Electronystagmography (ENG)

What is electronystagmography?

Electronystagmography (ENG) is a test to examine how well certain nerves in your brain are working. It analyzes the nerves that control your eye movements, hearing and balance. Your healthcare provider may order an ENG if you have a suspected or diagnosed disorder that affects your sense of balance.

What nerves does an ENG test?

An ENG looks for rapid involuntary eye movements called nystagmus. It also tests the health of four cranial nerves:

• Oculomotor nerve, which connects your eye muscles to your brain and controls eye movements.
• Trochlear nerve, which connects your eye muscles to your brain and helps you look toward or away from your nose.
• Abducens nerve, which connects your eye muscles to your brain and helps you look away from your nose in the horizontal plane.
• Vestibular nerve,which connects your inner ear to your brain and controls balance and hearing.

When would an ENG be needed?

Your healthcare provider may order an ENG if you have symptoms of inner ear problems like:

• Balance problems.
• Dizziness and forms of vertigo.
• Unexplained hearing loss.

You may also have an ENG during diagnosis or treatment for conditions like:

• Acoustic neuroma.
• Benign paroxysmal positional vertigo (BPPV).
• Labyrinthitis or vestibular neuritis.
• Ménière’s disease.
• Usher syndrome.

What is the difference between ENG and VNG?

An ENG involves placing small metal discs (electrodes) around your eyes. A videonystagmography (VNG) uses special goggles and infrared cameras. ENGs assess the strength of eye muscles, while VNGs assess eye movements. They give healthcare providers similar information about your nerves and inner ear function.

Who performs an ENG?

Usually, an audiologist performs an ENG. Audiologists are doctors who specialize in hearing and balance disorders.

How do I prepare for an electronystagmography?

Your healthcare provider will give you specific instructions to prepare for an electronystagmography. Typically, you don’t need to do anything special.

Tell your healthcare provider about all medications or supplements you take. They may instruct you to stop taking certain medications, like sedatives or antivertigo medications, for 24 to 48 hours before the test.

How is an ENG test done?

An ENG test uses small metal discs called electrodes. Your healthcare provider attaches the electrodes above, below and near the outer corner of each eye. You also have one electrode on your forehead. The electrodes may be attached to a headband that you wear. Or they may be separate sticky patches.

You sit in a dark exam room during an ENG. The patches record your eye movements in different scenarios like:

1. Putting cold and warm water or air into each ear to stimulate your vestibular nerve.
2. Keeping your head still while following a light with your eyes to stimulate your oculomotor and trochlear nerves.
3. Turning your head or sitting up quickly to stimulate your oculomotor, trochlear and vestibular nerves.

ENG tests usually last around 90 minutes.

What can I expect after an ENG?

You can typically return home and resume usual activities on the day of the test. You may feel dizzy or nauseated for a brief period during the test. These symptoms usually go away that same day.

What are the risks of an ENG?

ENGs are low-risk tests. You may have some back or neck pain because of the quick movements of an ENG. Most people don’t have any severe complications from the test.

Rarely, high water pressure in your ear canal may injure your eardrum. Your healthcare provider may avoid putting water in your ear if you recently had a hole (perforation) in your eardrum.

What do the results of an ENG mean?

If your eyes don’t move as expected during an ENG, it could point to cranial nerve damage. Cranial nerve damage can occur for several reasons, including:

• Blood vessel disorders.
• Cholesteatoma.
• Medicines such as certain antimalarial drugs, diuretics or antibiotics.
• Movement disorders.
• Multiple sclerosis.
• Rubella.
• Traumatic injuries.

If your ENG results show irregular eye movements, your healthcare provider may order more diagnostic tests. Follow-up and treatment depend on the underlying cause of the irregular eye movements or nerve damage.

A note from Cleveland Clinic

An electronystagmography (ENG) is a test to measure your eye movements and check the health of your cranial nerves. It involves placing electrodes around your eyes, which measure your nerve function. Your healthcare provider may send a small burst of warm or cold air into your ears during the test. You might also move your head in specific ways or follow flashes of light with your eyes. ENGs that show atypical eye movements could point to issues with one or more of your cranial nerves. Your healthcare provider will determine if follow-up tests are needed and appropriate treatment.