Videonystagmography (VNG)
Videonystagmography (VNG) is a diagnostic test that measures involuntary eye movements to identify disorders within the vestibular system, which controls balance.
What is videonystagmography (VNG)?
VNG measures nystagmus, a type of involuntary eye movement where the eyes move side to side, up and down, or in a circle. While nystagmus can occur normally when adjusting to head movement, its presence at other times may indicate a disorder of the vestibular system—the balance system located in your inner ear.
Why do I need a VNG?
You may need a VNG if you experience symptoms of a vestibular disorder, primarily dizziness. Dizziness can manifest as:
- Vertigo: A sensation that you or your surroundings are spinning.
- Feeling as if you are going to fall.
- Feeling lightheaded or faint.
Other symptoms may include tinnitus (ringing in the ears) or a feeling of fullness/pressure in the ear.
What happens during a VNG?
The test is typically performed by an audiologist, an otolaryngologist (ENT), or a neurologist. You will wear special goggles equipped with a camera to record eye movements during three phases:
- Ocular testing: Following moving lights and staring at steady lights without moving your head.
- Positional testing: Moving your head and body into various positions to see if they trigger nystagmus.
- Caloric testing: Introducing cool or warm water/air into each ear to test the vestibular system's response.
What do the results mean?
An abnormal VNG result may indicate a vestibular disorder in one or both ears. Common conditions diagnosed via VNG include:
- Benign paroxysmal positional vertigo (BPPV): Caused by calcium grains shifting in the inner ear.
- Meniere's disease: A buildup of fluid in the vestibular system.
- Labyrinthitis: Inflammation of the inner ear, often following a cold or flu.
- Vestibular neuritis: Inflammation of the vestibular nerve, usually due to a viral infection.
- Acoustic neuroma: A typically benign tumor on the nerves involved in hearing and balance.
The test may also identify conditions affecting the parts of the brain that control balance.