Videonystagmography (VNG)
Videonystagmography (VNG) is a non-invasive diagnostic test that evaluates the vestibular system, which helps control balance and eye movements. VNG is typically used to diagnose nystagmus, an involuntary eye movement disorder. One of the common causes of nystagmus is an issue with the peripheral vestibular system, which refers to the inner ear’s balance mechanism.
A patient with nystagmus often has unusual eye movements, either from side to side, in circles, or up and down. The movements can be steady, slow, or fast. If the vestibular system is working normally, the brain receives information about which object your eyes should focus on during position changes. Doctors may also recommend a videonystagmography (VNG) when someone has balance problems.
The VNG Testing Procedure
A VNG test is non-invasive, generally well-tolerated, and usually takes about an hour to complete in a clinical setting. A VNG test is usually done by an expert, typically an audiologist, otolaryngologist, or neurologist. You will be asked to sit in a dark room and wear special goggles with a camera to record eye movements. The VNG test typically involves three main parts: oculomotor testing, positional testing, and caloric testing.
Who Needs a VNG?
Videonystagmography (VNG) is used to diagnose balance disorders and ear disorders by analyzing eye movements to help identify the underlying cause of balance-related symptoms. As mentioned, VNG is used for checking vestibular disorders. The test is recommended for patients who may have the following symptoms:
- Vertigo
- Feeling that they are going to fall
- Lightheadedness
- Tinnitus
- Pressure in the ear
- Symptoms of Meniere’s disease, such as episodic vertigo, tinnitus, and hearing loss
Preparation
Patients should avoid caffeine, alcohol, and certain medications prior to the VNG test to ensure accurate results. Your provider will let you know how to prepare for your VNG test. It is also recommended to have a light meal before the test to help reduce the risk of nausea after the procedure. You may need to avoid certain medications and change your diet before the test. Talk to your healthcare provider for details, but don’t stop any medicine immediately.
The Procedure
Oculomotor Testing: This part evaluates the eyes’ ability to follow moving targets and indicates brain-eye coordination. It includes several tests such as the saccade test (measuring the speed and accuracy of rapid eye movements between targets), optokinetic testing (assessing eye movements and gaze stability in response to moving visual stimuli), and the gaze test (evaluating the ability to maintain steady eye position in different gaze directions to detect nystagmus or other abnormalities). These tests involve following a visual target with your eyes without moving the head.
Positional Testing: This includes both the positioning test and positional nystagmus testing. The examiner will move the patient’s head and body into certain positions to provoke or reveal abnormal eye movements such as nystagmus. These maneuvers help assess the vestibulo-ocular reflex and differentiate between central and peripheral vestibular disorders.
Caloric Testing: This is a specific component of VNG that assesses the function of the lateral semicircular canals. The expert may put cool air or water into the ear, which will cause the eye to move in specific ways. Next, they will test the ear again using warm water or air and check eye movements.
Risks
Some patients may feel dizzy after a VNG test. You may want to bring someone with you to help you get home. Minor nausea is common. If you experience any discomfort or pain, let the healthcare provider know.
Test Results
If the VNG test shows abnormalities, your doctor can confirm a condition involving the vestibular system in the inner ear. An abnormal response in VNG test results may include specific eye movement patterns such as increased nystagmus or gaze decay, which can indicate peripheral or central vestibular disorders. The disorder may affect one or both ears. A VNG can help diagnose the following:
- Benign paroxysmal positional vertigo (BPPV): A condition that causes a spinning feeling when the head is moved in specific directions or ways. A positive response during specific tests, such as the presence of nystagmus, can help identify conditions like BPPV.
- Meniere’s Disease: A condition that causes many symptoms, including tinnitus, hearing loss, and vertigo.
- Labyrinthitis: A balance disorder characterized by symptoms such as temporary hearing loss and dizziness.
- Vestibular Neuritis: A condition that affects the vestibular nerve, which conveys information from the vestibular system to the brain. Vestibular neuritis often results from a viral infection and presents with symptoms such as vertigo and nausea.
An abnormal VNG can also indicate conditions that affect the brain parts responsible for controlling balance. There is another test called electronystagmography (ENG), which measures eye movements like a VNG test, but it uses electrodes placed close to the eyes instead of a camera. VNG is often considered more accurate and is faster to complete. An ENG test costs less and can help in some cases.
There are many reasons why your healthcare provider may recommend a VNG. Typically, patients who feel persistently dizzy or have vertigo symptoms need the test. The test doesn’t cause any pain, and in most cases, it takes less than an hour to complete. Additional tests may be necessary for a confirmed diagnosis.
When to Reach Out
If you (or a loved one) are experiencing vertigo symptoms or have unusual eye movements, don’t delay seeking help. A complete and timely diagnosis is critical, and in Westchester and NYC, the Chester Neurology team is your trusted partner throughout the process. We have advanced diagnostic facilities and an expert team of doctors and healthcare providers, providing comprehensive care for all your concerns.
We will guide you through the treatment plan, explain the diagnostic tests, and provide all the details so you always have accurate information about your symptoms and the underlying cause.
Call us today at (914) 816-1941 or email info@chesterneurology.com to schedule an appointment.
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