Balance Testing

The balance system is complex and dynamic; it covers a very broad spectrum of motion. Currently, balance testing is only able to evaluate a very narrow spectrum of this complex system. The tests that are available are: audiologic evaluation (hearing test), videonystagmogram (VNG) or electronystagmogram (ENG), rotational chair testing, platform posturography, vestibular evoked myogenic potential (VEMP), and high-pass masked auditory brainstem response audiometry (known as CHAMP testing).           

Audiologic evaluation generates an audiogram, a graphic representation of a person’s hearing levels. Because the inner ear contains both the hearing and balance organs, things that affect the balance part often also affect the hearing part. The type and degree of hearing loss may give clues to the underlying cause of the dizziness.           

In VNG testing, goggles with infrared cameras are placed on a patient. A battery of tests is then performed while the cameras record the patient’s eye movement. Our inner balance system is responsible for coordinating the movement of our eyes when our head moves. By tracking eye movements during head movement, as well as eye movement when the head is placed in certain positions, we are able to determine how well the inner balance system is doing its job. We may also be able to get information about how well the central processor is doing its job. During this test, cold and warm air (or occasionally water) is passed into the ear canal. This will induce vertigo in a person with a normal inner ear. If the inner ear is not responding or is responding less than normal, there will be a lesser response than expected with this testing. The responses of each inner ear may be compared. Electronystagmography (ENG) is the same as VNG, except that instead of wearing goggles, electrodes are placed near the eyes and these electrodes record eye movement.           

In a rotational chair test, the patient is seated in a chair in a small, dark chamber. The chair rotates while the patient is asked to follow and/or focus on a light with his eyes. Electrodes are used to track the patient’s eye movement. Problems with the inner ear will be manifest by a difference in ability of the eyes to track in one direction of rotation when compared to rotation in the other direction. It may also be manifest by a decrease in the eye’s overall ability to track. It is primarily used to detect mild weakness and to monitor the brain’s compensation during recovery.           

Platform posturography is used to assess how well someone has compensated to the inner ear weakness. The patient stands on a platform and is asked to maintain his balance when either the visual clues or the muscle tension clues—or both simultaneously—are removed. It is a tool used mainly by the vestibular therapist to track recovery. VEMP testing and CHAMP testing are valuable to identify which ear is affected by Meniere’s disease. There is a reflexive tightening of one of the muscles of the neck when noise is presented to the ear. This reflex is managed by the inner ear balance system. By recording the muscle response, we can get an idea of how well the balance system is working. CHAMP testing compares the brain’s electrical response to noise in one ear to its response to noise in the other ear. As more invasive treatments are considered for some diseases of the inner ear, it is very important that the problem is localized to the correct ear. At times this is difficult to do. These tests are able to give more specific localization.