EEG is short for electroencephalogram. This painless test records the brain's electrical activity. Nerve cells work by carrying tiny electrical charges. Several electrodes are attatched to the person's head. These are flat devices at the ends of wires. They measure low level electricity but cannot shock the patient.

An EEG can help evaluate or diagnose:
* seizure disorders, such as epilepsy,
* brain tumors or abscesses,
* head injury,
* inflammation, such as meningitis,
* mental retardation and psychological disorders, and
* confirm brain death in terminally ill patients.

Prior to the test, the person must avoid caffeine. It is also necessary to stop taking drugs that affect the nervous system for 1 or 2 days. The test lasts about 30 to 60 minutes. The person relaxes in a reclining chair or on a bed. It is important to relax, because nervousness can change brain wave patterns. Certain disorders require an EEG during sleep. A Technician attaches 16 or more electrodes to the scalp with a special paste. The electrodes send information to a machine that records brain waves on paper. During the test, the examiner may ask the person to remain still, open or close his eyes, or breathe deeply and rapidly. They may change the brightness of light in the room. The device records how the brain responds to these changes. The brain wave recordings are available right away for interpretation. After the test the person can resume taking prescription drugs.

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