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    Diagnosing Migraines and Headaches With an EEG

    An EEG, or electroencephalogram, is a test that records the electrical signals of your brain. Electrodes, or sensors, that go on the scalp detect the signals and send them to a polygraph machine that records the activity.

    Why Use an EEG Test for Headaches?

    EEGs are not a standard part of a headache exam. But your doctor may order one to look for signs of seizures, which can cause symptoms similar to those of migraines or other types of headaches. Some people also have seizures with their headaches.

    An EEG can show that something’s not right in the brain, but it doesn't necessarily pinpoint the exact problem that might be causing a headache.

    How Does an EEG Work?

    Your brain cells create electrical signals that are picked up by the electrodes and sent to a polygraph. The machine illustrates them in separate graphs on moving paper using an ink pen or on a computer screen.

    How Do I Prepare for an EEG?

    • Let your doctor know about any medications you're taking before the test.
    • Wash your hair the night before the test. Don't use hair cream, oils, or spray afterward.

    What Happens During an EEG?

    • You’ll lie down on the exam table or bed while the medical team places about 20 electrodes on your scalp.
    • The team will ask you to relax and lie first with your eyes open, and then closed.
    • You may be asked to breathe deeply and rapidly or to stare at a flashing light -- both of these activities produce changes in brain-wave patterns.

    What Happens After an EEG?

    • Your care team will remove the electrodes and wash off the glue that held them in place with acetone. You may have to use extra acetone (nail polish remover) at home to completely remove the glue.
    • Unless you're actively having seizures or your doctor tells you not to, you may drive home. If you had the EEG overnight, you should arrange to have someone drive you home.
    • If you stopped taking antiseizure medication for the EEG, you can usually start taking it again. Talk to your doctor.
    • A doctor who specializes in brain diseases, called a neurologist, will examine the brain-wave pattern in the EEG recording for anything unusual. Then your doctor will go over the results and what they mean for you.

    WebMD Medical Reference

    Reviewed by David T. Derrer, MD on July 27, 2014

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