Electroencephalogram (EEG) Tests

An electroencephalogram (EEG) measures the electrical signals of your child’s brain through small button electrodes that are placed on your child's scalp. Experts in neurology have studied EEG for many years and report that it is a safe procedure, with no apparent risks.

There are three types of EEGs:

  • Traditional EEG: Happens in a clinic setting with about 25 electrodes.
  • Dense Array EEG: Happens in a clinic setting with about 250 electrodes.
  • Ambulatory EEG: Happens when a child is in his normal daily setting. Electrodes are put on the scalp and the patient is given a back pack that records the test results over several days.

Your child’s doctor will help decide which EEG is right for him. Learn more about each one:

Traditional EEG

Prepare for the test

It is important to follow these directions to get a good reading. If not, we might have to repeat or reschedule your child’s appointment.

Your child needs to be sleepy for the test.

  • Keep your child up 2-3 hours later than usual the night before the test.
  • Get him up 2-3 hours earlier than usual the morning of the test.
  • Children over 3 years of age should not sleep more than 5 hours the night before the test. 
  • Do not let your child nap the day of the test.

Your child's physicians will give you instructions about when your child can eat before and after the procedure.

  • Your child may eat or drink a regular diet before the test, but may not have foods or drinks with caffeine (such as sodas, coffee or tea) or anything that is high in sugar. Natural sugars such as fruit are OK.
  • If your baby still takes a bottle, please bring full bottles with you. 
  • Wash and rinse your child’s hair the night before the test. Do not use any oil, gel, or hairspray. If your child's hair is long, do not braid or put it up. No hair extensions please. 
  • Bring a comfort item such as a pacifier or blanket if needed. If your child is a baby or toddler, bring diapers with you.

Bring a list of all the medications (dose and schedule) your child takes.

  • If your child is taking medicine, give it at the regular time if this is at least 2 hours before the test time.
  • If the medicine is due during the 2 hours before the test, check with your doctor to see if it should be given early or held until after the test.

Arrive at the hospital 30 minutes early to allow time to park and register.

  • The test can take as long as an hour and a half. If you are more than 15 minutes late, we might need to reschedule your child’s appointment.
  • Bring money for parking (Children’s Healthcare of Atlanta does not validate). 

What to expect

To get the maximum information from this test, your child's physician will try to record EEG during wakefulness and sleep.

  • A trained, registered neurophysiology technologist will perform the test.
  • Your child will be asked to lie down on a bed or stretcher. The technologist will explain the procedure to you and your child.
  • The EEG technologist prepares your child’s head for wires called electrodes (small, flat, round discs) that will be placed on your child’s scalp. The technologist measures your child's head and makes small marks on the scalp with a washable marker or pen. Each marked area is rubbed with a gritty lotion so the electrodes transmit well. Glue is put on the electrodes, which are applied to each of the marked spots on the scalp. We may wrap your child’s head in gauze to hold the electrodes in place. The electrodes do not hurt or shock your child. 
  • The electrodes are connected to the EEG machine and the test begins. The machine records the electrical activity of the brain. 
  • After the technician checks all the sensors, the technician will take the first reading while your child is awake, your child will breathe quickly for three minutes for the next part, we will turn out the lights, and your child will sleep for 10 to 15 minutes and when your child wakes up, the technician will use flashing lights to test his reaction. He can keep his eyes closed—as long as he does not go back to sleep. 
  • The test can take as long as an hour and a half. If your child’s doctor asks for a video EEG to give more time to study the brain waves the procedure may take longer. It may last six to eight hours.
  • Your child is usually videotaped during the EEG. 

Dense Array EEG

The dense array EEG is a crucial tool in the evaluation of epilepsy. Just as magnetic resonance imaging (MRI) and computed tomography (CT) allow a structural image of the brain, dense array EEG is a way to electrically image the brain.

The dense array EEG is an important tool for finding abnormal electrical activity in children who are candidates for epilepsy surgery, such as seizures.

The dense array EEG measures and records the brain’s electrical activity by using up to 256 electrodes. By placing this many electrodes at key points on the patient’s head, doctors are able to get a good approximation of where the child's seizures start.

The seizures can be seen by the changes in the normal pattern of the brain’s electrical activity.

Difference between a traditional EEG and a dense array EEG

A dense array EEG has:

  • More complete coverage of the head: The dense array EEG uses more electrodes and up to 256 channels, compared to the 19 to 21 channels used by traditional EEG systems. This provides better accuracy and localization at the source of the activity.
  • Quick application time: Electrodes are arranged in a web-like structure, called the Geodesic Sensor Net. The electrodes can be applied in approximately 30 minutes.
  • Increased patient comfort: The dense array EEG experience is virtually painless because there is no abrasion to the scalp.

Ambulatory EEG

An ambulatory electroencephalogram (EEG) measures the electrical signals of your child’s brain while he is doing his everyday activities. These include playing with friends, watching TV and sleeping. Your child will carry home a special recorder in a backpack to record his brain’s signals.

Prepare for the test

It is important to follow the directions to get a good reading. If not, we might have to repeat or reschedule your child’s appointment.

  • Wash and rinse your child’s hair the night before the appointment. Do not use any oil, gel, or hairspray. If your child's hair is long, do not braid or put it up. No hair extensions please. 
  • Dress your child in a button-down shirt.
  • Allow your child to eat and drink as usual.
  • Give your child all his daily medicine, unless otherwise instructed by your doctor. Bring a list of all the medications (dose and schedule) your child takes.
  • Arrive at the hospital 30 minutes early to allow time to park and register. 
  • Setting up the test takes about an hour. If you are more than 15 minutes late, we might need to reschedule your child’s appointment.
  • Bring money for parking (Children’s Healthcare of Atlanta does not validate). 

What to expect

  • A trained, registered neurophysiology technologist will apply the electrodes and setup the equipment.
  • The EEG technologist prepares your child’s head for wires called electrodes (small, flat, round discs) that will be placed on your child’s scalp. The technologist measures your child's head and makes small marks on the scalp with a washable marker or pen. Each marked area is rubbed with a gritty lotion so the electrodes transmit well. Glue is put on the electrodes, which are applied to each of the marked spots on the scalp. We may wrap your child’s head in gauze to hold the electrodes in place. The electrodes do not hurt or shock your child. 
  • The electrodes are connected to the EEG machine and the test begins. The machine records the electrical activity of the brain. Your child will carry home this machine in a backpack to record his brain’s signals.
  • You will need to help during the recording by keeping a record of your child’s episodes and by pressing the “event” button if your child has any of the signs of his condition. This will help us notice important changes. 
  • Your child should not chew gum or candy during the test.

After the one- to three-day test, your child will return to the hospital. The technologist will:

  • Remove the electrodes and wires. The glue will be washed off with warm water and a wash cloth. If the glue does not come all the way off, you may need to wash your child’s hair at home. 
  • Give you any special instructions you may need and tell you when you may leave.
  • A neurologist will read the EEG and talk to your child's doctor about the results.

Contact our neurophysiology team

  • Scottish Rite: 404-785-2046
  • Egleston: 404-785-6065
  • Children's at Forsyth: 404-785-2046
  • Children's at North Druid Hills: 404-785-6065