Videonystagmography (VNG) Test

Videonystagmography (VNG) testing plays a critical role in the diagnosis of vertigo. This test is particularly used to determine whether symptoms in individuals with dizziness are positional. Patients’ eye movements are examined in detail, ensuring an accurate diagnosis. VNG testing is also a valuable aid when eye movements cannot be fully assessed during an examination. This allows doctors to better understand the causes of symptoms and develop an effective treatment plan.

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What is a Videonystagmography Test?

The videonystagmography test is an effective method for diagnosing vertigo. It is based on the examination of eye movements, particularly focusing on the recording and analysis of nystagmus. Nystagmus is an important indicator for evaluating the functions of the vestibular system, as this system is responsible for the coordination of balance and eye movements. It indicates problems related to the inner ear and brain. With this test, doctors can identify potential disorders in the patient’s balance system.

How Does the Videonystagmography Test Work in Determining Vertigo Symptoms?

The videonystagmography (VNG) test is an effective method used to evaluate vertigo symptoms. This test provides a detailed analysis of the vestibular system and plays a critical role in distinguishing the underlying causes of vertigo. It can detect potential disorders in the inner ear and classify both peripheral and central origin problems.

The VNG test procedure consists of three main sections:

Ocular Test:

Tracking of visual stimuli is performed.
Monitoring eye movements provides information about the functioning of the ocular motor system.
Abnormalities may indicate potential issues in the central vestibular system.

Positional Test:

Patients are moved into different positions to trigger nystagmus.
Conditions like benign paroxysmal positional vertigo (BPPV) are diagnosed with this test.
The type of observed nystagmus indicates whether the source of vertigo is related to the inner ear or the brain.

Caloric Test:

Warm or cold stimuli are applied to the inner ear.
The nystagmus response is recorded and evaluated.
Abnormal responses provide important clues for more specific diagnoses.

What to Expect During a Videonystagmography Test for Vertigo Diagnosis?

During a Videonystagmography test for vertigo diagnosis, the expected procedures are quite detailed. At the beginning of the test, patients are required to avoid certain substances such as alcohol, caffeine, and medications containing sedatives. While the medical history is thoroughly reviewed, the medications you are using will also be examined. A dark test environment ensures that the infrared cameras can more accurately record eye movements.

Test Components:

Ocular Mobility Test: Patients remain in a fixed head position and follow moving and stationary visual targets on the screen. This test measures your eye movement control and response to visual stimuli.
Positional Nystagmus Test: A healthcare professional moves your head and body into various positions. The effects of these movements on your eye movements are observed, and uncontrolled eye movements are detected.
Caloric Test: Warm and cold air or water are applied sequentially to each ear canal. The inner ear’s response to this stimulus helps determine balance disorders.
Rotary Chair Test: You may need to sit on a slowly rotating chair to further stimulate the balance system. The resulting eye movements are recorded during this time.

The test typically lasts about 60 minutes. During the caloric test, you may experience mild discomfort or dizziness; however, these feelings usually dissipate quickly after the test. After completing the test, you may feel dizzy, so it is recommended to have assistance when returning home.

Why is the VNG Test Important in Vertigo Diagnosis?

Videonystagmography (VNG) testing offers a range of advantages in vertigo diagnosis, making it widely preferred. It provides significant benefits in determining the type of the disorder. Central vertigo arises from brain-related issues, while peripheral vertigo typically results from inner ear diseases. VNG can effectively differentiate between these two conditions, allowing for the accurate determination of treatment methods. It clearly shows the differences between the two types.

Videonystagmography evaluates various aspects of the vestibular system with the following tests:

Spontaneous Nystagmus Test: Detects involuntary eye movements.
Gaze Test: Measures the ability of the eyes to focus on a fixed point.
Smooth Pursuit Test: Evaluates the capacity to track moving objects.
Saccade Test: Examines the rapid movements of the eyes between two points.
Optokinetic Test: Tests the ability of the eyes to follow moving objects.
Positional Test and Dix-Hallpike Maneuver: Identifies positional vertigo by observing eye movements while the head is in different positions.

These tests allow VNG to determine whether vestibular loss is unilateral or bilateral. This helps doctors better understand the extent and location of the disorder. Additionally, VNG is a non-invasive method that provides detailed analyses. Using infrared cameras to record eye movements, this technology helps comprehensively analyze underlying causes.

How Does the VNG Test Compare to Other Vertigo Diagnostic Methods?

The videonystagmography (VNG) test is a comprehensive method used in vertigo diagnosis and offers significant advantages compared to other tests. VNG records eye movements using infrared cameras, allowing for clearer and more detailed visualization of eye movements. This makes VNG especially preferred in situations where detailed examination of eye movements is required.

Comparison with Electronystagmography (ENG):

ENG measures corneal-retinal potentials using electrodes.
VNG offers higher resolution and stability, allowing for more accurate detection of eye movements.
ENG may face issues with electrode placement and electrical interference.

VNG is effective in evaluating both peripheral and central vestibular dysfunctions. This broad scope makes VNG valuable, especially in complex vertigo cases. Additionally, the VNG test provides a more comfortable experience for patients as it is a non-invasive method and does not require electrode placement.

Comparison with Caloric Tests:

Caloric testing stimulates the vestibular system by irrigating the ear with water.
VNG records eye movements under various test conditions and evaluates a wide range of vestibular functions.
Caloric tests are particularly effective in assessing unilateral vestibular loss.

When used in conjunction with caloric tests, VNG provides a comprehensive evaluation. This combination allows VNG to offer more information about vertigo and other balance disorders when combined with other tests.

Comparison with Video Head Impulse Test (vHIT):

vHIT measures the vestibulo-ocular reflex and tests the function of the semicircular canals.
VNG includes a series of tests that evaluate both central and peripheral vestibular functions.

How Reliable is the Videonystagmography Test in Diagnosing Different Types of Vertigo?

The videonystagmography (VNG) test is a highly reliable method for diagnosing vertigo. This test plays a critical role in distinguishing various disorders within the vestibular system. VNG excels in detecting both peripheral and central vestibular diseases.

Benign Paroxysmal Positional Vertigo (BPPV): VNG offers particularly high accuracy in determining BPPV. The characteristic nystagmus observed during positional tests clearly indicates the presence of this condition.
Ménière’s Disease: VNG, when combined with other vestibular tests, provides effective results in identifying Ménière’s disease. This combination thoroughly detects disease-specific symptoms and signs.
Central Vestibular Disorders: VNG is an important tool in detecting pathologies in the central vestibular system. It is especially helpful in identifying conditions like cerebellar infarctions.

References:

https://my.clevelandclinic.org/health/diagnostics/22630-videonystagmography

https://medlineplus.gov/lab-tests/videonystagmography-vng/