Videonystagmography (VNG) is a test that measures a type of involuntary eye movement called nystagmus. These movements can be slow or fast, steady or jerky. Nystagmus causes your eyes to move from side to side or up and down, or both. It happens when the brain gets conflicting messages from your eyes and the balance system in the inner ear. These conflicting messages can cause dizziness.
You can briefly get nystagmus when you move your head a certain way or look at some types of patterns. But if you get it when you don’t move your head or if it lasts a long time, it may mean you have a disorder of the vestibular system or central nervous system.
The vestibular system is part of the inner ear and is the sensory system that provides a sense of balance and spatial orientation to the brain. Your brain communicates with the different systems in your body to control your balance.