Vesticular testing is used to diagnose problems of the inner ear, the portion of the ear responsible for balance. A number of vestibular tests are used to determine whether certain symptoms, such as dizziness, signal an inner-ear disorder.
Videonystagmography (VNG) technologies for testing inner ear and central motor functions. VNG testing is considered the new standard for testing inner ear functions over Electronystagmography (ENG), because VNG measures the movements of the eyes directly through infrared cameras, instead of measuring the mastoid muscles around the eyes with electrodes like the previous ENG version. VNG testing is more accurate, more consistent, and more comfortable for the patient. By having the patient more comfortable and relaxed, consistent and accurate test results are more easily achieved.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 1.5 hours, and testing is covered by all insurances.
For an example of VNG test recording showing a nystagmus click here.
There are 4 main parts to a VNG test:
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
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.
Additional Test that can be performed:
- An electrocochleography is a test in which an electrode is placed over a personâ€™s ear canal to measure the electronic activity of the cochlea, according to the Washington Hospital Center. The cochlea is the portion of the inner ear that is responsible for the transmission of and responses to pressure.
Rotational Chair Test
- The rotational chair test moves patients around in a motorized chair to measure dizziness. According to Dr. Timothy C. Hain, a neurologist who specializes in dizziness disorders, in an article titled â€œVestibular Testing,â€ people with inner-ear diseases are less likely to get dizzy during the test.
- The Mayo Clinic states that during a posturography test, patients stand on a platform and try to maintain their balance. The test is used to show whether the inner ear is responsible for patientsâ€™ balance problems.
- During a fistula test, a doctor uses an instrument called an otoscope to apply pressure to the ear and measure the earâ€™s responses to different pressures. The fistula test can show if a patient has a perilymph fistula, a condition characterized by an abnormal connection between the middle and inner ears, according to an article by Hain titled â€œPerilymph Fistula.â€