Vertigo, dizziness, and balance problems can be life altering. For many people it can affect their ability to do even the simplest daily tasks. If you are experiencing vertigo or balance issues, your doctor may want to refer you for a videonystagmography (VNG) or other balance evaluation.
What is a VNG balance evaluation?
A VNG is a series of tests that evaluate the health of your vestibular (balance portion of inner ear) and your central motor function. VNG testing can help to uncover the root cause of your vertigo, dizziness or balance issues, and allows your doctor or hearing specialist to treat it appropriately and effectively.
What tests will be performed?
VNG testing consists of a variety of tests to uncover the root cause of your symptoms. Most VNG evaluations consist of four main tests:
Ocular mobility
This test checks for your ability to follow visual targets, such as a moving light on a bar. You will attempt to follow targets with your eyes while an object is jumping, moving slowly, or standing still. Inability to track objects properly could indicate central or neurological problems or possibly an issue with the vestibular system connecting to the brain. Recording and evaluating eye movements is helpful because visual motor neural pathways are connected to the vestibular or balance system of the inner ear.
Optokinetic nystagmus
This test also checks for your ability to follow visual targets. During this test, you will watch a image that is continuously moving and will be asked to follow the movements. Similarly, this test will give clues to possible central or neurological problems or problems with the vestibular system.
Positional nystagmus
This test will help give an idea of the health of your inner ear system. You will be asked to move your head and body into different positions, allowing the hearing care professional to check for inappropriate eye movements in each position.
Caloric testing
This test can help determine if you have vestibular weakness in one or both ears by checking to see if your vestibular system responds properly to stimulus. Your eyes will be monitored while your inner ears are stimulated (one at a time) with warm or cold air or water.
Preparing for VNG testing
Because of the nature of the tests, there are some preparations you will need to make before your evaluation. Our staff will provide you with clear instructions on how to prepare for your examination. For example, we may ask you to discontinue certain medications, not to consume any alcoholic beverages or caffeinated drinks at least 48 hours before the tests, to remove contact lenses or eyeglasses or to fast for a few hours prior to testing. The exact instructions may vary from patient to patient. If you have any questions about your instructions or how to prepare for the test, ask your hearing health professional.
The entire VNG evaluation typically lasts about 90 minutes and can cause some dizziness. This dizziness usually subsides within a short period of time. It is advised that you bring someone with you who can drive you home afterward if you are unable to drive or do not feel well after the tests.
Video Head Impulse Test (VHIT)
This test allows for the evaluation of the vestibular system by examining all 6 semicircular canals and is now considered the most important initial test of vertigo. The test involves wearing lightweight goggles while the examiner moves your head from side to side and takes about 20-30 minutes to administer with minimal discomfort to the patient.
Auditory Brainstem Evoked Response Test (ABR)
This test assesses the electrical nerve impulses and how well they carry sound from the inner ear to the brain. It involves placing electrodes on the forehead and behind the ears. This is a non-invasive test that requires the patient to simply lie down and relax or sleep while listening to clicks.