Quick answer: A caloric test examines the low-frequency response of each horizontal vestibular system separately. Warm and cool air or water is introduced into the ear canal while VNG goggles record eye movements. Brief vertigo or nausea can occur, but the response is monitored and usually settles after each stimulation.
Before the appointment: tell the clinic about ear surgery, a perforated eardrum, ear discharge, severe neck/back limitations, pregnancy, migraine sensitivity and all medicines. Do not stop prescribed medication unless the testing service specifically instructs you to do so.
What the caloric test is designed to do
The inner ears help the brain detect head movement. During caloric testing, warming or cooling the ear canal creates a controlled temperature gradient near the horizontal semicircular canal. This produces a predictable vestibular signal and reflex eye movement called nystagmus.
Because the right and left ears are stimulated separately, the test provides information that many natural head-movement tests do not. It is one part of a vestibular assessment and is not a stand-alone diagnosis.
How to prepare
- Follow the laboratory’s written instructions about food, drink and medicines.
- Bring a complete medicine list, including sleep, allergy, nausea, anxiety and migraine medicines.
- Avoid alcohol before the test and arrive rested where possible.
- Do not wear eye makeup if the service asks you not to; it can interfere with VNG tracking.
- Bring previous hearing, imaging, VNG or vestibular reports if available.
- Arrange someone to accompany you if you are prone to severe nausea or prolonged dizziness.
Instructions differ between laboratories. If a medicine is medically important, ask before withholding it. An incomplete medicine change is safer than stopping essential treatment without advice.
What happens during the appointment
- Ear and history check: the clinician reviews symptoms and checks for factors that may change the procedure.
- Positioning: you lie back with the head supported in the required angle.
- VNG recording: goggles or cameras record eye movements, often in darkness.
- Separate ear stimulation: warm and cool stimulation is delivered to one ear at a time.
- Response period: you may be asked simple questions to stay alert while the eye movement is recorded.
- Recovery: the clinician waits for the response to settle before the next irrigation or before you sit up.
A standard bithermal protocol commonly involves four main stimulations—warm and cool for each ear—but the exact method, temperature, duration and use of air or water depend on the laboratory protocol and clinical situation.
What the patient may feel
Temporary spinning, warmth or coolness in the ear, nausea, sweating or a sensation that the room is moving can occur. These symptoms reflect the intended vestibular stimulation and do not by themselves mean that the inner ear is damaged.
Tell the clinician promptly if you have severe pain, panic, marked nausea or another concerning symptom. The test can be paused. Most people need a short rest afterward; a minority feel unsettled for longer.
When the method may be changed or postponed
Active ear discharge, certain perforations, recent ear surgery, obstructing wax, inability to position safely or a medical condition that makes strong vertigo unsafe can affect testing. Water irrigation is not appropriate for every ear. The clinician may use air, modify the protocol, perform another test or postpone the appointment.
Caloric testing also has technical limitations. Ear anatomy, poor goggle recording, alertness, medicines and incomplete thermal transfer can influence the response. These factors should be documented rather than converted directly into a diagnosis.
After the caloric test
- Sit up slowly and wait until you feel steady.
- Ask for help walking if residual dizziness remains.
- Do not drive until you feel fully recovered and the testing service says it is appropriate.
- Eat and drink according to your usual medical advice after the test.
- Contact the clinic if severe or unusual symptoms persist.
This guide intentionally does not teach detailed interpretation. For terms such as unilateral weakness, directional preponderance and caloric–vHIT disagreement, read how caloric test results are interpreted. For the broader role of eye-movement recording, see the VNG test guide.
Frequently asked questions
Does a caloric test hurt?
It should not be painful, although ear stimulation can feel unusual and temporary dizziness or nausea can occur.
Why are the ears tested separately?
Separate stimulation helps the clinician compare each ear under controlled conditions.
Can I take vertigo medicine before the test?
Do not stop prescribed medicine on your own. Follow the laboratory instructions because some medicines can affect eye movements or symptoms.
What if I have a perforated eardrum?
Tell the clinic before testing. The clinician may change the stimulation method, postpone the test or choose another assessment.
Where are caloric result terms explained?
Use the linked companion guide for unilateral weakness, directional preponderance, fixation suppression and comparison with vHIT.
Reference
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice, diagnosis or prescribing guidance. Consult Dr. Prateek Porwal at Prime ENT Center, Hardoi for personalised treatment.
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