Difference Between VEMP and VNG Test for Vertigo Diagnosis

Vertigo, the unsettling sensation of spinning or unsteadiness, is not a standalone illness but rather a symptom indicating an underlying issue within the complex balance system. Accurately diagnosing the root cause of vertigo is paramount for effective treatment. This often requires specialised diagnostic tests that can objectively assess how different parts of the balance system are functioning. 

The most often used devices are Videonystagmography (VNG) and Vestibular Evoked Myogenic Potentials (VEMP). Both measures are essential in understanding vertigo, but each one examines different parts of the balance control system, and based on your condition, the doctor might suggest one or both.

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What is Videonystagmography (VNG)?

VNG is a test that monitors eye movements as people respond to different stimuli like moving objects, change of body and head position or increase or decrease in the temperature of the tympanic membrane in the ear.

• Purpose: VNG mainly assesses how well the VOR (Vestibulo-ocular-reflex) functions, a process that links the organs of balance in the inner ear to eye movement-controlling muscles. The test monitors eyes (nystagmus) and uses them to see how balance information travels from the inner ear, through nerves, to the brain.
  
• How it works: When you take a VNG test, you’ll wear a pair of goggles equipped with high-speed infrared cameras that closely monitor your eye movements. The test involves a series of tasks, such as following moving objects, focusing on stationary targets, and changing your head and body positions. In most cases, the VNG also includes caloric testing, where warm or cool air (or water) is gently introduced into the ear canal to stimulate the balance organs in the inner ear and observe their response.

• Clinical application: VNG is particularly useful in:
  • Diagnosing Benign Paroxysmal Positional Vertigo (BPPV), one of the most common causes of vertigo. The positional testing within VNG can trigger the specific type of nystagmus characteristic of BPPV and help determine the location of the dislodged crystals in the inner ear canals.
  • Helping to differentiate between central balance disorders (problems in the brain) and peripheral balance disorders (problems in the inner ear or vestibular nerve).
  • Evaluating conditions like vestibular neuritis or labyrinthitis.

What is Vestibular Evoked Myogenic Potentials (VEMP)?

Vestibular Evoked Myogenic Potentials (VEMP) is a test that measures muscle responses to sound stimulation of the inner ear’s balance organs, specifically the otolith organs (the saccule and utricle).

• Purpose: Unlike VNG which focuses on the semicircular canals and their connection to eye movements, VEMP directly assesses the function of the saccule (sensitive to vertical movement) and the utricle (sensitive to horizontal movement), and their neural pathways connecting to specific neck and eye muscles.
  
• How it works: Small electrodes are placed on your neck (cervical VEMP or cVEMP) or under your eyes (ocular VEMP or oVEMP). You will then listen to sounds (usually clicks or tones) delivered through headphones. These sounds stimulate the saccule (for cVEMP) or the utricle (for oVEMP). The electrodes record the tiny, involuntary muscle responses that occur as a result of this stimulation.
  
• Clinical application: VEMP is valuable in:
  • Detecting dysfunction in the otolith organs and their pathways.
  • Assessing conditions like Superior Canal Dehiscence Syndrome (SCDS), where there is an abnormal opening in one of the inner ear canals, making the inner ear unusually sensitive to sound.
  • Providing information relevant to diagnosing Meniere’s Disease, which affects fluid balance in the inner ear.

Key Differences Between VEMP and VNG

While both are vestibular tests, they assess distinct components of the balance system and use different methodologies:

Why Both Tests May Be Recommended

Doctors often recommend both VNG and VEMP tests together to ensure a comprehensive and accurate diagnosis of vertigo. Since many balance disorders can affect different components of the vestibular system, combining these tests helps identify issues that might be missed if only one test is performed. This approach allows doctors to better distinguish between peripheral and central causes of vertigo and create a more targeted and effective treatment plan.

The Role of Specialists and Advanced Clinics

Tests like VNG and VEMP can be tricky to understand, so you need doctors who are specially trained to figure out what the results mean. These are usually experts like neurotologists, ENT doctors, or neurologists—they are the best people to look into your vertigo since it is their specialised domain and they will have ample experience with the same. They can interpret your VNG or VEMP reports and correlate it with your medical history to find out the specific cause of vertigo.

Advanced clinics, like NeuroEquilibrium, use these tests and other tools to understand what’s causing your dizziness or vertigo. With the right equipment and expert knowledge,we can find out exactly what’s wrong and create a treatment plan just for you. Book an appointment today.

Conclusion

Doctors often use both these tests together because each one checks something different. When they put all the information together, they can figure out the real cause of your vertigo.

If your dizziness doesn’t go away and is making life hard, it’s a good idea to see a vertigo specialist or visit a clinic like NeuroEquilibrium.Book an appointment today.

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