Videonystamography (VNG) is a test that measures a type of involuntary eye movement called nystagmus. Depending on whether these eye movements are fast, steady, or erratic, a practitioner can gain a better understanding on whether the patient has a disorder of the vestibular system. VNG testing can be very instrumental in uncovering what could be causing a patient’s dizziness and vertigo.
How is a VNG Test Performed?
A VNG test should be performed in a dark room with a VNG system. This includes a pair of VNG goggles, a screen that displays eye movements captured by the goggles’ cameras, and a computer with software that can save the test results.
There are three main parts to a VNG test:
Ocular Mobility
The ocular mobility test checks for a patient’s ability to follow visual targets, such as a moving light on a bar. The patient will follow targets with their eyes while an object is jumping, moving slowly, or standing still. Difficulty or inability to track objects could indicate central or neurological problems or an issue with the vestibular system.
Optokinetic Nystagmus
A patient’s ability to follow visual targets is measured with this test. The patient will watch an image that is continuously moving. Optokinetic nystagmus testing will also give clues to possible central or neurological problems or problems with the vestibular system.
Positional Testing
Here the practitioner moves the patient’s head and body in different positions using techniques like the Epley and Dix-Hallpike maneuvers. Performing these positional tests on patients can help determine which movements causesnystagmus.
Caloric Testing
During this part, warm and cool water or air are inserted into the patient’s ears. Cold water or air entering the inner ear should cause nystagmus. The eyes should move in the opposite direction ofthe ear receiving the cold water and then slowly move back to center. On the contrary, warm water should cause the eyes to move slowly toward the ear receiving the water and then slowly back to center. If neither happens, it may indicate damage to the nerves of the inner ear.
What Disorders Can VNG Testing Help Diagnose?
A VNG examination can help uncover if the patient has any of the following disorders:
Benign Paroxysmal Positional Vertigo (BPPV)
BPPV is one of the most common causes of vertigo. It causes brief episodes of mild to intense dizziness and is usually triggered by changes in head position. While BPPV can drastically affect quality of life, it's seldom serious except when it increases the chance of falls.
Meniere's Disease
A debilitating disorder that causes dizziness, bouts of hearing loss, and tinnitus. Most of the time, it affects only one ear, and in rare cases, it affects both. There is no cure for Meniere's disease, but it can be managed with vestibular rehabilitation, medicine, and/or dietary changes.
Labyrinthitis
This disorder that causes vertigo and imbalance. It occurs when part of the inner ear becomes infected or swollen. Sometimes labyrinthitis resolves on its own.Other times, antibiotics may be necessary to help control infection.
Choosing the Right Equipment
Having the right equipment is critical to ensuring the success of your VNG testing program. You want to ensure you have a high-quality VNG system that you can rely on to provide accurate results. e3 carries a wide variety of VNG systems, as well as other instruments used in vestibular assessment. Check out our website today to learn more about our vestibular testing technologies!
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