VNG Balance Evaluations
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) 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:
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.
This test also checks for your ability to follow visual targets. During this test, you will watch an 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.
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.
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
Our staff will provide you with clear instructions on how to prepare for your examination. 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.
Balance and Equilibrium Service
Audiology tests can provide information about hearing, middle ear function, cochlear hair cell function and several neural aspects of the hearing-balance system. Although there are many ear related conditions, which cause hearing loss along with vertigo, there are many that do not. So, the presence of an accompanying hearing loss with the vertigo symptoms may help differentiate certain ear disease-disorders from one another.
Audiology testing often includes: Pure tone (air and bone) and word discrimination tests as well as Immittance Audiometry which evaluates middle and inner ear and some neurological pathways. Otoacoustic Emissions is a relatively new test that looks at the outer hair cell function within the inner ear (cochlea). Brainstem Auditory Evoked Response (BAER) tests the neural conductivity of the hearing and balance nerve (CN VIII).
Gans Sensory Organization Performance Test:
A combination of the Romberg, clinical test of sensory integration of balance (CTSIB) and Fukuda Stepping Tests provide qualitative information on whether an equilibrium dysfunction exists, whether it is CNS or peripheral and also serves as an indicator of impact on balance function. Whether the is patient surface or visually dependent gives insight into the status of the vestibular system. Recovery of function post treatment may also be documented.
Computerized Dynamic Visual Acuity Test (CDVAT)
This tests for a change in vision with controlled head movement. Oscillopsia is a breakdown in gaze stabilization during active head movement caused by peripheral or central vestibular disorders. The vision test is conducted while the patient produces horizontal and then vertical head movement of 2.5 cycles per second. The test indicates the function problem caused by the vestibular dysfunction and can be used as a baseline to latter compare improvement post Vestibular Rehabilitation Therapy (VRT) to document the treatment efficacy.
Vestibular Autorotation Testing
VOR function gain and phase is quantitatively analyzed using this active rotation test for both horizontal and vertical head movements over a frequency range of approximately 2-8 cycles per second. The patient is required only to look straight ahead while moving their head to an auditory cuing signal. This test provides diagnostic as well as outcome measurements. This test can be obtained through passive tests like the Rotary Chair, in which the patient simply sits while being harmonically accelerated, or active tests, in which the person volitionally moves their head to an auditory cue.
Vestibular-Evoked Myogenic Potentials (VEMPs)
Vestibular-evoked myogenic potential testing (VEMPs) is based on the reflex, which occurs between the otolith system (specifically the saccule), and the sternocleidomastoid muscle (SCM). The vestibulo-collic reflex (VCR) has been well studied in animals and humans. The benefit of VEMPs is there is no other vestibular function test, which provides information regarding the saccule or its innervation by the inferior branch of the vestibular nerve. As the VCR is a classic reflex arc with a sensory, CNS, and motor output component, it has been used to provide information regarding both the integrity of the saccule and inferior vestibular nerve, as well as the reflex arc through the brainstem. This has provided information on both otologic and neurologic conditions.
Call Audiology Center of Maine at (207) 430-3714 for more information or to schedule an appointment.