Electroencephalogram (EEG)

An electroencephalogram is a test during which the electrical signals of the brain are recorded. This electrical activity is detected by electrodes, or sensors, placed on the patient's scalp and transmitted to a polygraph that records the activity.

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EEGs are not a standard part of a headache evaluation. However, an EEG might be performed to rule out other conditions, such as epilepsy. An EEG can indicate a malfunction of the brain, but it does not usually pinpoint the exact problem that might be causing a headache.

Before an EEG:

• Discuss any medicines you are taking with your doctor prior to your procedure.
• Wash your hair the night before the test. Do not use hair cream, oils, or spray on your hair.

During the EEG, you lie down on the examining table or bed while about 20 electrodes are attached to your scalp. You are asked to relax and lie first with your eyes open, then closed. You might be asked to breathe deeply and rapidly, or to stare at a flashing light. Both of these activities produce changes in the brain-wave patterns.

Electrical signals produced by the brain neurons are picked up by the electrodes and transmitted to a polygraph, where they produce separate graphs on moving paper using an ink writing pen or on a computer screen.

A neurologist examines the EEG recording for abnormalities in the brain-wave pattern, which might indicate a disease of the nervous system.