The purpose of the Vestibular Function Tests ( VFTs ) is to determine the health status of the vestibular portion of the inner ear. VFTs are used to determine if your dizziness, vertigo, or balance problem is caused by a brain disorder. These tests are commonly managed by specialists in ear, nose and throat, audiologists and otolaryngologists.
Electronystagmography or Videonystagmography
An electronystagmography ( commonly called an ENG test ) or VNG ( VNG test ) tests the inner ear. Both record eye movements during a test group in a dark room and lit one.
During the test, small electrodes are placed on the skin near the eyes to record eye movements. For proof of VNG, eye movements are recorded by a video camera mounted in a pair of glasses that are used during the test.
Electronystagmography VNG test and evaluate eye movement during different activities such as following a visual target ( screening test ); during rapid eye movement ( calibration test ); for changes in head position ( positional test ); or in response to hot or cold air or water placed in the ear canal ( caloric test ). If no response to hot or cold air or water, we can use ice water to induce a response. The caloric test helps determine if there is a difference between the left and right inner ear. A patient will be asked questions ( math, city names, alphabet ) to distract him from concentrating on his response to the test. A routine hearing test ( audiogram ) is an important part of the examination of a patient with dizziness and is frequently completed before the ENG or VNG.
Rotational (Swivel) Chair Test
The test of the swivel chair is used to help determine if symptoms are due to a disorder of the inner ear or brain disorder. Eye movements are recorded with small electrodes similar to those used during the ENG test. Not all individuals need swivel chair test to help with diagnosis. Many health institutions do not have access to a computerized swivel chair. The test of the swivel chair allows measures in response to head movements are closer to speeds encountered in daily activities. During this test, a patient sits in a computerized chair that moves. The swivel chair test is useful in determining whether an individual has a problem with both sides of the vestibular system ( bilateral vestibular loss ).
Computerized Dynamic Visual Acuity (DVA)
Computerized DVA testing helps determine how your vestibular problem affects your vision during activities such as walking, riding in a car on bumpy roads, or turning your head from side to side. This is a useful tool to help measure changes in the vestibular ocular reflex ( VOR ) after vestibular rehabilitation and to determine if your brain has compensated for a vestibular test problem. The VOR allows objects to be concentrated while the head is moving. Individuals who have problems with the VOR may have oscillopsia, or rebound, unstable vision and are unable to keep objects in focus during head movement.
Subjective Visual Vertical
Subjective Visual Vertical test ( SVV ) evaluates the utricle, which is one of the inner ear organs responsible for sensing gravity. During the SVV test, you will be in a dark room and are asked when an image of a line projected is in a vertical or horizontal position. Typically, you will perform this test 10 times. It has been found that this test is useful for patients with vestibular neuritis, lesions in the inner ear, or nerve injuries, transmitting information from the inner ear to the brain.
Vestibular Evoked Myogenic Potential (VEMP)
The purpose of this test is to determine whether the saccule ( one of the bodies internal ) ear and the vestibular nerve are working normally. Saccule is sensitive to sound and this response can be measured by recording electrical activity in a muscle located in the front of the neck muscle ( sternocleidomastoid ). Small electrodes are applied to the neck, loud and repetitive popping sounds are sent to each ear. The response is recorded as electrical muscle. Because this test is based on sound, hearing must be intact for the test to be completed.