Angelica Bottaro is a writer with expertise in many facets of health including chronic disease, Lyme disease, nutrition as medicine, and supplementation.
Johnstone M. Kim, MD, is a board-certified ophthalmologist and a practicing physician at Midwest Retina in Dublin, Ohio.
Electronystagmography (ENG) is a type of test that examines the function of brain nerves through visual movements of the eyes. It looks at specific nerves in the brain such as the vestibular nerve , oculomotor nerve , and trochlear and abducens nerves . It is commonly used to diagnose vertigo or other conditions that cause issues with balance.
This article reviews the electronystagmography procedure and why it's used.
People who experience any type of vestibular dysfunction , which involves the inner ear and parts of the brain, will typically have to undergo electronystagmography. Vestibular dysfunction occurs when there are issues within the sensory system that cause balance or coordination issues.
This test is considered the gold standard when it comes to diagnosing conditions such as vertigo.
The test also is used to examine or diagnose a variety of other health conditions associated with damage to the specific brain nerves, such as:
Any condition that causes dizziness or imbalance may be investigated using an ENG because those symptoms can indicate damage has occurred to one or more of the nerves that play a role in balance and movement.
Videonystagmography (VNG) is a test that is similar to ENG in that it's used to determine if there are any issues within the vestibular system. However, a VNG uses different tools to get a similar read on how the system is functioning.
While there are very few risks associated with the procedure, in some cases, an eardrum can rupture. This is because a portion of the test involves spraying water or air into the ear. If there is too much pressure because of the water within the ear, it can cause injury (in rare instances).
Those with pacemakers should not get an ENG test because the pacemaker can interfere with the results of the test.
You will likely not have to make any special arrangements prior to your test. However, there are some things you should know before arriving.
The procedure itself will take roughly 90 minutes. Since waiting room times vary depending on location and appointment time, you should try to allot at least two hours out of your day for the exam.
An ENG usually is performed in a hospital. It may be performed on an outpatient basis in a single day, after which you are able to go home. Or you may wait in the hospital to discuss a diagnosis with your healthcare provider.
While you will not be required to wear any special clothing, you may want to wear something comfortable for the exam.
Since water will be sprayed into your ear for the test, your clothes may get wet, so you may want to bring a change of clothing for afterward.
You will also be asked to remove earrings and other jewelry prior to the test, so you may want to avoid wearing them to your appointment.
It's recommended that you avoid eating or drinking in the morning prior to the test. Avoiding food is helpful because the test may cause nausea in some people, and having food in your stomach could lead to vomiting if the nausea is particularly severe.
You should also avoid alcohol and tobacco products prior to the test.
You should take your regular medications as prescribed by your healthcare provider. Your provider will tell you if any of the medications you are taking will interfere with the test and should be stopped prior to the test.
Most medical insurance providers will cover either a portion of or all of the costs associated with an ENG. That being said, if it is not covered for some reason or if you do not have insurance, the test itself can cost anywhere between $150 and $500.
The only things you may need to bring with you on the day of your test are a form of identification, your insurance card, and another person to drive you home. Although the procedure isn’t invasive, it can be highly stimulating and cause side effects, so it’s best to have a person chaperone you on the day of the examination.
It's suggested that you avoid the use of any cosmetic products on the day of your test. This includes makeup as well as perfume. You will be asked to remove both if you choose to wear them to your test.
When you arrive for your test, you will have to fill out paperwork regarding your medical history and insurance. You will also have to sign a consent form that states you understand the procedure and are consenting to have it done. You will then be brought into the test room to set up.
Before the test begins, any earwax you may have will be removed from your ear. Areas of your face will be cleaned and prepped for the electrodes, which are medical devices designed to transfer energy into the body.
Once the area is prepped, the electrodes will be secured onto the skin using a paste with one on the center of your forehead and others above and below the eyes.
Once the test has begun, cold water or air will be sprayed into one ear canal at a time to stimulate the nerves being tested. At that time, eye movements will be recorded to assess how the nerves are stimulated by the cold air or water. Typically, the eye movements are rapid and side to side.
Warm water or air will be used following the cold to record your eye movements. In contrast to the cold water or air eye movements, the warm water should elicit a different response that involves a rapid movement of the eyes toward the warm water or air and then a slow movement away from the ear.
You may be asked to move your head or entire body to one side or looking up, down, or to the side.
In some cases, the eyes can remain closed. However, you may also be asked to track flashing lights or moving lines while the test is underway.
Once the test is complete, the electrodes will be removed and the area will be cleaned. You will not be able to exit the exam room immediately because the test can cause you to experience uncomfortable side effects, such as nausea.
After the test is finished, the healthcare provider will examine you for any side effects such as nausea, dizziness, or weakness.
Since the test may come with some side effects, you may be asked to lie down for a few minutes before exiting the exam room. This is to ensure that you do not fall from a lack of balance or experience any vomiting as a result of the nausea.
If the test comes back normal, then your healthcare provider will have to determine what is causing your symptoms through different methods. Abnormal test results typically mean that there is damage to either the nerves that control eye movements or your inner ear.
As previously mentioned, this test typically is used to diagnose a person who is experiencing symptoms of vertigo. However, it can be used in the diagnostic process of various other health conditions.
Other possible reasons a person may experience abnormal results include:
The normal results of these types of tests can vary, so it’s important to speak to your healthcare provider about your specific results and what they mean for you and your health.
The follow-up appointment following an ENG is used to discuss results with your healthcare provider. They will examine the results and determine what they suspect is the cause of your symptoms.
Once they have done that, they can either provide you with a possible treatment plan or order more tests in the event that they suspect something more serious than vertigo is at play.
An electronystagmography typically is used to diagnose vertigo, but it can also be a tool in diagnosing other health conditions that lead to dizziness and issues with balance. The test involves placing electrodes above and below the eyes as well as the forehead so that healthcare providers can watch whether your eye movements are in the normal range when stimulated with air or water in the ears.
Healthcare providers will review the results of the test and determine if vertigo or another condition is the cause of symptoms.
While getting an ENG can be uncomfortable, it's an important diagnostic tool that is used to help address unwanted symptoms of dizziness or a lack of balance. The test is used to diagnose vertigo, which, fortunately, can be treated effectively. When your healthcare provider orders the test, be sure to ask them any questions and follow their instructions so that you can get the most accurate results and diagnosis.
While the test itself isn’t likely to cause any pain, it can be uncomfortable for some people. This is because when water or air is sprayed into the ear canal, it can create a sense of pressure. Nausea is a common side effect of the test.
Generally speaking, you can go home and resume your daily activities following your ENG. That said, you may feel unwell following the test so you should plan to spend the rest of the day relaxing. In some cases, you may have the test during a hospital stay and, in this case, you will return to your hospital room following the examination.
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Gupta SK, Mundra RK. Electronystagmography a very useful diagnostic tool in cases of vertigo. Indian J Otolaryngol Head Neck Surg. 2015;67(4):370-374. doi:10.1007/s12070-015-0859-y
University of Rochester Medical Center. Electronystagmography (ENG).
Johns Hopkins Medicine. Electronystagmography (ENG).
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