VNG Testing

Videonystagmography (VNG) Test for Dizziness, Vertigo & Vestibular

Overview and Purpose

For individuals having difficulties with their balance and equilibrium, videonystagmography (VNG) is a valuable diagnostic procedure that is simple and painless, and it can help more accurately determine the cause of your dizziness symptoms. VNG testing is considered the new standard for testing inner ear functions over Electronystagmography (ENG), because VNG measures the movements of the eyes directly through infrared cameras, instead of measuring the mastoid muscles around the eyes with electrodes like the previous ENG version. VNG testing is more accurate, more consistent, and more comfortable for the patient. By having the patient more comfortable and relaxed, consistent and accurate test results are more easily achieved.

If dizziness is not caused by the vestibular portion of the inner ear, it might be caused by the brain, by medical disorders such as low blood pressure, or by psychological problems such as anxiety. VNG is a test used to determine whether or not dizziness may be due to inner ear disease.

Dizziness: Lightheadedness or Vertigo?

Dizziness is often used to describe either lightheadedness or vertigo, so it is important to know the difference in symptoms to help narrow down the list of possible problems.

Vertigo the illusion that you or your surroundings are moving (spinning, leaning, falling) without actual movement. Severe vertigo can cause nausea and even lead to vomiting. Physically you may lose your balance or have trouble walking. Vertigo is not the same as motion sickness because no repeated motion is triggering the feeling.

Lightheadedness is the sensation of almost fainting or passing out, but without the feeling your surroundings are moving. Lightheadedness often disappears while lying down. When lightheadedness gets worse it can feel like almost fainting and may sometimes feel nauseating to the point of vomiting. It is not uncommon to sometimes feel lightheaded and it is usually is not caused by a serious problem, i.e. it could be a momentary drop in blood pressure from getting up too quickly from being seated or lying down.

Dizziness is a generic term that covers all abnormal symptoms of balance and stability.

Imbalance is a person’s inability to maintain balance – especially when standing.

Parts of VNG Testing

There are four main parts of the VNG testing.

  1. Occular Mobility 
    You will be asked to have your eyes follow objects that jump from place to place, stand still, or move smoothly. The technician will be looking for any slowness or inaccuracies in your ability to follow visual targets. This may indicate a central or neurological problem, or possibly a problem in the pathway connecting the vestibular system to the brain.
  2. Optokinetic Nystagmus
    You will be asked to view a large, continuously moving visual image to see if your eyes can appropriately track these movements. Like the occular mobility tests, the technician will be looking for any slowness or inaccuracies in your ability to follow visual targets. This may indicate a central or neurological problem, or possibly a problem in the pathway connecting the vestibular system to the brain.
  3. Positional Nystagmus 
    The technician will move your head and body into various positions to make sure that there are no inappropriate eye movements (nystagmus), when your head is in different positions. This test is looking at your inner ear system and the condition of the endolymph fluid in your semi-circular canals. The technician is verifying that small calcium carbonate particles called otoconia are not suspended in the fluid and causing a disturbance to the flow of the fluid.
  4. Caloric Testing 
    The technician will stimulate both of your inner ears (one at a time) with warm and then cold air. They will be monitoring the movements of your eyes using goggles to make sure that both of your ears can sense this stimulation. This test will confirm that your vestibular system for each ear is working and responding to stimulation. This test in the only test available that can decipher between a unilateral and bilateral loss.

Important Instructions For VNG Testing

To ensure the most accurate VNG results, it is important to observe the following:

How is the VNG Test done?

The test uses a camera to trace quick eye movements (or nystagmus) in response to certain visual cues and positional changes. This information is illuminating because there are neural pathways that connect the balance mechanism of the inner ear to the muscles of the eye. A disorder of the balance mechanism can result in quick eye movements that can only be detected with advanced optics.

In our testing, a camera attached to a pair of goggles worn by the patient records eye movement as the patient looks back and forth between designated points, tracks moving lights, and moves the head and body into different positions in a dark room.

A final portion of the test involves the insertion of cool and warm air into the ear to determine if the balance system is responding predictably to temperature stimulation. Because the hearing and balance functions of your inner ear are so closely related, we routinely administer a hearing test before VNG to assess the condition of this system.

Risks?

The test will likely cause some dizziness, though this is critical for measuring your physiological response to the symptom. This generally passes within a few minutes. It’s a good idea to make arrangements for someone to drive you home in the unlikely event of prolonged dizziness. Expect your test to take approximately 60–90 minutes.

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Alabama Clinics: 334-712-1170
We accept all major insurances including Medicaid, Medicare, Aetna, and Bluecross.