A videonystagmography (VNG) test evaluates the function of the inner ear and the vestibular system, which maintains balance and spatial orientation. This diagnostic procedure measures involuntary eye movements called nystagmus, which can indicate issues within the balance system. While the VNG test is generally not considered painful, it can induce temporary sensations of dizziness, lightheadedness, or nausea. These sensations are expected as the test intentionally stimulates the balance system.
What the VNG Test Involves
The VNG test typically takes about an hour and involves several components to assess the vestibular system. During the procedure, lightweight goggles with infrared cameras record eye movements throughout various tasks. One part, known as oculomotor testing, requires patients to follow moving lights or targets on a screen with their eyes while keeping their head still. This evaluates brain control and coordination of eye movements.
Another section of the test is positional testing, where eye movements are monitored as the head and body are moved into different positions, such as lying down or sitting up. This helps identify abnormal eye movements that might be triggered by changes in position. Caloric testing involves introducing warm and cool air or water into each ear canal, one ear at a time, to assess the responsiveness of the inner ear’s balance organs.
Sensations During the Test
Various sensations are common during the VNG test as the balance system is stimulated. Many individuals report temporary dizziness or a feeling of motion, particularly during the caloric testing portion. This occurs because the warm and cool air or water creates a temperature difference in the ear canal, stimulating the inner ear’s fluid. This temporarily tricks the brain into thinking the head is moving, causing vertigo or spinning.
Some patients might also experience lightheadedness or nausea, especially with the more intense stimulation of the caloric test. These reactions are a normal part of the test designed to provoke responses from the balance system. Technicians closely monitor patients throughout the procedure, and any discomfort is usually temporary, resolving shortly after each test segment. While disorienting, these sensations are not painful and are necessary for accurate diagnostic information.
Preparing for the Test and Aftercare
Proper preparation ensures accurate VNG test results and minimizes discomfort. Patients are typically advised to avoid certain medications for 24 to 48 hours before the test, including anti-dizziness drugs, sedatives, tranquilizers, and some antihistamines, as these can affect the test’s outcome. It is also recommended to avoid alcohol and caffeine for 24 to 48 hours prior to the appointment. Eating a light meal a few hours before the test can help prevent nausea.
Patients should also refrain from wearing eye makeup or facial moisturizers on the test day, as these can interfere with the goggles’ camera tracking. Wear comfortable clothing, as the test involves sitting and lying in various positions. After the test, some individuals might experience lingering dizziness or nausea, though these effects usually subside quickly. Arranging for a ride home is recommended, especially if you anticipate dizziness.
Understanding Your Results
After the VNG test, recorded eye movement data is analyzed by a specialist (e.g., audiologist or ENT doctor). Results provide insights into vestibular system function and can help identify the cause of dizziness or balance problems. Analysis looks for specific patterns of involuntary eye movements (nystagmus), which can indicate issues in the inner ear or the brain’s balance pathways.
The VNG test does not provide a direct diagnosis but offers objective data for a comprehensive evaluation. Abnormal findings may suggest an inner ear balance system disorder or problems with the nerves or brain areas involved in balance. The specialist will discuss findings and may recommend further tests or a treatment plan based on the overall clinical picture.