Do you sometimes feel like you're suddenly dizzy, like everything around you is spinning like a spinning top? Or do you suddenly lose your balance while walking and feel like you're about to fall? There can be many reasons for these things. However, today we are going to talk about a special test that is done to find out if there is a problem with the nerves that control balance in our brain and inner ear. That is the ENG test.
Simply put, what is this ENG test?
The full name of ENG is Electronystagmography. While the name may sound complicated, what it does is very simple. Simply put, ENG is a test that checks the function of some of the important nerves in your brain (cranial nerves) that control eye movement, hearing, and balance .
This test mainly checks to see if your eyes move rapidly back and forth in an uncontrollable manner. In medical terms, we call this condition 'nystagmus' . By analyzing the way your eyes move, this test allows your doctor to get a good idea of the functioning of your inner ear and the parts of your brain that are responsible for balance.
What are those important nerves that are tested with ENG?
Almost every function in our body is controlled by nerves coming from the brain. There are four main nerves that are particularly important for our eyes, ears, and balance that we will focus on in this ENG test. Let's take a look at what they are and what happens to them.
| Nerve Name | What it does (in simple terms) |
|---|---|
| Oculomotor nerve | The eye muscles are connected to the brain and help move the eyes up, down, and inward. |
| Trochlear nerve | A major nerve that helps turn the eyes downward and the nose to the side. |
| Abducens nerve | It helps to turn the eyes sideways, that is, outward from the nose. |
| Vestibular nerve | This is the main nerve that connects our brain from the inside of our ear and controls the body's balance and hearing. |
When is an ENG test needed?
There are two main reasons your doctor might order this test. One is because of the symptoms you're experiencing. The other is to confirm a suspected medical condition.
Do you have symptoms like these?
If you continue to have one or more of the symptoms below, your doctor may suggest an ENG test.
- Balance problems: Feeling unsteady or dizzy when walking, and constantly falling.
- Dizziness and forms of vertigo: This is not just a feeling of spinning. 'Vertigo' is when you feel like the world around you is spinning rapidly, even though you are in one place.
- Unexplained hearing loss: If you have sudden or gradual hearing loss in one ear, this test can help determine if the cause is a problem with the nerves in the inner ear.
ENG also helps diagnose these conditions.
ENG testing provides valuable information during the diagnosis or treatment of certain medical conditions.
- Acoustic neuroma: A noncancerous tumor that develops on the nerve that runs from the ear to the brain.
- BPPV (Benign Paroxysmal Positional Vertigo): A sudden, severe dizziness that occurs when the head is turned in certain directions. Labyrinthitis or vestibular neuritis: Loss of balance due to infection or swelling in the inner ear.
- Ménière's disease: A condition characterized by increased pressure in the inner ear, which causes symptoms such as vertigo, hearing loss, and ringing in the ears.
- Usher syndrome: A genetic condition that affects both hearing and vision.
If you have these symptoms, you should definitely see a doctor and get advice. Don't just assume you have an illness based on information on the internet.
What is the difference between ENG and VNG?
Your doctor may also recommend a VNG (Videonystagmography) instead of an ENG. Although the expected results are the same, there are slight differences in the way it is performed.
- In the ENG test: Eye movement is measured by attaching small metal plates (electrodes) to the skin around your eyes.
- During the VNG test: You will be given a pair of special goggles that use infrared cameras to record your eye movements.
Simply put, although there are slight differences between the two methods, both provide the doctor with the same important information about the functioning of your nerves and inner ear.
How to take the ENG test?
You may feel a little scared when you think about this test. But it's not a painful test. Let's take a look at what happens before, during, and after the test.
How do you prepare before the test?
This usually doesn't require any special preparation. However, it is very important to follow your doctor's instructions.
- Tell your doctor about all the medications you take. You should tell him about everything you take, including vitamins and supplements.
- Your doctor may advise you to temporarily stop taking certain medications, especially sedatives or antivertigo medications, 24 to 48 hours before the test.
What happens during the test?
The ENG test is usually performed by an audiologist. It can take about 90 minutes.
1. Electrode placement: First, several small, sticky metal discs called electrodes are placed above, below, and near the outer corners of your eyes. Another one may be placed on your forehead.
2. Dark room: Then you will be made to sit very comfortably in a chair in a dark room.
3. Testing sessions: This is where the testing begins. They do a few different things to record your eye movements.
- Water or air in the ears: Very carefully, a small amount of warm or cold water (or air) is squirted into your ears from time to time. This stimulates your vestibular nerve, which is responsible for your balance. You may feel a little dizzy during this time, but this is normal and will go away in a few minutes.
- Staring at a light: It tells you to stare at a moving light without moving your head.
- Head movement: You may be asked to do things like quickly get up from a sitting position, or quickly turn your head from side to side.
What happens after the test?
Once the test is over, you can go home normally and resume your normal activities. Any dizziness or nausea you may feel during the test usually goes away completely within the same day.
Is there any risk in this?
This is a very safe, low-risk test. So don't be unnecessarily afraid of it.
Most people do not experience any serious complications. You may experience some minor neck or back pain due to the rapid movements during the test.
Very rarely, there is a small chance that the pressure of putting water in your ear can cause minor damage to your eardrum. However, if you have had a previous perforation of your eardrum, your medical team will be aware of this and will avoid putting water in your ear. So there is no need to worry about it.
What do the test results say?
If your eyes do not move as expected during the test, it may indicate that there is some weakness or damage to the nerves in the brain (cranial nerves). There can be several causes for this type of nerve damage.
- Blood vessel disorders
- A skin growth in the middle ear (Cholesteatoma)
- Certain medications (e.g. some antimalarials, diuretics, or antibiotics)
- Movement disorders
- Multiple sclerosis
- Infections such as rubella
- Traumatic injuries to the head
If your ENG results are abnormal, your doctor may order further tests (such as an MRI scan) to determine the underlying cause. Then, based on that cause, they will decide what treatment you need.
Take-Home Message
- ENG is a painless, safe test that helps determine the cause of your symptoms, such as dizziness and loss of balance.
- This mainly looks at the functioning of the nerves in your brain that control your eyes, ears, and body balance.
- During the test, electrodes are placed around the eyes, water or air is blown into the ears, and eye movements are monitored by moving the head.
- It is very important to inform the doctor about all medications you are taking before the test.
- Whatever the test results, don't be afraid to talk openly with your doctor about it and decide on the next steps to take.
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