Videonystagmography (VNG) is a procedure that tests inner ear and central motor balance functions. VNG testing is used to determine if a vestibular (inner ear) disease may be causing a balance or dizziness 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 persons 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 45 minutes to 1 hour, and testing is covered by all insurances.
There a 4 main parts to a VNG test:
- Ocular Mobility – You will be asked to have your eyes follow 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.
- 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 ocular 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.
- 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.
- 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.
Reference: National Dizzy and Balance Center