- Electroencephalogram (EEG)
- Sleep EEG or sleep-deprived EEG
- Ambulatory EEG
- Video telemetry
- Understanding Your EEG Results | Normal & Abnormal EEGs
- What are the risks of an EEG?
- How do I get ready for an EEG?
- What happens during an EEG?
- What happens after an EEG?
- Next steps
- How to Prepare
- How It Is Done
- How It Feels
- Electroencephalography (EEG)
- What happens during an EEG test?
- How should I prepare for an EEG?
- Locations/Contact Information
- EEG Electroencephalogram
- How does an EEG work?
- What does an EEG show?
- Who performs the test?
- How should I prepare for the test?
- What happens during the test?
- What happens after the test?
- How do I get the test results?
- Sources & links
- EEG (Electroencephalogram)
- Why It's Done
- The Procedure
- What to Expect
- Getting the Results
- Helping Your Child
- If You Have Questions
- EEG – Electroencephalogram
- Who does an EEG?
- Why do an EEG?
- How can technicians get the most information from an EEG?
- Where do you go for an EEG?
- How do I prepare my child for the EEG?
- Sleep-deprived EEG
- What happens at the hospital before the EEG?
- You can go with your child into the recording room
- Tell the technician about any skin allergies
- The technician will attach about 24 small silver discs to your child's head
- It is important for your child to lie still
- Your child needs to open and close their eyes and breathe in and out deeply
- Your child will then have a short sleep
- What happens after the EEG recording?
- How long do the EEG results take?
An electroencephalogram (EEG) is a recording of brain activity.
During the test, small sensors are attached to the scalp to pick up the electrical signals produced when brain cells send messages to each other.
These signals are recorded by a machine and are looked at by a doctor later to see if they're unusual.
The EEG procedure is usually carried out by a highly trained specialist, called a clinical neurophysiologist, during a short visit to hospital.
An EEG can be used to help diagnose and monitor a number of conditions affecting the brain.
It may help identify the cause of certain symptoms – such as seizures (fits) or memory problems – or find out more about a condition you've already been diagnosed with.
The main use of an EEG is to detect and investigate epilepsy, a condition that causes repeated seizures. An EEG will help your doctor identify the type of epilepsy you have, what may be triggering your seizures and how best to treat you.
Less often, an EEG may be used to investigate other problems, such as dementia, head injuries, brain tumours, encephalitis (brain inflammation) and sleep disorders, such as obstructive sleep apnoea.
Your appointment letter will mention anything you need to do to prepare for the test.
Unless told otherwise, you can usually eat and drink beforehand and continue to take all your normal medication.
To help the sensors stick to your scalp more easily, you should make sure your hair is clean and dry before arriving for your appointment, and avoid using products such as hair gel and wax.
You might want to bring a hairbrush or comb with you, as your hair may be a bit messy when the test is finished. Some people bring a hat to cover their hair until they can wash it at home afterwards.
There are several different ways an EEG recording can be taken. The clinical neurophysiologist will explain the procedure to you and can answer any questions you have.
You'll also be asked whether you give permission (consent) for the various parts of the test to be carried out.
Before the test starts, your scalp will be cleaned and about 20 small sensors called electrodes will be attached using a special glue or paste. These are connected by wires to an EEG recording machine.
Routine EEG recordings usually take 20 to 40 minutes, although a typical appointment will last about an hour, including some preparation time at the beginning and some time at the end.
Other types of EEG recording may take longer.
A routine EEG recording lasts for about 20 to 40 minutes.
During the test, you'll be asked to rest quietly and open or close your eyes from time to time. In most cases, you'll also be asked to breathe in and out deeply (called hyperventilation) for a few minutes.
At the end of the procedure, a flashing light may be placed nearby to see if this affects your brain activity.
Sleep EEG or sleep-deprived EEG
A sleep EEG is carried out while you're asleep. It may be used if a routine EEG does not give enough information, or to test for sleep disorders.
In some cases, you may be asked to stay awake the night before the test to help ensure you can sleep while it's carried out. This is called a sleep-deprived EEG.
An ambulatory EEG is where brain activity is recorded throughout the day and night over a period of one or more days. The electrodes will be attached to a small portable EEG recorder that can be clipped onto your clothing.
You can continue with most of your normal daily activities while the recording is being taken, although you'll need to avoid getting the equipment wet.
Video telemetry, also called video EEG, is a special type of EEG where you're filmed while an EEG recording is taken. This can help provide more information about your brain activity.
The test is usually carried out over a few days while staying in a purpose-built hospital suite.
The EEG signals are transmitted wirelessly to a computer. The video is also recorded by the computer and kept under regular surveillance by trained staff.
When the test is finished, the electrodes will be removed and your scalp will be cleaned. Your hair will probably still be a bit sticky and messy afterwards, so you may want to wash it when you get home.
You can usually go home soon after the test is finished and return to your normal activities. You might feel tired after the test, particularly if you had a sleep or sleep-deprived EEG, so you may want someone to pick you up from hospital.
You normally will not get your results on the same day. The recordings will need to be analysed first and will be sent to the doctor who requested the test. They can discuss the results with you a few days or weeks later.
The EEG procedure is painless, comfortable and generally very safe. No electricity is put into your body while it's carried out. Apart from having messy hair and possibly feeling a bit tired, you normally will not experience any side effects.
However, you may feel lightheaded and notice a tingling in your lips and fingers for a few minutes during the hyperventilation part of the test. Some people develop a mild rash where the electrodes were attached.
If you have epilepsy, there's a very small risk you could have a seizure while the test is carried out, but you'll be closely monitored and help will be on hand in case this happens.
Understanding Your EEG Results | Normal & Abnormal EEGs
Your doctor may recommend an EEG (electroencephalogram) to diagnose the cause of symptoms, such as seizures or memory loss. An EEG evaluates brain function by measuring the electrical activity within the brain. It records patterns of activity during rest and in response to certain stimuli. This helps your doctor diagnose and evaluate brain disorders and conditions.
Keep in mind that electroencephalography is only one part of a comprehensive diagnostic workup. A doctor who specializes in neurology or neurosurgery will interpret your EEG results in the context of other tests and clinical information.
The test can only reveal what is happening in the brain; it can’t explain why it’s happening. That requires the expertise of your doctor.
When discussing your test results with your doctor, it's helpful to have background information on the test itself and normal and abnormal EEG results.
Electrical activity in the brain is recorded as a ‘wave.’ There are many types of brain waves that an EEG records. The basic brain waves are alpha, beta, theta, and delta waves. There are other more complex waves.
Each type of brain wave has a normal frequency, height, shape, and location. A person’s age can also determine whether a certain brain wave is normal or not. For example, delta waves are normal in young children. They are not normal for adults who are awake.
Your doctor examines each facet of a wave to determine if it is normal or not.
Abnormal EEG results can show up in two ways. First, normal brain activity may be suddenly interrupted and changed. This happens in epileptic seizures. In partial seizures, only part of the brain shows the sudden interruption. The whole brain shows it in generalized seizures.
The other way an EEG can show abnormal results is called non-epileptiform changes. This can be a general change in the way a normal brain wave looks.
It may have an abnormal frequency, height or shape. It can also be a brain wave showing up that should not. For example, a delta wave occurring in an adult who is awake is not normal.
This wave typically occurs in adults when they are in deep sleep.
Doctors use information from an EEG to gain insight into brain activity.
1. Alpha waves are related to relaxation and attention. They are present when you are awake with your eyes closed. They usually disappear when you open your eyes and pay attention to something.
2. Beta waves are normal in people who are awake. It doesn’t matter whether your eyes are open or closed. Certain drugs, such as sedatives, can influence these waves.
3. Theta waves are related to sleep. These slow waves are normal for all ages during sleep. They generally aren’t obvious when adults are awake.
4. Delta waves are also related to sleep. These waves are normal in adults who are in deep sleep and in young children.
Other brain waves and EEG patterns give doctors information about sleep stages, how easily you can be roused from sleep, and problems with the structure of the brain.
An abnormal EEG means that there is a problem in an area of brain activity. This can offer a clue in diagnosing various neurological conditions. Read 10 Conditions Diagnosed With an EEG to learn more.
EEG testing is one part of making a diagnosis. The results may not pinpoint a specific diagnosis, but it can narrow the possibilities.
Second opinions can be a valuable tool when trying to establish a neurological diagnosis. Remember that a second opinion on your test results is not a negative reflection on your doctor. It offers additional input and reassurance about your situation.
What are the risks of an EEG?
The EEG has been used for many years and is considered a safe procedure. The test causes no discomfort. The electrodes record activity. They do not produce any sensation. In addition, there is no risk of getting an electric shock.
In rare instances, an EEG can cause seizures in a person with a seizure disorder. This is due to the flashing lights or the deep breathing that may be involved during the test. If you do get a seizure, your healthcare provider will treat it immediately.
Other risks may be present, depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider before the procedure.
Certain factors or conditions may interfere with the reading of an EEG test. These include:
- Low blood sugar (hypoglycemia) caused by fasting
- Body or eye movement during the tests (but this will rarely, if ever, significantly interfere with the interpretation of the test)
- Lights, especially bright or flashing ones
- Certain medicines, such as sedatives
- Drinks containing caffeine, such as coffee, cola, and tea (while these drinks can occasionally alter the EEG results, this almost never interferes significantly with the interpretation of the test)
- Oily hair or the presence of hair spray
How do I get ready for an EEG?
Ask your healthcare provider to tell you what you should do before your test. Below is a list of common steps that you may be asked to do.
- Your healthcare provider will explain the procedure to you and you can ask questions.
- You will be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
- Wash your hair with shampoo, but do not use a conditioner the night before the test. Do not use any hair care products, such as hairspray or gels.
- Tell your healthcare provider of all medicines (prescription and over-the-counter) and herbal supplements that you are taking.
- Discontinue using medicines that may interfere with the test if your healthcare provider has directed you to do so. Do not stop using medicines without first consulting your healthcare provider.
- Avoid consuming any food or drinks containing caffeine for 8 to 12 hours before the test.
- Follow any directions your healthcare provider gives you about reducing your sleep the night before the test. Some EEG tests require that you sleep through the procedure, and some do not. If the EEG is to be done during sleep, adults may not be allowed to sleep more than 4 or 5 hours the night before the test. Children may not be allowed to sleep for more than 5 to 7 hours the night before.
- Avoid fasting the night before or the day of the procedure. Low blood sugar may influence the results.
- your medical condition, your healthcare provider may request other specific preparations.
What happens during an EEG?
An EEG may be done on an outpatient basis, or as part of your stay in a hospital. Procedures may vary depending on your condition and your healthcare provider's practices. Talk with your healthcare provider about what you will experience during your test.
Generally, an EEG procedure follows this process:
- You will be asked to relax in a reclining chair or lie on a bed.
- Between 16 and 25 electrodes will be attached to your scalp with a special paste, or a cap containing the electrodes will be used.
- You will be asked to close your eyes, relax, and be still.
- Once the recording begins, you will need to remain still throughout the test. Your healthcare provider may monitor you through a window in an adjoining room to observe any movements that can cause an inaccurate reading, such as swallowing or blinking. The recording may be stopped periodically to let you rest or reposition yourself.
- After your healthcare provider does the initial recording while you are at rest, he or she may test you with various stimuli to produce brain wave activity that does not show up while you are resting. For example, you may be asked to breathe deeply and rapidly for 3 minutes, or you may be exposed to a bright flashing light.
- This study is generally done by an EEG technician and may take approximately 45 minutes to 2 hours.
- If you are being evaluated for a sleep disorder, the EEG may be done while you are asleep.
- If you need to be monitored for a longer period of time, you may also be admitted to the hospital for prolonged EEG (24-hour EEG) monitoring.
- In cases where prolonged inpatient monitoring is not possible, your doctor may consider doing an ambulatory EEG.
What happens after an EEG?
Once the test is completed, the electrodes will be removed and the electrode paste will be washed off with warm water, acetone, or witch hazel. In some cases, you may need to wash your hair again at home.
If you took any sedatives for the test, you may be required to rest until the sedatives have worn off. You will need to have someone drive you home.
Skin irritation or redness may be present at the locations where the electrodes were placed, but this will wear off in a few hours.
Your healthcare provider will inform you when you may resume any medicines you stopped taking before the test.
Your healthcare provider may give you additional or alternate instructions after the procedure, depending on your particular situation.
Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure
How to Prepare
Before the day of the electroencephalogram (EEG) test, your doctor will need to know what medications you are taking.
Avoid foods that contain caffeine (such as coffee, tea, cola, and chocolate) for at least 8 hours before the test. Eat a small meal shortly before the test, because low blood sugar (hypoglycemia) may produce an abnormal test.
Since the electrodes are attached to your scalp, it is important that your hair be clean and free of sprays, oils, creams, lotions, and other hair preparations. Shampoo your hair and rinse with clear water the evening before or the morning of the test. Do not apply any hair conditioners or oils after shampooing.
To detect certain types of abnormal electrical activity in the brain, you may have to be asleep during the recording. As a result, you may be asked to reduce your sleep time to 2 to 3 hours the night before the test by going to bed later and getting up earlier than usual. If you know that you are going to have a sleep-deprived EEG, plan to have someone drive you to and from the test.
How It Is Done
An electroencephalogram (EEG) may be done in a hospital or in a doctor's office by an EEG technologist. The EEG record is analyzed by a doctor who is specially trained to diagnose and treat disorders affecting the nervous system (neurologist).
You will be asked to lie on your back on a bed or examining table or relax in a chair with your eyes closed. The EEG technologist will attach 16 to 25 flat metal discs (electrodes) to different places on your head, using a sticky paste to hold the electrodes in place.
The electrodes are connected by wires to a machine that amplifies and records the electrical activity inside the brain.
The machine records the electrical activity as a series of wavy lines drawn by a row of pens on a moving piece of paper or as an image on the computer screen.
Try to lie still, with your eyes closed during the recording, and do not talk to the technologist unless you need to. The technologist will observe you directly during the test. The usual recording time is 25-45 minutes, if a longer recording is needed, the recording may be stopped from time to time to allow you to stretch and reposition yourself.
In addition to the recording of your brain's electrical activity while you are resting, certain procedures may be done to observe how your brain responds to different forms of stimulation:
After the test, you may resume normal activities. However, if you were sleep-deprived, have someone drive you home after the test.
How It Feels
An electroencephalogram (EEG) is a painless test. You will not feel anything the ordinary during the EEG recording.
A paste is used to position the electrodes, and some paste may remain in your hair after the test, so you will have to wash your hair to remove it.
If you are asked to breathe rapidly, you may feel lightheaded or have some numbness in your fingers. This reaction is normal. It will go away within a few minutes after you start breathing normally again.
The EEG will be read by a trained neurologist. A report of the findings will be sent to the physician who ordered the test within a few days after the test.
An EEG is a recording of the electrical activity of the brain. Fluctuating electrical impulses produced by the brain are recorded and analyzed to evaluate a variety of neurological conditions.
An EEG is an important test in the evaluation of seizure disorders, metabolic disorders (liver or kidney dysfunction), nervous system disorders (encephalitis or abscess), degenerative disorders (Alzheimer’s or Parkinson’s Disease), head injuries, headaches, brain tumors, brain death, cerebral palsy, strokes and many others.
What happens during an EEG test?
Patients 18 years and older will be escorted to the testing area alone. Companions are welcome, but should plan to remain in the waiting room throughout the procedure.
Small metal discs called electrodes are attached to 22 predetermined locations on your scalp with an adhesive. Other methods of electrode application include an electrocap, special conductive paste used with small disc electrodes, or, very rarely, needle electrodes that are placed under the skin.
These electrodes detect and transmit electrical activity of your brain through wires to the electroencephalograph machine, where the signals are amplified and recorded.
In order to activate specific portions of your brain, you may be asked to hyperventilate (breathe through your mouth deeper and faster than normal) or look at a strobe light, flashing at different speeds, for a brief period of time. Most people find that the EEG test is a painless procedure.
Please follow instructions during all phases of the EEG to help ensure an accurate test. Your cooperation is essential for accurate test results. A technician will be with you throughout the procedure. The test usually takes about 1 to 1 1/2 hours.
Following the test, a technician will remove the electrodes and adhesive from your scalp. You may want to wash your hair thoroughly, though, when you get home. Your diet and activities should not be affected by the test.
The results of the EEG will be interpreted by one of our neurologists, and a report will be sent to your healthcare provider that ordered the procedure. The provider/doctor that ordered your test will provide your results to you. If the EEG test was ordered by a Minneapolis Clinic of Neurology provider, your results will be discussed with you at your next appointment.
- Sleep Studies: Most EEG tests record brain waves while you are awake and drowsy. At times, however, it is helpful for the neurologist to analyze brain activity that occurs during sleep. To encourage sleep during the EEG, you may be asked to alter your sleep schedule prior to the test.
- Ambulatory EEG: If a standard EEG does not verify seizure activity, an ambulatory, or extended, EEG may be ordered, which records brain activity for an extended period of time to more thoroughly assess a seizure diagnosis. During an ambulatory EEG, electrodes are applied to your scalp with glue and are connected to a unit worn on a belt while you go about your usual activity. You will be asked to maintain a diary of activities for the duration of the test. Ambulatory EEG tests are conducted at our Golden Valley offices.
- Video EEG: A video EEG is used at times to assist in the diagnosis of seizure activity and/or the affected brain location. During the EEG test, you are videotaped so that the neurologist can correlate your EEG tracing with your taped activities and behaviors. A video EEG test can take anywhere from a few to eight hours and are performed at our Golden Valley office.
How should I prepare for an EEG?
Wash and dry your hair and scalp before the test so that they are clean and oil-free. Do not use conditioner or hair spray.
Electrodes will need to be placed at specific locations on your scalp so we are not able to work around a hair weave.
Eat a regular meal or snack two hours before your EEG to help stabilize blood sugar, unless you’ve been instructed not to eat by your physician. If you take any medications, please ask your physician if you should take them as usual.
If your physician has ordered a sleep test, you ly be asked to adjust your sleeping schedule. Please follow the recommended adjustments to your sleeping schedule so that you find it easier to fall asleep during the test.
If you will be having a video EEG test, you will need to bring someone who can stay with you for the duration of the test. You may wish to bring VHS movies or a personal DVD player, books or other items to pass your time, as well as a bag lunch/beverage.
EEG Department Phone: (763) 287-2300, option 2
To schedule an appointment for an EEG at any of our primary offices in the Twin Cities, please contact our central scheduling at (763) 287-2300, select option 2 or send a referral and our Patient Care Coordinators will call you. We do need a physician referral prior to scheduling. EEG referrals can be faxed to (763) 302-4348 or emailed to EEG.EMG@Mpls-Clinic.com.
Minneapolis Clinic of Neurology – Golden Valley/Main Office
Minneapolis Clinic of Neurology – Burnsville Office
Minneapolis Clinic of Neurology – Coon Rapids Office
Minneapolis Clinic of Neurology – Edina Office
Minneapolis Clinic of Neurology – Maple Grove Office
The Minneapolis Clinic of Neurology provides inpatient EEG neurodiagnostic testing at Mercy Hospital, Unity Hospital and Maple Grove Hospital. In addition, we provide services at many of the outreach locations that we visit.
An electroencephalogram (EEG) is a noninvasive test that records electrical patterns in your brain. The test is used to help diagnose conditions such as seizures, epilepsy, head injuries, dizziness, headaches, brain tumors and sleeping problems. It can also be used to confirm brain death.
How does an EEG work?
The billions of nerve cells in your brain produce very small electrical signals that form patterns called brain waves. During an EEG, small electrodes and wires are attached to your head. The electrodes detect your brain waves and the EEG machine amplifies the signals and records them in a wave pattern on graph paper or a computer screen (Fig. 1).
Figure 1. A sample EEG recording showing a focal spike typical of a seizure.
There are several different ways to conduct an EEG:
- Standard EEG recording is done in the office and usually lasts an hour. You may be asked to do a sleep-deprived EEG, which requires you to have only 4 hours of sleep. Abnormal brain waves may appear when the body is stressed or fatigued. This exam usually takes 2 to 3 hours. You will be given specific instructions regarding food, drink, and medications that may need to be avoided.
- Ambulatory EEG involves wearing a portable EEG recorder on a belt around your waist for several days or weeks. The EEG recorder along with a diary you keep of daily activities and drug dosages helps the doctor relate your activity to specific EEG recordings.
- Video EEG monitoring is available in specialized centers for patients with frequent seizures or sleep disorders. You stay in the hospital and are monitored both by EEG and a video camera. This allows you to be observed during a seizure so that your physical behavior can be monitored at the same time as your EEG.
What does an EEG show?
An EEG measures electricity that your brain makes; it does NOT measure thoughts or feelings, and it does not send any electricity into your brain. It is most often used to determine the type and origin of seizures.
For example, if you have a seizure disorder, the EEG can show where abnormal activity in your brain comes from and can help distinguish between generalized or focal seizures. An EEG is of value for diagnosing epilepsy only if it detects patterns typical of epilepsy.
If it doesn’t detect the right patterns, you may still have epilepsy and ambulatory monitoring or video EEG may be necessary.
EEG can also detect abnormal brain waves after a head injury, stroke, or brain tumor. Other conditions such as dizziness, headache, dementia, and sleeping problems may show abnormal brain patterns. It can also be used to confirm brain death.
Who performs the test?
A technician can perform the test in the doctors office, a specially designed clinic, or in the hospital.
How should I prepare for the test?
- Make sure your hair is clean, freshly washed, and free from any styling products. If you have long hair, do not braid, tie, or pin it up.
- You may eat regular meals, but avoid drinks that contain caffeine for at least 4 hours before the test.
- Do not nap before the test.
- Continue taking your medicine unless your doctor tells you to stop.
What happens during the test?
You will be asked to lie on a table or sit in a reclining chair. About 20 small electrodes will be attached to your head with washable glue.
The technician may ask you to do several things during the test, such as asking you to open and close your eyes, breath deeply and rapidly (hyperventilation), or look at a flashing light.
Most of the time you will just lie still with your eyes closed.
What happens after the test?
The technician will remove the electrodes and you should wash the glue your hair.
How do I get the test results?
A neurologist, or a doctor who specializes in brain and nervous system problems, interprets your EEG. He or she will communicate directly with your referring doctor, who in turn will discuss the results with you.
Sources & links
If you have further questions about this diagnostic test, contact the doctor that ordered the test or visit:
electrode: a conductor that carries current. Can be used for diagnostic testing to receive and record electrical activity of nerves.
seizure: uncontrollable convulsion, spasm, or series of jerking movements of the face, trunk, arms, or legs.
updated > 4.2016
reviewed by > David Ficker, MD, Maureen Gartner, RN, University of Cincinnati Department of Neurology, Ohio
Mayfield Certified Health Info materials are written and developed by the Mayfield Clinic. We comply with the HONcode standard for trustworthy health information. This information is not intended to replace the medical advice of your health care provider.
An electroencephalogram (EEG) is a test used to find problems related to electrical activity of the brain.
An EEG tracks and records brain wave patterns. Small metal discs with thin wires (electrodes) are placed on the scalp, and then send signals to a computer to record the results. Normal electrical activity in the brain makes a recognizable pattern. Through an EEG, doctors can look for abnormal patterns that indicate seizures and other problems.
Why It's Done
Most EEGs are done to diagnose and monitor seizure disorders. EEGs also can identify causes of other problems, such as sleep disorders and changes in behavior. They're sometimes used to evaluate brain activity after a severe head injury or before a heart transplant or liver transplant.
If your child is having an EEG, preparation is minimal. Your child's hair should be clean and free of oils, sprays, and conditioner to help the electrodes stick to the scalp.
Your doctor may recommend that your child stop taking certain medicines before the test. It's often recommended that kids not have caffeine up to 8 hours before the test. If it's necessary for your child to sleep during the EEG, the doctor will suggest ways to help make this easier.
An EEG can be done in the doctor's office, a lab, or a hospital. Your child will be asked to lie on a bed or sit in a chair. The EEG technician will attach electrodes to different locations on the scalp using adhesive paste. Each electrode is connected to an amplifier and EEG recording machine.
The electrical signals from the brain are converted into wavy lines on a computer screen. Your child will be asked to lie still because movement can change the results.
If the goal of the EEG is to mimic or cause the problem your child is having ( seizures), he or she may be asked to look at a bright flickering light or breathe a certain way. The health care provider performing the EEG will know your child's medical history and will be ready for any issues that could come up during the test.
Most EEGs take about an hour. If your child needs to sleep during it, the test will take longer. You might be able to stay in the room with your child, or you can step outside to a waiting area.
What to Expect
An EEG isn't uncomfortable, and patients do not feel any shocks on the scalp or elsewhere. Still, having electrodes pasted to the scalp can be a little stressful for kids, as can lying still during the test.
Getting the Results
A neurologist (a doctor trained in nervous system disorders) will read and interpret the results. Though EEGs vary in complexity and duration, results usually are available in a few days.
EEGs are very safe. If your child has a seizure disorder, your doctor might want to stimulate and record a seizure during the EEG. A seizure can be triggered by flashing lights or a change in breathing pattern.
Helping Your Child
You can help prepare your child for an EEG by explaining that it won't be uncomfortable. You can describe the room and the equipment that will be used, and reassure your child that you'll be right there for support. For older kids, be sure to explain the importance of keeping still while the EEG is done so it won't have to be repeated.
If You Have Questions
If you have questions about the EEG procedure, speak with your doctor. You can also talk to the EEG technician before the exam.
Reviewed by: KidsHealth Medical Experts
EEG – Electroencephalogram
- an EEG is a test that records the small electrical signals that the brain produces all the time
- an EEG is painless and harmless
- it will take up to 1 hour and 30 minutes
EEG stands for electroencephalogram. Electro (electricity); encephalo (brain); gram (recording).
- an EEG is a test that records the small electrical signals that the brain produces all the time
- an EEG digitally records these patterns on a special computer
Who does an EEG?
Neurophysiology technicians do EEGs. They are specially trained in this field.
Why do an EEG?
An EEG can show brain wave abnormalities in children with epilepsy.
An EEG shows the electrical activity (brain waves) in your child's brain.
The EEG can show abnormalities of these brain waves – you can sometimes see these between seizures in children with epilepsy.
Some of these abnormalities are only seen in sleep. Others are obvious in the awake and drowsy states. For that reason, it's best to record the brainwaves in your child when they are both awake and asleep.
How can technicians get the most information from an EEG?
The EEG records brain waves for 20 to 45 minutes, which is only a small amount of time. Abnormalities do not occur all the time but technicianscan do things to increase the chances of picking up abnormalities during the recording time. These include:
- sleep deprivation
- deep breathing (hyperventilation)
- flashing lights (photic stimulation)
- opening and closing eyes
Technicians usually video your child during the EEG. This helps the specialist interpret the EEG. Once the specialist has finished the EEG report, they will usually delete the videos unless the video has recorded an event of interest.
Where do you go for an EEG?
There are several hospitals in New Zealand where your child can have an EEG. Your doctor will tell you which hospital to go to – you may have to travel.
How do I prepare my child for the EEG?
- your child can eat and drink normally, and take any usual medicines
- as this test takes a while, be prepared with food and drink for your child
- if your child has a special toy, or book or cuddly please bring this too – they will help reassure and settle your child
- please wash your child's hair the day before the test
Sometimes, before the EEG, your child needs to have less sleep than usual. This is called a sleep deprived EEG. Sleep deprivation does 2 things:
- it increases the chances that your child will sleep during the EEG
- it increases the chances that if there are any abnormalities they will be seen during the recording
The EEG department will let you know if they would the EEG to be sleep deprived. They will give you information about how to sleep deprive your child.
What happens at the hospital before the EEG?
- please allow plenty of time to find the department so that you arrive at least 5 minutes before your appointment time
- the technician will ask about medications, the reason your child has been sent for the test and any other relevant information which will help the doctor report the EEG
You can go with your child into the recording room
As a parent/guardian/caregiver, you will be able to go with your child into the recording room. You will be able to help the technologist get your child's full cooperation. It is best that no more than 2 adults are with your child. Generally, it is best if other children do not come as they can distract your child having the test.
Your baby or toddler will be able to sit on your lap and you can feed them. If your child is older, the technician will ask them to lie on a bed.
Tell the technician about any skin allergies
Please tell the technician if your child has any skin condition or has any allergies to skin products.
The technician will attach about 24 small silver discs to your child's head
The technician will measure your child's head. They will then mark the electrode positions with a special crayon. The technician will attach about 24 small silver discs to your child's head using either paste or tape.
They place the discs in various positions on your child's head, forehead and earlobes. They will also put one disc on one or both shoulders to record your child's heart.
Some EEG departments use a rubber cap ( a net) or some gel to keep the electrodes in place.
It will take about 15 – 20 minutes to put the electrodes on. It is very important that your child stays fairly still during the whole process, as well as during the recording.
You can read to your child while the technician puts the electrodes on, and during the recording.
It is important for your child to lie still
During the recording, the technician will ask your child to keep still and not talk.
Your child needs to open and close their eyes and breathe in and out deeply
The technician will also ask your child to open and close their eyes for short periods. Your child can practise this at home. It is important for your child to lie still and to be relaxed.
The technician will also ask your child to breathe in and out deeply and quickly for 3-4 minutes (hyperventilate). Your child may need to do this twice.
This deep breathing is very important but is quite difficult for a child so they need plenty of encouragement. You may need to do it with your child to keep them going. Breathing deeply makes you feel dizzy and light headed.
This dizzy feeling means your child is doing it well. It may be an idea to practise a little at home for 20 seconds at a time.
Your child will then have a short sleep
After the deep breathing, your child may become sleepy. This is good as the technician will dim the lights and encourage your child to sleep.
Finally, after a short sleep, the technician will flash a special light in front of your child. They will ask your child to look at the light while opening and closing their eyes when asked to.
What happens after the EEG recording?
The technician will remove the electrodes as carefully as possible using a cold liquid – it does not smell very nice but evaporates really quickly.
Your child will need another hair wash once they're at home.
How long do the EEG results take?
A neurologist will examine the recording and write a report. They will send a copy of the report to the doctor who requested the EEG as soon as possible. This should happen within several weeks.