An electronystagmogram (ENG) measures
involuntary rapid eye movements called nystagmus and evaluates the muscles
controlling eye movements. ENG evaluates how well the eyes, inner ears,
and brain help you maintain balance and a sense of position (such as when
changing from lying down to a standing position).
ENG is done to help determine whether
damage to the structures or nerves in the inner ear or brain is causing
dizziness or vertigo.
Nystagmus occurs normally when the
head is moved. However, spontaneous or prolonged nystagmus may be associated
with certain conditions that affect the nerves or structures of the inner
ear or brain.
During ENG, electrodes are attached
to the face near the eyes to detect eye movements. The signals from the
electrodes are recorded on graph paper. ENG involves a series of recordings.
Baseline readings are taken with the
head at rest.
Additional readings are taken:
Why It Is Done
While the head is moved in different
positions (up and down, left and right).
While looking at a moving object.
After warm or cold water (or air) is
placed inside the ears.
An electronystagmogram (ENG) is done
How To Prepare
Determine a possible point of origin
for dizziness or vertigo.
Locate, determine the extent, and monitor
the progress of damage to structures or nerves in the inner ear or brain.
Evaluate hearing loss in one ear (unilateral)
with unknown cause.
Before the test, you will be asked
to stop taking:
Your health professional may advise
you to eat only a light meal or not eat for several hours before the procedure,
because the procedure may cause nausea and vomiting. Do not wear facial
makeup during the test because it can interfere with attaching the electrodes
to the skin.
Medications that reduce vertigo.
Sedatives and tranquilizers.
Drinks containing alcohol.
Stimulants, including foods that contain
caffeine (such as coffee, tea, cola, and chocolate).
If you normally wear glasses, contact
lenses, or hearing aids, bring them to the test. If you have a neck or
back condition, tell your health professional before the test so that precautions
can be taken to prevent worsening of your problem.
How It Is Done
Before testing begins, your eyes
and ears will be examined. Any earwax blocking your ear canal will be removed.
Five electrodes will be attached
with an adhesive to the skin of your face. You will be tested while seated
in a darkened room. The test may have up to six parts.
Toward the end of the test, your eye
movements may be monitored while cool and warm water is placed inside your
ears. In some cases, warm and cool air may be blown gently into your ears
instead of using water. This part of testing is called the caloric test
and may be done without using electrodes to detect the eye movements. The
caloric test is not done if you have a perforated eardrum, because water
used in the caloric test can get into the middle ear and lead to infection.
To determine the proper settings for
the measuring instrument, you will follow a moving point of light with
only your eyes. You should not move your head during this part of the test.
Readings will be taken while your eyes
are closed. You may be given a mental task to do (such as an arithmetic
problem) during this part of the test. Also, readings will be taken while
you gaze straight ahead and to each side.
Readings will be taken while your eyes
follow the back-and-forth movement of a pendulum.
Readings will be taken while you follow
a series of moving objects out of your line of vision. As each object leaves
your line of vision, you will be asked to look immediately at the next
Readings will be taken while you move
your head from side to side and up and down. You may be asked to move your
body (as well as your head) into different positions.
Testing may take up to 90 minutes.
How It Feels
You may become weak, dizzy, or nauseated
during an electronystagmogram. You may feel as though you are going to
fall down during testing. Care will be taken to make sure that you do not
fall. The effects of the test are temporary.
The level of discomfort caused by
an electronystagmogram depends on the reason for having the test. If you
are having the test done due to periods of dizziness or vertigo, you may
find that the test causes your condition to worsen temporarily.
During the caloric testing, you
may feel nauseated and may vomit. You may need to lie down until the nausea
and vomiting or vertigo pass.
An electronystagmogram may cause
vomiting. There is a slight risk of causing a neck or back condition to
worsen because of the quick body movements that are done during the test.
If you have a neck or back condition, tell your health professional before
the test so that precautions can be taken to prevent worsening of your
An electronystagmogram (ENG) is a
test that measures involuntary rapid eye movements called nystagmus. ENG
evaluates how well the eyes, inner ears, and brain help you maintain balance
and a sense of position (such as when changing from lying down to a standing
position). Results are recorded as normal or abnormal.
Test results are normal if there
are no abnormal involuntary eye movements during testing. Normally, some
nystagmus may be expected with head-turning.
Results of the caloric test are
normal if involuntary eye movements have normal direction and intensity.
Test results are abnormal if there
is prolonged nystagmus or vertigo with head-turning. The results of the
caloric test are abnormal if there are decreased eye movements or an absence
of eye movements. Abnormal results may:
What Affects The Test
Identify and locate some kinds of brain
damage or damage to nerves or structures in the ear that affect balance.
Suggest a stroke, Méniere’s disease,
otosclerosis, multiple sclerosis, or labyrinthitis.
Factors that can interfere with your
test and the accuracy of the results include:
What To Think About
Some medications, such as stimulants
(including caffeine), depressants, sedatives, and medications to relieve
Excess movements of the head or other
movements, such as blinking,
The inability to cooperate and focus.
Medical conditions that affect attention, poor eyesight, and excessive
sleepiness can affect test results.
At some health care facilities, you
cannot have an electronystagmogram if you have a pacemaker because the
instrument that measures the eye movements can affect pacemaker function.
The caloric test creates an abnormal
situation that the ear would not normally experience. In some cases, this
can make the results difficult to interpret.
Because an electronystagmogram cannot
detect some inner ear problems, a normal result does not completely rule
out an inner ear condition.
To evaluate hearing loss or tinnitus,
other tests, such as audiometry may be done. If a tumor or stroke is suspected
in a certain part of the brain, a CT scan or MRI scan may be used to confirm
Author: Jan Nissl, RN, BS
Primary Medical Reviewer: Renee
M. Crichlow, MD – Family Medicine
Specialist Medical Reviewer: Colin
Chalk, MD, CM, FRCPC – Neurology