What is Videonystagmography?
Videonystagmography (VNG) is a diagnostic test used to evaluate and analyze the function of the vestibular (balance) system within the inner ear and the central nervous system. It is commonly employed by healthcare professionals, especially otolaryngologists (ear, nose, and throat specialists) and neurologists, to assess patients with symptoms related to balance disorders, dizziness, and vertigo.
The test involves the use of infrared video cameras to record and analyze eye movements, particularly nystagmus, which is an involuntary rhythmic movement of the eyes. During a VNG test, the patient typically wears infrared goggles equipped with small cameras that track eye movements while the person undergoes a series of positional changes and visual stimuli.
When is a Videonystagmography Test Recommended?
Your physician may recommend a VNG test if you have symptoms of a vestibular disorder, such as:
- Vertigo (a sensation of spinning or whirling) or dizziness
- A history of unexplained falls or balance issues
- Tinnitus or ringing in your ears
- A feeling of pressure or fullness in your ear
- Feeling lightheaded or as if you are going to faint
How Do I Prepare for a Videonystagmography?
The videonystagmography test does not require any special preparation. You may be asked to refrain from certain medications that could affect the results. Hence, it is essential to provide a complete medical history to your healthcare provider.
Other tips to ensure accurate results include:
- Avoid wearing makeup, especially mascara.
- Clean your ears thoroughly.
- Do not wear contact lenses, but you may bring your glasses or contact solution if needed.
- Avoid solid foods for at least 2 hours prior to testing.
- Avoid alcohol or caffeine before the test.
What Happens During a Videonystagmography?
In general, a VNG test may involve the following key components:
- Introduction of Equipment: The patient is fitted with infrared goggles that are equipped with small cameras to track eye movements. The goggles are connected to a computer system that records and analyzes the data.
- Spontaneous Nystagmus: The initial part of the test assesses spontaneous nystagmus, which means observing the patient's eye movements without any specific stimulation. The patient may be instructed to focus on a stationary target while sitting still.
- Gaze Testing: The patient is asked to follow visual targets with their eyes as they move in different directions. This helps assess the function of the vestibular system in response to changes in gaze direction.
- Positional Testing: The patient undergoes a series of head and body position changes to provoke nystagmus. This may include sitting up, lying down, turning the head, and moving into specific positions.
- Caloric Testing: Warm and cold air or water is introduced into each ear separately to stimulate the inner ear. This assesses the vestibular response and helps identify any asymmetry between the two ears.
- Optokinetic Testing: The patient may be exposed to moving visual stimuli, such as a rotating drum or moving stripes, to evaluate eye movements in response to visual motion.
Throughout the test, the healthcare provider observes and analyzes the eye movements recorded by the infrared cameras. The information obtained from VNG testing helps in diagnosing vestibular disorders, identifying the underlying causes of balance issues, and developing appropriate treatment plans.
What Happens After Videonystagmography?
A VNG study typically takes around 1 hour. You may feel slightly dizzy during and immediately after the study. Generally, dizziness goes away quickly. If it persists, you will need someone to drive you home.
Interpretation of a Videonystagmography Test
If your VNG test results are deemed abnormal, it may indicate you have a disorder of the vestibular system. A VNG test can help diagnose several vestibular disorders, such as:
- Vestibular neuritis: A condition that affects the vestibular nerve, which connects the inner ear to the brain, causing prolonged vertigo usually in the absence of significant hearing loss.
- Meniere's disease: This disorder causes vertigo, hearing loss, tinnitus, and a full feeling in your ears. It happens when too much fluid builds up in the inner ear.
- Labyrinthitis: This balance disorder occurs when sections of your inner ear become irritated and inflamed (swollen), usually from a cold or flu.
- Acoustic neuroma: This is a noncancerous tumor that develops on the nerves involved with hearing and balance and can cause hearing loss or dizziness.
- Benign paroxysmal positional vertigo (BPPV): A condition characterized by brief episodes of vertigo triggered by specific head movements.