What It Is
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.