Vertigo is the sensation of spinning or whirling that results from a disturbance in your balance system, and may be used to describe feelings of dizziness.
Videonystagmography assesses the function of the vestibular portion of the inner ear for those experiencing symptoms of dizziness and other balance disorders. A series of hearing evaluation tests are frequently combined with vestibular studies to identify inner ear disorders.
Videonystagmography (VNG) evaluates the functionality of each ear and identifies whether or not a vestibular deficit may be the cause of a dizziness or balance problem. VNG testing is recognized as the new standard for testing inner ear functions over Electronystagmography (ENG), because VNG measures the movements of the eyes directly through infrared cameras, as opposed to measuring the mastoid muscles around the eyes with electrodes like the previous ENG method.
VNG testing has proven to be more accurate and consistent, as well as more comfortable for patients. When patients are comfortable and relaxed, testing is more likely to yield consistent and accurate test results. VNG is a non-invasive procedure, but some patients do experience minor discomfort from wearing infrared goggles during the test. These goggles are placed around the eyes to record and monitor eye movements during testing. Patients can expect these appointments to last 1.5 hours in duration.
There are 4 main parts to a VNG test:
- Occular Mobility – The patient will be asked to use their eyes to follow objects that jump from place to place, move slowly, or don’t move at all. The technician will observe and identify any slowness or inaccuracies in the patient’s ability to follow visual targets. If identifications are made, this could indicate a central or neurological problem or a complication in the pathway that connects the vestibular system to the brain.
- Optokinetic Nystagmus – The patient will be asked to view a large, continuously moving the visual image to see if their eyes can appropriately track these movements. The technician will observe any slowness or inaccuracies in your ability to follow visual targets. These identifications could indicate a central or neurological problem, or possibly a complication in the pathway connecting the vestibular system to the brain.
- Positional Nystagmus – This test observes a patient’s inner ear system and the condition of the endolymph fluid in the semi-circular canals. The patient’s head and body are moved into different directions and positions to assess whether or not there are inappropriate eye movements (called nystagmus) when the head is in different positions. The technician then verifies that small calcium carbonate particles called otoconia are not suspended in the fluid, causing a disturbance to the flow of the fluid.
- Caloric Testing – Warm water and cold air are instilled into both of the patient’s inner ears. This test confirms whether or not a patient’s vestibular system for each ear is working and responding to stimulation. Technicians are monitoring the movements of the eyes using goggles to determine if one ear reacts differently from the other, indicating an inner ear weakness. Caloric Testing is the only procedure available that can decipher between a unilateral and bilateral loss.