Hearing & balance
VNG and caloric testing
Eye-tracking goggles and the warm-and-cool ear test - the classic core of the balance laboratory.
Key facts
At a glance
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VNG: infrared goggles record eye movements during gaze tasks, head positioning and movement - painless observation.
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Caloric testing: warm and cool water or air in each ear canal stimulates the balance organ, deliberately producing brief, mild vertigo.
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Why the dizziness is the point: the provoked response measures how strongly each ear’s balance organ answers - identifying a weak side.
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Preparation: no alcohol for 24-48 hours, vestibular sedatives paused, light meal only, minimal eye make-up.
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Follow-up: results quantify one-sided weakness and positional nystagmus, guiding rehabilitation or repositioning treatment.
The full picture
What this test involves, and how to get it
Videonystagmography (VNG) uses infrared cameras mounted in light-proof goggles to record the eye movements that the inner ear generates - the involuntary drift-and-flick pattern called nystagmus that betrays vestibular imbalance. The recording session moves through structured stages: following targets to test central eye control, positional manoeuvres including the Dix-Hallpike test that provokes BPPV’s unmistakable response, and finally caloric testing - the venerable core of the laboratory. Warm and then cool water or air is run gently into each ear canal, creating a temperature gradient that stimulates the horizontal canal; each ear’s response strength is measured through the nystagmus it produces. A significantly weaker response on one side is objective evidence of that ear’s deficit.
Honesty about the experience: caloric testing deliberately makes you dizzy for a minute or two per ear - a genuinely strange sensation that settles fully and is, in fact, the measurement itself working. The preparation rules exist because alcohol, sedatives and anti-dizziness medication all suppress the responses being measured. Caloric results remain the reference standard for unilateral weakness, complementing the newer vHIT test which assesses different frequencies of head movement. Testing is available through NHS audiovestibular departments after ENT or GP referral, with waits varying widely; private balance laboratories typically offer appointments within one to three weeks, reporting to an ENT surgeon or audiovestibular physician who translates side and severity into treatment.
A quiet reminder
This guide is for information, not medical advice.
Your own clinician knows your history and can tell you which parts apply to you. Next review of this page: 2027-09-27.
Frequently asked
Common questions about VNG and caloric testing.
Quick, plain-English answers to what people ask us most.
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What is VNG and caloric testing?
VNG and caloric testing is a diagnostic test used to look at a specific part of the body or how it is functioning, helping doctors reach a clear diagnosis. It is usually requested when symptoms, an examination finding, or an earlier test result needs further investigation. Your doctor can explain exactly why it has been suggested in your case.
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Why would a doctor order VNG and caloric testing?
Doctors typically request this test to confirm or rule out a suspected condition, investigate unexplained symptoms, or monitor something that has already been diagnosed. It gives more detailed information than a standard examination alone can provide. The result helps guide what treatment or further investigation, if any, is needed.
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Do I need to prepare for VNG and caloric testing?
Preparation requirements vary by test; some need no special preparation, while others ask you to avoid caffeine, certain medications, or strenuous exercise beforehand. You will normally be given specific instructions when the appointment is confirmed. If anything is unclear, it is best to check directly with the clinic beforehand.
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What happens during VNG and caloric testing?
You will be asked to carry out a series of simple, guided steps - such as breathing into a device, lying still while readings are taken, or performing light activity - while equipment records the relevant measurements. The person carrying out the test will explain each stage as you go. Most appointments are completed within a single visit.
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Does VNG and caloric testing hurt or carry risks?
These tests are generally safe and non-invasive, with little to no discomfort involved. Any risks are usually minimal and will be explained to you before the test if relevant. Tell the team if you have any concerns so they can address them directly.
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How long do results take?
Results are usually reported by a specialist within a few days, though this can vary depending on the complexity of the test and whether further analysis is needed. You will normally be told when and how to expect your results at the time of booking. Urgent findings are typically flagged and communicated more quickly.
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What do abnormal results mean, and what happens next?
An abnormal result does not automatically mean something serious - it simply indicates that further assessment may be needed. Your doctor will review the findings in the context of your symptoms, history, and any other test results before recommending next steps, which might include further investigation, referral to a specialist, or reassurance that no action is needed. Always discuss your specific results with a doctor rather than interpreting them alone.
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Is VNG and caloric testing available privately, or should I wait for the NHS?
VNG and caloric testing can usually be arranged privately, often within days, with results reviewed by a specialist rather than waiting for routine NHS scheduling, which can take considerably longer depending on local demand. Cost varies by provider, and many private providers accept both self-referral and GP or specialist referral. Your GP can also advise on the appropriate NHS pathway if you would prefer to wait.
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Is VNG and caloric testing accurate and reliable?
This is a well-established test used routinely in clinical practice, and when performed and interpreted by an experienced specialist it is generally considered reliable. As with any test, results are always interpreted alongside your symptoms and medical history rather than in isolation. Occasionally a test may need to be repeated or supplemented with further investigation for a fully clear picture.
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How do I book VNG and caloric testing privately, and how quickly can I be seen?
You can typically book privately with or without a GP referral, and appointments are often available within a matter of days. A specialist reviews and reports the results, with a clear explanation of what they mean and any recommended next steps.