Background:
Videonystagmogram (VNG) technology is a test used to examine the inner ear and central motor functions. VNG testing is considered the new standard for testing inner ear functions over and measures the movements of the eyes directly through infrared cameras. This test also addresses the functionality of each ear and if an inner ear disease may be the cause of a dizziness or balance problem.
Why is The Test Performed?
VNG testing is used to determine if a vestibular (inner ear) disease may be causing dizziness, room spinning sensation or balance problem, and 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.
How is the test performed?
The main part of the VNG testing include:
1- Occular Mobility
You will be asked to have your eyes follow certain 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. Some people refer to this as “crystals” in the ears.
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 a unilateral and bilateral loss.
Test preparation:
There is no specific test preparation. The study is very short in duration. The patient generally will be ready to go home immediately following the test.
