Definition of Electronystagmography:

Electronystagmography is a test to look at voluntary and involuntary eye movements. It evaluates the acoustic nerve, which runs from the brain to the ears (and control hearing and balance) and the occulomotor nerve, which runs from the brain to the eyes.

How the test is performed:

Patches called electrodes (similar to those used with ECG, but smaller) are placed above, below, and to the side of each eye. They may be attached by adhesive or by a band around the head. Another electrode is attached to the forehead.

The electrodes record eye movements that occur when the inner ear and nearby nerves are stimulated by delivering cold and warm water to the ear canal at different times. Sometimes, the test is done using air instead of water. Each ear is tested separately.

When cold water enters the ear, it should cause rapid, side-to-side eye movements called nystagmus. The eyes should move rapidly away from the cold water and slowly back. Next, warm water is placed into the ear. The eyes should now move rapidly toward the warm water then slowly away.

Patients may also be asked to use their eyes to track objects, such as flashing lights.

The electrodes detect the length and speed of eye movements, and a computer records the results.

The test takes about 90 minutes.

Electronystagmography provides exact measurements of eye movements detected by the electrical changes the movements produce. It is more objective than simply watching the eyes after flushing warm or cold water into the ears. It can record behind closed eyelids or with the head in a variety of positions.

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 dizziness (vertigo) may occur during the test.

Why the test is performed:

The test is used to determine whether a balance or nerve disorder is the cause of dizziness or vertigo.

Your doctor may order this test if you have dizziness or vertigo, impaired hearing, or suspected damage to the inner ear from certain medications.