What is electronystagmography?
Your healthcare provider can use
electronystagmography (ENG) to evaluate vertigo and certain other hearing and vision
disorders. Vertigo is a false sense of spinning or motion that can cause dizziness.
eyes and sense of vision are a major part of your sense of balance.
For this test, your healthcare provider places electrodes above and
below the eye. The electrodes record electrical activity of the muscles that control
movement. An ENG measures the changes in the electrical field within the eye. An ENG
then find uncontrolled (involuntary) rapid eye movement (nystagmus) in response to
certain stimuli. If this eye movement does not occur when stimulated, you may have
problem within the ear. Or you may have a problem with the nerves that supply the
or certain parts of the brain.
The ENG is actually a series of
tests that may include 1 or more of the following measurements:
- Calibration test. For this test, you
follow a light with your eyes. This test checks for ocular dysmetria, a condition
that causes the pupils to overshoot their target.
- Gaze nystagmus test. For this test,
you stare at a fixed light placed to either the center or the side as you are seated
or lying down. This test measures how well you can fix your gaze at an object without
your eyes moving involuntarily.
- Pendulum-tracking test. For this
test, you follow a light with your eyes as it moves like a clock's pendulum.
- Optokinetics test. This checks your
ability to follow a light. The light moves quickly across and out of your field of
vision and back again while you keep your head still.
- Positional test. For this test, you
move your head and perhaps your whole body, not just your eyes. For example, you may
be told to turn your head quickly to one side. Or you may be asked to sit up quickly
after you have been lying down. The amount of eye motion that results from this
activity is recorded.
- Water caloric test. This test places
warm or cool water into the ear canal with a syringe. The water touches the tympanic
membrane. If no problem exists, your eyes will move involuntarily to this stimulus.
Your provider may use air instead of water as the stimulus for this test. This is
more likely if you have a damaged tympanic membrane.
Why might I need an ENG test?
Your healthcare provider uses ENG to find disorders of the peripheral vestibular system,
the parts of the inner ear that interpret balance and spatial orientation, or the
nerves that connect the vestibular system to the brain and the muscles of the eye.
You may have this test if you have unexplained dizziness, vertigo, or hearing loss.
These are symptoms, not a diagnosis. The ENG may help find the exact cause of your
symptoms. Possible causes include:
- Acoustic neuroma. A tumor of the nerve that
controls sound and balance.
- Labyrinthitis. Inflammation of the inner ear, often
caused by a virus.
- Usher syndrome. A congenital disorder that causes
- Ménière disease. This is when you have too much
fluid in the inner ear. It can affect hearing and balance.
If a known sore (lesion) exists, an
ENG can find the actual site. There may be other reasons for your healthcare provider
recommend an ENG.
What are the risks of an ENG test?
There are very few risks with ENG. Some people may have dizziness or nausea during
ENG should not be used if you have
a pacemaker. The equipment may interfere with pacemaker function.
The quick changes in position
needed for the test may make back or neck problems worse.
The water caloric test may
cause mild discomfort. If you have been previously diagnosed with a perforated tympanic
membrane, you should not have the water caloric part of the ENG test.
There may be other risks depending
on your specific health condition. Discuss any concerns with your healthcare provider
before the procedure.
Certain factors or conditions may interfere with ENG. These include:
- Impaired vision
- Frequent blinking
- Certain medicines, such as sedatives, tranquilizers, and anti-vertigo medicines
How do I get ready for an ENG test?
- Your healthcare provider will explain
the procedure to you and you can ask any questions that you might have about the
- You may be asked to sign a consent
form that gives your permission to do the procedure. Read the form carefully and ask
questions if something is not clear.
- Follow any directions you are given
for not eating or drinking before the test.
- Tell your healthcare provider of all
medicines (prescribed and over-the-counter), vitamins, and herbal supplements that
- Stop taking sedatives, tranquilizers,
and any other medicines as instructed by your healthcare provider before the
- Carefully clean your ears of excessive
earwax. Before the ENG, your ears will be checked for wax, inflammation, or other
problems that may interfere with the test.
- If you wear \lasses or a hearing aid,
bring them with you to the test.
- Based on your health condition,
your healthcare provider may request other specific preparation.
What happens during an ENG test?
You may have an ENG on an
outpatient basis. This means you go home the same day. Or it may be done as part of
hospital stay. Procedures may vary depending on your condition and your healthcare
Generally, the ENG follows this process:
- Your healthcare provider will remove any wax in your ear.
- Before placing the electrodes, your
healthcare provider will clean areas of the skin on your face with an
alcohol-saturated cotton pad and let them air dry.
- Your provider will use a paste to
attach the electrodes. He or she will place an electrode in the center of your
forehead. Another electrode will be placed above the eyebrow and below the eye. You
will still be able to close your eyes. You may also have electrodes on the side of
- Depending on the type of test being
done, you may be asked to look up, down, or to the side. Or you may be asked to move
your head or entire body. You may also be asked to close your eyes. This won't
interfere with recording your eye movement.
- For caloric testing, your provider
will put either air or water into the ear. This is done while recording your eye
- A recorder detects the electrical
activity from the electrodes. The recorder amplifies the signal and charts so that
your provider can interpret the results.
What happens after an ENG test?
Once the test is done, your
provider will remove the electrodes and wash off the electrode paste. Don't rub your
eyes to prevent spreading the electrode paste.
Your provider will watch you for
any signs of weakness, dizziness, and nausea. You may need to lie down or sit for
minutes to recover.
Your healthcare provider will tell
you when to start taking any medicines you stopped taking before the test.
Your healthcare provider may give
you other instructions after the procedure, depending on your particular situation.
You may also have a videonystagmography (VNG). This is a test that
also detects eye movement. But it uses video cameras instead of electrodes.
Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure