Electronystagmography

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Electronystagmography

Definition:

Electronystagmography records involuntary eye movements. The test is used to determine whether ear nerve damage is the cause of dizziness or vertigo. Damage to the nerve of the inner ear is one of the more common causes of vertigo.

Alternative Names:

ENG

How the test is performed:

Metal electrodes (similar to those used with ECG, but smaller) are placed to the side, above, and below each eye. They may be attached by adhesive or by a band around the head. A "ground" electrode is attached to the forehead. These electrodes record eye movements relative to the position of the ground electrode.

A standard caloric stimulation test is performed, with cold or hot water instilled into the ear canal. Each ear is tested separately. The duration and velocity (speed) of eye movements that occur when the inner ear is stimulated are recorded by the electrodes.

The test takes about 90 minutes. It is performed by an audiologist and interpreted by an ENT specialist.

How to prepare for the test:

No preparation is necessary. Check with your health care provider if you are taking any medications.

How the test will feel:

There is minimal discomfort. You may find cold water in the ear uncomfortable. Brief vertigo may occur during the test.

Why the test is performed:

This test is used to determine if ear nerve damage is a cause of dizziness or vertigo. Damage to the vestibular portion of the acoustic nerve (the nerve of the inner ear) is one of the more common causes of vertigo.

Electronystagmography is performed to evaluate the acoustic nerve, which provides hearing and helps with balance. This test may be recommended when the person is experiencing dizziness or vertigo, when there is impaired hearing, with suspected toxicity from certain antibiotics, and when psychologic causes of vertigo are suspected.

Electronystagmography provides exact measurements of eye movements rather than the objective observation of standard caloric stimulation. It can record behind closed eyelids or with the head in a variety of positions.

Review Date: 4/28/2005
Reviewed By: Chitra R. Uppaluri, M.D., Clinical Assistant Professor of Medicine, Saint Louis University, St. Louis, MO. Review provided by VeriMed Healthcare Network.

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