Videonystagmography (VNG) is a test that measures a type of eye movement that you can’t control. These eye movements are called nystagmus. With nystagmus, your eyes move from side to side, up and down, or in a circle. The movements can be slow or fast, steady or jerky.
Normally, nystagmus happens briefly as your eyes adjust when you move your head into certain positions. If it happens at other times or doesn’t happen when it should, you may have a disorder of the balance system in your inner ear. This balance system is called the vestibular system.
Good balance partly depends on the organs and nerves in your vestibular system working together with your vision and the muscles in your neck and eyes. When everything is working properly, your brain gets the information it needs to keep your eyes focused on an object when your body changes position. This helps you keep your balance when you are moving.
Problems with certain parts of your balance system can cause nystagmus, which may make you feel dizzy or unsteady. If you’re having symptoms of a balance problem, VNG can help find out if a vestibular disorder is causing your symptoms.
Other names: VNG
What is it used for?
VNG is used to find out if you have a disorder of the vestibular system (the balance system in your inner ear). It can also help find problems with the nerves or parts of your brain that are part of your sense of balance.
Why do I need a VNG?
You may need a VNG if you have symptoms of a vestibular disorder. The main symptom is dizziness. Dizziness means different things to different people. It can include:
- Vertigo, a feeling that you or everything around you is spinning
- Feeling as if you’re going to fall
- Feeling lightheaded or as if you are going to faint
Other symptoms of a vestibular disorder may include:
- Ringing in your ears (tinnitus)
- Feeling of fullness or pressure in your ear
What happens during a VNG?
A VNG is usually done by a specialist, such as:
- An audiologist, a health care provider who is trained to diagnose hearing loss and balance disorders. Audiologists can also provide certain treatments to improve these conditions.
- An otolaryngologist (ENT), a doctor who specializes in treating diseases of the ears, nose, throat, and head and neck.
- A neurologist, a doctor who specializes in diagnosing and treating disorders of the brain and nervous system
During a VNG test, you’ll sit in a dark room wearing special goggles. A camera in the goggles will record your eye movements during these three main parts of the test:
- Ocular testing. Without moving your head, you will follow moving lights with your eyes and stare at steady lights.
- Positional testing. You’ll be asked to move your head and body into different positions. The provider will also move your head into certain positions. Your eyes will be checked to see if certain movements cause nystagmus.
- Caloric testing. For this part of the VNG, your ears will be tested one at a time. This can show if the vestibular system in one ear is working better than the other. Cool water or air will be put into your ear. The cool temperature should make your eyes move in specific ways. You will be tested again with warm water or air in the same ear. If your eyes don’t move as expected, it may mean you have damage in your inner ear or the part of your brain that controls balance.
Will I need to do anything to prepare for a VNG?
Your provider will let you know how to prepare for your test. You may need to avoid certain foods or medicines before your test. But don’t stop taking any medicine without talking with your provider first.
Are there any risks to a VNG?
The test may make you feel dizzy for a few minutes. You may want to plan to have someone bring you home in case the dizziness lasts longer. Some people have nausea for a short time during caloric testing, but vomiting is uncommon.
What do the results mean?
If your VNG results were not normal, it may mean you have a disorder of the vestibular system in your inner ear. The disorder may be in one or both ears. Your provider can explain what type of disorder you may have. You may need more tests, including other balance tests, to confirm your diagnosis.
A VNG can help diagnose several vestibular disorders, including:
- Benign paroxysmal positional vertigo (BPPV). BPPV is the most common cause of vertigo in adults. With this condition, you feel a spinning sensation when you move your head in certain ways. Normally, part of your inner ear has grains of calcium that help tell your brain about your head’s position and movement. BPPV happens if these grains slip out of place and get into a part of your inner ear where they don’t belong. When the grains move around in the wrong place, they trigger confusing signals about how your head is moving.
- Meniere’s disease. This disorder causes vertigo, hearing loss, tinnitus (ringing in the ears), and a full feeling in your ears. It happens when too much fluid builds up in the vestibular system. The cause is unknown.
- Labyrinthitis. This balance disorder can cause dizziness and temporary hearing loss. It happens if parts of your inner ear become irritated and inflamed (swollen), usually from a cold or flu. It sometimes goes away on its own.
- Vestibular neuritis. This is irritation and inflammation (swelling) of the vestibular nerve. This nerve carries signals from the vestibular system in your inner ear to your brain. It’s usually caused by a viral infection. The main symptoms are nausea and vertigo./li>
- Acoustic neuroma. This is a tumor which develops on the nerves involved with hearing and balance. It’s usually benign (not cancer), but it can cause hearing loss, tinnitus, and/or dizziness.
An abnormal VNG result may also mean you have a condition that affects the parts of your brain that help control your balance. Treatment options depend on the type of balance disorder you have.
If you have questions about your results or treatment, talk with your provider.
Is there anything else I need to know about a VNG?
Another test, called electronystagmography (ENG), measures the same type of eye movements as a VNG. Instead of using a camera to record eye movements, an ENG measures eye movements with electrodes placed near your eyes. The electrodes are small sensors that either stick to your skin or are put in a headband that you wear.
ENG testing is still useful in certain cases. For example, it may be a good test for people with eyelids that partly covert their pupils or for people who feel anxious about wearing goggles. But VNG testing is more common and more accurate. It is also quicker to do, but more costly.
Courtesy of MedlinePlus from the National Library of Medicine.