What is a VNG?
VNG testing is used to determine if a balance disorder originates inside or outside of the inner ear , and is one of the only tests available today that can decipher between a unilateral (one ear) and bilateral (both ears) damage to the balance system (vestibular system). 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’s center of balance and if the inner ear’s vestibular organ of balance 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. A unique movement of the eyes called nystagmus may appear with vestibular disorders affecting equilibrium.
You can see an example of nystagmus below.
Since there are complex connections between the balance center and the centers controlling the movement of the eyes, the test consists of four main parts:
1. Occular 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.
2. Optokinetic Nystagmus
2. 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.
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 in the only test available that can decipher between a unilateral and bilateral loss.
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.
You may experience brief episodes of dizziness during some portions of the test. A physician will interpret your test results, correlate it with other clinical findings, and report the findings to you.
Certain substances that affect the Central Nervous System (CNS) can influence your response to this test. Therefore you must refrain from certain medications and alcohol (including beer, wine, and mixed drinks) for 48 hours before testing. There is a partial list of medications on the following page which need to be held for 48 hours before testing.
DO NOT refrain from LIFE SUSTAINING MEDICATIONS! If you have any questions about medications that you are currently taking, please call our office for clarification. In addition, please refrain from eating for 4 hours before testing.
IF YOU ARE DIABETIC, DO NOT ALTER YOUR CURRENT DIET OR DIABETIC MEDICATION REGIMEN.
Please wear comfortable clothing. Due to the sensitive nature of the infra red goggles used for testing, patients are prohibited from wearing eye and facial make-up (including eyeliner, eye shadow, mascara and false eye lashes). Contact lenses are permissible. You may be asked to remove any earrings.