What It Is

An electroencephalogram (EEG) is a test used to detect abnormalities related to electrical activity of the brain. This procedure 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

The most common reason an EEG is performed is to diagnose and monitor seizure disorders. EEGs can also help to identify causes of other problems such as sleep disorders and changes in behavior. EEGs are sometimes used to evaluate brain activity after a severe head injury or before heart or liver transplantation.

Preparation

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 medications before the test that can alter results. It's often recommended that kids avoid 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.

The Procedure

An EEG can either be performed in an area near the doctor's office or at 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 alter the results.

If the goal of the EEG is to mimic or produce the problem your child is experiencing, 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 prepared for any issues that may arise during the test.

Most EEGs take about an hour to perform. If your child is required 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; however, 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 are typically available in several days.

Risks

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 the test 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: Steven Dowshen, MD
Date reviewed: September 2010