Videonystagmography (VNG)

What is a VNG?

Videonystagmography (VNG) is designed to test inner ear and central motor functions. VNG testing is considered the new standard for testing inner ear functions over Electronystagmography (ENG), this is due to the fact that a 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 considered to be more accurate, consistent, and comfortable for the patient. Due to these facts, a superior test is more easily achieved.

When is an VNG used?

VNG testing is used to determine if a vestibular (inner ear) disease may be causing a balance or dizziness problem. A VNG test is one of the only tests available today that can decipher between a unilateral (one ear) and bilateral (both ears) vestibular loss. VNG testing is a series of tests designed to document a person's ability to follow visual objects with their eyes and how well the eyes respond to information from the vestibular system.

This test also addresses the functionality of each ear and if a vestibular deficit may be the cause of a dizziness or balance problem. To monitor the movements of the eyes, infrared goggles are placed around the eyes to record eye movements during testing. VNG testing is non-invasive, and only minor discomfort is felt by the patients during testing as a result of wearing goggles. Appointments usually last about 1.5 hours, and testing is covered by all insurances.

What Does a VNG Test Entail?

A VNG test consists of four parts. These parts include:
  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 is the only test available that can decipher between both unilateral and bilateral hearing loss.

What sensations am I going to experience during a VNG?

You may become weak, dizzy, or nauseated during a videonystagmogram. 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 a videonystagmogram 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.

How to Prepare for this Test

The test will take about 1 hour, occasionally a little longer.

Please dress comfortably and wear clothes that will not be affected by possible contact with water.

Do not wear eye make-up. This interferes with the infra-red cameras in the goggles as they try and track your eye movement.

Please continue to take heart, high blood pressure, thyroid, diabetes, anti-seizure, and anticonvulsant medications. Questions about other medications should be discussed with your doctor.

Some medications or substances influence the body's response to this test and can result in useless or even false test findings.

The following medications must not be taken for 72 hours prior to the test.

  • Aspirin
  • Alcohol in any quantity and from any source, including beer, wine, and cough medicines containing alcohol
  • Anti-nausea medications, including Dramamine, Compazine, Bonine, Marezine, Phenergan, Thorazine, etc
  • Anti-vertigo medication, including Antivert, Meclizine, etc.
  • Tranquilizers, including Valium, Librium, Atarax, Vistaril, Equanil, Miltown, Triavil, Serax, Etrafon, etc.
  • Sedatives, including Nembutal, Seconal, Dalmane, Doriden, Placidyl, Qualude, Butisol, or any other sleeping pills
  • Narcotics and Barbiturates, including Phenobarbital, Codeine, Demerol, Benadryl, Actifed, Teldrin, Triaminic, any over-the-counter cold remedies, etc.
  • Antihistamines, including Chlortrimeton, Dimetane, Disophrol, Benadryl, Actifed, Teldrin, Triaminic, or any over-the-counter cold remedies, etc.
  • Quinine

Avoid all caffeine and caffeinated drinks 24 hours prior to your test. This is to include coffee, tea, soda or any beverage containing caffeine or alcohol and caffeinated foods like chocolate.

Do not eat or smoke for 3 hours before the test.