Direct answer
Electronystagmography (ENG) records involuntary eye movements (nystagmus) using small electrodes placed around the eyes, to assess how the inner ear balance organs and their brainstem connections are working. ENG helps explain dizziness, vertigo and imbalance. ENG does not image the ear or brain and does not test hearing.
Key takeaways
- ENG measures eye movements, not balance itself, and is one part of a wider dizziness assessment.
- ENG cannot show tumours, strokes, wax-blocked ear drums or hearing loss; imaging and audiometry answer those questions.
- Videonystagmography (VNG) uses infrared cameras instead of electrodes and is now more widely used in many Indian centres.
- Caloric testing commonly causes short-lived spinning and nausea; this is expected, not a complication.
- Results need interpretation alongside your symptoms and examination by the doctor who ordered the test.
At a glance
| Feature | Detail |
|---|---|
| What it records | Eye movements via electrodes around the eyes (electro-oculography) |
| What it assesses | Vestibulo-ocular reflex, spontaneous and positional nystagmus, eye-tracking pathways |
| Typical duration | Around 45-90 minutes including preparation and rest breaks; varies with the battery of subtests performed |
| Anaesthesia | None |
| Discomfort | Temporary dizziness or nausea, mainly during caloric and positional testing |
| Who performs it | Audiologist or trained vestibular technologist; reported with an ENT surgeon or neurologist |
| Does not include | Hearing test, ear imaging, brain imaging |
Also known as
- ENG test
- Nystagmography
- Vestibular function test; "balance test" or "chakkar ki jaanch" in everyday Indian usage
- Caloric test (one component of ENG, not the whole test)
- Closely related but distinct: videonystagmography (VNG)
What electronystagmography is
Electronystagmography is a recording test. Small surface electrodes placed at the outer corners of both eyes, and above and below one eye, pick up the tiny voltage changes that occur as the eyes move. The signals are amplified and traced on a computer.
The inner ear balance organs and the eyes are linked by the vestibulo-ocular reflex, which keeps vision steady when the head moves. If one balance organ is weaker or irritated, this reflex becomes asymmetrical and produces nystagmus, rhythmic, involuntary eye movement. ENG measures the direction, speed and duration of that nystagmus under controlled conditions.
A typical ENG battery includes gaze and spontaneous nystagmus recording, saccade and smooth-pursuit tracking, optokinetic testing, positional and positioning (Dix-Hallpike type) manoeuvres, and bithermal caloric irrigation with warm and cool air or water.
Why electronystagmography is done
- To characterise dizziness: to help distinguish a peripheral (inner ear) pattern from a central (brainstem or cerebellar) pattern.
- To detect and quantify asymmetry: caloric testing can show reduced response on one side, as may occur after vestibular neuritis.
- To support diagnosis: in suspected vestibular neuritis, labyrinthitis, M閚i鑢e's disease, benign paroxysmal positional vertigo (BPPV) and vestibular migraine, alongside clinical findings.
- To assess unexplained imbalance in older adults with falls, where several causes may coexist.
- Before and after certain ear or skull-base procedures, to document baseline function.
- To guide vestibular rehabilitation, by clarifying whether a stable one-sided weakness is present.
Who should get this test
- People with recurrent vertigo, spinning attacks or persistent unsteadiness where the cause is unclear after clinical examination.
- People with suspected one-sided vestibular loss, especially if symptoms are not settling as expected.
- People with imbalance plus hearing changes, tinnitus or ear fullness, usually together with audiometry.
- Older adults with unexplained falls, once blood pressure, medication and vision causes have been considered.
- People being assessed before ear surgery or before starting a structured vestibular rehabilitation programme.
ENG is generally not the first step for a single brief positional vertigo episode that a doctor can diagnose and treat at the bedside, nor for sudden dizziness with neurological signs, where urgent assessment and imaging take priority.
What electronystagmography cannot detect or exclude
- Structural disease: ENG does not visualise the inner ear, vestibular nerve, brainstem or cerebellum. It cannot show or exclude a stroke, acoustic neuroma (vestibular schwannoma), demyelinating lesion or tumour. MRI is required for those questions.
- Hearing: ENG does not measure hearing. Pure-tone audiometry, tympanometry and other audiological tests are separate.
- M閚i鑢e's disease: there is no ENG pattern that confirms or excludes M閚i鑢e's disease; diagnosis remains clinical, based on the pattern of attacks and documented hearing loss.
- BPPV between attacks: positional nystagmus may be absent if the crystals have moved or if the patient has recently performed repositioning exercises. A negative positional test does not mean BPPV is not the cause.
- High-frequency reflex function: caloric irrigation tests only a low-frequency range. Normal calorics do not exclude vestibular dysfunction at higher head velocities; video head impulse testing (vHIT) and rotary chair testing address different frequency ranges.
- Otolith and saccular function: ENG does not assess utricular or saccular function; VEMP testing is used for that.
- Vertical and torsional eye movement: electrode-based recording captures vertical movement poorly and torsional movement not at all, which is a real weakness when assessing posterior-canal BPPV.
- Cause of a compensated loss: an asymmetry on ENG may be an old, healed injury and not the explanation for today's symptoms.
A normal ENG describes what was recorded during the test session. It does not exclude vestibular or neurological disease. If dizziness, imbalance or falls persist or worsen despite a normal report, return to your doctor for reassessment.
Related but different examinations
| Test | Question it answers | How it differs from ENG |
|---|---|---|
| Videonystagmography (VNG) | Same core questions as ENG | Infrared goggle cameras record the eyes instead of electrodes; captures vertical and torsional movement far better; needs the eyes open and visible, so is unsuitable if the eyelids cannot be held open or with certain eye conditions. ENG can still record with eyes closed. |
| Video head impulse test (vHIT) | Is the vestibulo-ocular reflex intact at high head speeds, and which canal is affected? | Quick, well tolerated, no caloric irrigation; tests a different frequency range from calorics. |
| Rotary chair testing | How well does the system respond across a range of rotation frequencies? Useful in children and in bilateral loss | Tests both ears together, so may miss a one-sided difference that calorics would show. |
| VEMP (cervical and ocular) | Are the otolith organs and their pathways working? | Uses sound or vibration with muscle recordings; assesses structures ENG does not. |
| Audiometry | Is hearing affected, and in what pattern? | Hearing only; often essential alongside ENG when M閚i鑢e's disease or labyrinthitis is suspected. |
| MRI brain and internal auditory canals | Is there a structural lesion? | Imaging, not function. Requested when central features, asymmetric hearing loss or progressive signs are present. Implants and devices require MRI safety assessment. |
| Posturography | How well does the person actually maintain balance while standing? | Measures postural control, not eye movement; does not localise the lesion. |
How to prepare
Preparation instructions differ between units and between the subtests planned. Your testing centre's written instructions take precedence over any general advice here.
- Medication list: carry a full list of prescribed and over-the-counter medicines, including AYUSH and herbal products. Sedatives, antihistamines, betahistine, prochlorperazine, antidepressants, anti-epileptics and alcohol can all suppress or alter nystagmus.
- Do not stop any prescribed medicine on your own. If your unit asks for a medicine to be paused before testing, that instruction must come from, or be confirmed by, the doctor who prescribed it.
- Caffeine, nicotine and alcohol: many units ask that these be avoided for around 24-48 hours beforehand.
- Meals: a light meal is usually advised rather than fasting, because caloric testing can provoke nausea. Follow your unit's instruction.
- Eyes and face: avoid eye make-up and facial creams, which interfere with electrode contact. Ask whether to bring spectacles rather than wear contact lenses.
- Ears: tell staff about ear discharge, a perforated eardrum, a grommet, recent ear surgery or heavy wax. Water caloric irrigation is usually avoided with a perforation; air irrigation or an alternative test may be used.
- Getting home: arrange a companion and avoid driving yourself, as unsteadiness can persist for some time.
If you are pregnant
ENG involves no radiation or contrast. Positional manoeuvres and lying flat may be uncomfortable in later pregnancy, and nausea may be more troublesome. Tell the team you are pregnant so positioning can be modified.
Children
Electrode-based ENG and caloric irrigation are often poorly tolerated by young children. Paediatric vestibular assessment is usually done in specialised centres, often using rotary chair or camera-based methods.
Older adults
Neck and spine problems, limited mobility and postural blood pressure drops may restrict some positioning manoeuvres. Tell staff about cervical spondylosis, recent neck or back surgery, or previous vertebral artery problems so the protocol can be adapted.
Diabetes on glucose-lowering treatment
If your unit advises a light meal or any restriction, discuss timing of insulin or tablets with your prescriber beforehand, and bring a fast-acting sugar source. Do not fast for this test on assumption.
Long-standing ear disease, CKD or heart failure
Chronic suppurative otitis media, mastoid cavities and eardrum perforations change how caloric testing can be done. If you have heart failure, advanced chronic kidney disease or a fluid restriction, tell staff, prolonged lying flat and repeated position changes may need to be paced, and any fluid instruction should be checked against your prescribed restriction.
What happens during electronystagmography
The skin around the eyes is cleaned and electrodes are taped in place with a small amount of conductive gel. A calibration recording is taken while you follow a light or dot with your eyes.
The session then usually moves through several parts. You may be asked to track a moving target, hold your gaze in different directions, keep the eyes closed while mental tasks are given, and lie or turn into set head and body positions. In caloric testing, warm and then cool air or water is delivered into each ear canal in turn for a short period, and the resulting eye movement is recorded. This part commonly produces a strong spinning sensation for around a minute, sometimes with nausea. Staff will tell you when it is about to start and will give rest breaks between irrigations.
How long does the process take
Most complete ENG batteries take around 45-90 minutes, including electrode placement, calibration and recovery breaks. A shortened protocol focused only on positional testing may be quicker. Allow extra time afterwards, as some people remain unsteady for a while and need to sit before travelling.
Understanding your report
An ENG report describes recorded eye movement patterns rather than giving a single number. It is a functional description that must be read together with your history, ear examination and hearing results.
- Spontaneous or gaze-evoked nystagmus: present or absent, with direction. Direction-fixed nystagmus suppressed by visual fixation suggests a peripheral pattern; direction-changing, purely vertical or fixation-resistant nystagmus raises concern about a central cause.
- Saccades, smooth pursuit, optokinetic responses: abnormalities here point towards central pathways rather than the inner ear, but can also reflect poor attention, drowsiness, medication or age.
- Positional and positioning tests: the report notes whether a manoeuvre provoked nystagmus, its latency and duration.
- Caloric results: reported as a side-to-side difference (canal paresis) and a directional preponderance. Laboratories use their own cut-offs, so interpret only against the reporting laboratory's stated limits.
Terms such as "reduced caloric response on the left" describe measurement, not diagnosis. The same finding can mean a recent inner ear infection, an old compensated injury, or a technical artefact. Only your treating doctor can place it in context. Results vary depending on individual clinical circumstances.
When results can be misleading
Responses falsely reduced or absent
- Sedatives, antihistamines, vestibular suppressants, alcohol, anti-epileptics and some antidepressants dampen nystagmus.
- Drowsiness, poor alertness or eyes drifting during closed-eye recording.
- Wax occluding the canal, or a mastoid cavity changing heat transfer, so the caloric stimulus never properly reaches the balance organ, this can mimic a weak ear.
- Air irrigation is generally a weaker and more variable stimulus than water.
- Visual fixation not adequately removed, which suppresses genuine peripheral nystagmus.
Responses falsely raised or abnormal-looking
- Electrode drift, poor skin contact, dried gel, sweating or eye make-up producing artefact.
- Blinking, muscle tension, anxiety and voluntary eye movement mimicking nystagmus.
- Mains electrical interference in the recording.
- Congenital nystagmus or long-standing squint, which is unrelated to current vestibular symptoms.
- Recent caffeine or nicotine, and uncorrected refractive error affecting tracking tasks.
Structural limits of the method
Because electrode recording captures torsional eye movement poorly, posterior-canal BPPV can be under-recognised on ENG compared with camera-based VNG. A negative positional result should be read with that in mind.
Risks and safety
ENG is non-invasive and uses no radiation, contrast or needles. Risk differs by component, so it should not be described with a single safety statement.
Electrode recording
Mild skin redness or irritation from tape or gel can occur. Tell staff about adhesive allergies or skin conditions around the eyes.
Positional and positioning manoeuvres
Brief, sometimes intense vertigo and nausea are common. There is a small risk of neck or back strain, and manoeuvres may be modified or avoided with significant cervical spine disease, recent neck or spinal surgery, or unstable cardiac or vascular problems.
Caloric irrigation
Marked spinning, nausea and occasional vomiting are expected in many people. Water irrigation is generally avoided if the eardrum is perforated, if a grommet is in place or after recent middle-ear surgery, because of infection risk. Unsteadiness may last from minutes to a few hours, so plan not to drive.
Optokinetic and tracking tests
Usually well tolerated. People with photosensitive epilepsy or migraine sensitive to visual stimuli should inform staff beforehand.
Red flags
Emergency now
- Sudden vertigo with slurred speech, facial or limb weakness, numbness, double vision or difficulty swallowing.
- Sudden severe headache or neck pain with dizziness, or an inability to sit or walk unaided.
- Vertigo with chest pain, breathlessness, fainting or a persistently very fast or irregular pulse.
- Head injury followed by vertigo, vomiting, drowsiness or clear fluid from the ear or nose.
These need emergency assessment, not an ENG appointment. Vestibular testing does not exclude stroke.
Same day
- Sudden one-sided hearing loss with vertigo.
- New ear pain, discharge or fever with dizziness.
- Vertigo with persistent vomiting and inability to keep fluids down.
- First ever severe vertigo attack, or a fall causing injury.
Routine appointment
- Recurrent short positional spinning episodes that settle between attacks.
- Gradual unsteadiness, motion sensitivity or a feeling of being off-balance.
- Long-standing tinnitus or ear fullness with occasional dizziness.
- Reviewing an ENG report and planning vestibular rehabilitation.
Electronystagmography in the Indian context
- Terminology: patients commonly describe symptoms as "chakkar" or giddiness. It helps to say whether the room spins, whether you feel faint, or whether you feel unsteady on walking, these point to different causes and change which test is useful.
- Chronic ear disease: chronic suppurative otitis media and eardrum perforation remain common in India and directly affect whether water caloric irrigation can be used safely. Mention any history of ear discharge or ear surgery when booking.
- Anaemia and blood pressure: iron-deficiency anaemia and postural blood pressure drops are frequent contributors to giddiness and are not detected by ENG. Basic blood tests, blood pressure measurement and medication review often need to be done alongside.
- Medication effects: vestibular suppressants and antihistamines are widely available over the counter in India and are often taken for weeks before testing, which can blunt ENG findings. Declare all of these, including AYUSH preparations.
- Ototoxicity: aminoglycoside exposure, including injectable antibiotics used in some treatment settings, can cause bilateral vestibular loss. Mention past prolonged injectable antibiotic courses.
- Availability: full vestibular laboratories are concentrated in larger cities and teaching hospitals. Many centres now offer VNG rather than classical electrode-based ENG; ask which is being performed, since the reports are not interchangeable in every respect.
- Data: reports and any online forms are personal health data; handling is governed by the Digital Personal Data Protection Act, 2023.
Cost and insurance in India
Charges for ENG or VNG vary widely between cities, between government and private centres, and with the number of subtests performed. Costs are usually quoted per session, and related tests such as audiometry, VEMP, vHIT or MRI are billed separately.
Factors that affect cost:
- City and type of facility (government, trust, standalone audiology clinic, corporate hospital).
- Whether classical ENG or camera-based VNG is used, and the equipment generation.
- Number of subtests, a focused positional study costs less than a full battery with bithermal calorics.
- Whether audiometry, tympanometry, VEMP or vHIT are bundled into the same visit.
- Specialist consultation and reporting charges.
- Package deals for pre-surgical or vestibular rehabilitation assessment.
Insurance: as an outpatient diagnostic test, ENG is often not covered under standard indemnity health policies unless linked to an admission or covered by an OPD rider. Cover may apply if testing forms part of an admitted episode or a planned surgical work-up. Confirm with your insurer or the hospital's insurance desk before the appointment, and ask for a written estimate.
Myths and facts
| Myth | Fact |
|---|---|
| A normal ENG means nothing is wrong. | ENG samples a limited part of balance function. Vestibular migraine, BPPV between attacks, high-frequency vestibular loss and central conditions can all occur with a normal ENG. |
| ENG will find the cause of any giddiness. | Many causes of giddiness, low blood pressure, anaemia, medication effects, cardiac rhythm problems, anxiety, lie outside what ENG measures. |
| ENG is a scan of the inner ear. | ENG is a functional recording of eye movement. It produces no images and cannot replace MRI or CT. |
| ENG tests hearing too. | Hearing requires separate audiological testing. |
| The test is dangerous because it makes you dizzy. | Provoked dizziness is the intended effect of caloric and positional testing and is usually short-lived, though it can be unpleasant. |
| ENG and VNG are the same test. | They answer similar questions by different means, and differ meaningfully in what eye movements each can record. |
| You must stop all dizziness medicines before ENG. | Some may need pausing, but only on the advice of the prescribing doctor. Stopping medicines without advice can be harmful. |
Frequently asked questions
Will the ENG test hurt?
Electrode placement is painless. The uncomfortable part for most people is the provoked spinning and nausea during caloric and positional testing, which usually lasts under a minute per irrigation. Staff pace the test and give rest breaks. Tell them immediately if you feel sick or unable to continue.
Can I go to work or drive after ENG?
Plan not to drive yourself. Unsteadiness, mild nausea or fatigue can persist from a few minutes to a few hours after caloric testing. Many people prefer to rest for the remainder of the day, particularly if their work involves heights, machinery or driving.
Should ENG or VNG be done?
That depends on your symptoms and on what the centre has available. VNG records vertical and torsional eye movement better, which helps in positional vertigo. Classical ENG can record with the eyes closed, useful when eyelids cannot be held open. Your specialist will choose.
Does a reduced caloric response on one side mean permanent damage?
Not necessarily. A side-to-side difference may reflect recent inflammation that will partly recover, an old injury the brain has already compensated for, or a technical problem such as wax or a mastoid cavity altering the stimulus. Interpretation needs your history and examination.
Can ENG diagnose M閚i鑢e's disease?
No single ENG finding confirms M閚i鑢e's disease. Diagnosis rests on the pattern of vertigo attacks, fluctuating hearing loss documented on audiometry, tinnitus and ear fullness. ENG may show a caloric asymmetry, but this supports rather than establishes the diagnosis.
Is ENG safe if my eardrum is perforated?
Electrode recording and positional testing are generally unaffected. Water caloric irrigation is usually avoided with a perforation, grommet or recent middle-ear surgery because of infection risk; air irrigation or an alternative test may be substituted. Tell staff about any ear discharge or ear surgery in advance.
Can children have ENG?
Young children often tolerate electrodes and caloric irrigation poorly. Paediatric vestibular testing is usually done in specialised centres using rotary chair, camera-based or shortened protocols, with a parent present. Your paediatric ENT team will advise what is suitable by age and cooperation.
How soon will I get the report?
Traces are recorded during the session, but interpretation is not immediate. Reporting timelines differ between units, so ask the centre when you book and whether a specialist review appointment is needed to discuss the findings alongside your hearing tests.
Do I need an MRI as well?
Sometimes. MRI is considered when there are central features, asymmetric or sudden hearing loss, progressive symptoms or neurological signs, because ENG cannot show structural lesions. Your doctor decides based on your examination, not on the ENG result alone. Metal implants require MRI safety assessment.
Sources
- B醨醤y Society, International Classification of Vestibular Disorders, diagnostic criteria for BPPV, M閚i鑢e's disease, vestibular migraine and vestibular neuritis.
- American Academy of Otolaryngology-Head and Neck Surgery Foundation, clinical practice guideline on benign paroxysmal positional vertigo.
- American Academy of Audiology and British Society of Audiology, practice guidance on vestibular assessment and caloric testing.
- Standard otolaryngology and neuro-otology reference texts on vestibular function testing.
