Vestibular Testing

The purpose of the ENG is to determine whether or not dizziness may be due to inner ear disease. There are four main parts to the ENG. The calibration test evaluates rapid eye movements. The tracking test evaluates movement of the eyes as they follow a visual target. The positional test measures dizziness associated with positions of the head. The caloric test measures responses to warm and cold water circulated through a small, soft tube in the ear canal.

The ENG test is the gold-standard for diagnosis of ear disorders affecting one ear at a time. For example, the ENG is excellent for diagnosis of vestibular neuritis. The ENG is also useful in diagnosis of BPPV and bilateral vestibular loss, although the rotatory chair test is better at the diagnosis of bilateral vestibular disorders than is the ENG. The calibration and tracking tests are intended to diagnose central nervous system disorders, such as cerebellar degenerations. These tests are generally insensitive compared to an examination by a neurologist or an MRI scan. ENG, however, is much less expensive than an MRI in most institutions.

When dizziness or vertigo occurs, the first thing many sufferers do is report it to their physician. He or she will usually obtain detailed information about the dizziness, including when it began, what seems to bring it on (or make it worse or better), exactly what sensations are experienced and specific medical information.
Since the balance organs are located in the inner ear, a hearing evaluation is recommended, typically followed by an electronystagmography test, or ENG.

Although the balance organs are located in the inner ear, the entire balance system includes the brain, brainstem, eyes and sensory nerves throughout the body. When a person becomes dizzy, an involuntary eye movement occurs. This eye movement is called "nystagmus". By stimulating the entire balance system and carefully measuring this nystagmus, your audiologist can help your physician to determine what is, or is not, causing your dizziness. ENG is the recording and measurement of eye movements.

To complete the ENG, electrodes first are taped and pasted onto the skin around the eyes. The nystagmus is recorded in response to different eye, head and body positions. Testing is also performed to evaluate dizziness caused by movement. The last part of the ENG test occasionally causes patients to experience some dizziness. Warm and cool air (or water) is introduced to the ear canals to stimulate each balance organ independently to compare their function.

The audiologist reports the pattern of normal and abnormal eye movements during each of these tests to the patient’s physician. In some types of dizziness, a simple 20-minute treatment, called canalith repositioning, can result in dramatic improvement — or even complete elimination — of symptoms.
Dizziness is not normal. If you experience regular or constant dizziness or loss of balance, consult your audiologist or physician immediately

Videonystagmography (VNG)
Videonystagmography (VNG) is performed similarly to the Electronystagmogrpahy; however, the testing is performed using video imaging technology. Hi-tech video goggles with infrared cameras record the nystagmus and display it on a screen with the test recordings. The same test parameters are followed with the goggles that were originally recorded by electrodes while undergoing the ENG.
(videonystagmography) is a complete diagnostic system for recording, analyzing and reporting eye movements using video imaging technology.

Hi-tech video goggles with infrared cameras record the eyes’ position and display this on the screen together with the tracings. Clear analyses are provided for slow phase velocity, saccade and tracking data. Interpretation is facilitated by graphic displays comparing results to normative data. The VNG system now features the unique video clips capability for digital video recording and storage