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Electroencephalography (EEG): Recording Brain Waves

What Is an EEG?

EEG is the name commonly used for electroencephalography (e-LEK-tro-en-SEF-uh-LOG-rah-fee). EEG is the most important test for diagnosing epilepsy because it records the electrical activity of the brain. It is safe and painless. Electrodes (small, metal, cup-shaped disks) are attached to your child’s scalp and connected by wires to an electrical box. (The wires can only record electrical activity; they do not deliver any electrical current to your child’s scalp.) The box is then connected to the EEG machine.

The EEG machine records the brain’s electrical activity as a series of squiggles called traces. Each trace corresponds to a different region of the brain. EEGs used to be recorded on paper, but computerized, paperless EEGs are now used more often.

The Pediatric Epilepsy Center at the University of Chicago Medicine Comer Children's Hospital utilizes state-of-the-art equipment, including paperless EEGs. The pediatric neurologists who work here have gone through special training in diagnosing and treating epilepsy.

What Is a Video EEG (VEEG)?

With video EEG, your child is videotaped at the same time as his or her EEG is recorded. The recording is usually carried out over several days. The doctor usually views the video and EEG images side-by-side on a split screen. In this way, your child's doctor can see exactly how your child’s behavior during seizures is related to the electrical activity in his or her brain.

Because your child is in the hospital under close supervision, we allow him or her to have some seizures, which our experts can study. The doctor may reduce or even stop seizure medicines to make seizures more likely. Other techniques include sleep deprivation, hyperventilation (very rapid or deep breathing), and exercise.

Video EEG is most helpful in determining whether seizures with unusual features are actually epilepsy, identifying the type of seizures, and pinpointing the region of the brain where seizures begin. Locating the region precisely is essential if epilepsy surgery is being considered.

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