Benign positional vertigo
Benign positional vertigo
Benign positional vertigo is the most common type of vertigo. Vertigo is the feeling that you are spinning or that everything is spinning around you...
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Labyrinthitis
Labyrinthitis
Labyrinthitis is irritation and swelling of the inner ear. It can cause vertigo and hearing loss.
Read Article Now Book Mark Article -
Meniere disease
Meniere disease
Ménière disease is an inner ear disorder that affects balance and hearing.
Read Article Now Book Mark Article
Risks
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.
Ear infection
Otitis is a term for infection or inflammation of the ear.
References
Baloh RW, Jen JC. Hearing and equilibrium. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 428.
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: 2/3/2015
Reviewed By: Amit M. Shelat, DO, FACP, Attending Neurologist and Assistant Professor of Clinical Neurology, SUNY Stony Brook, School of Medicine, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
