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Electroencephalogram (EEG) Testing

Before your electroencephalogram (EEG), you may have questions about how to prepare and what will happen during the test. The information below will help answer your questions and provide you with instructions to follow before you arrive for your test. Should you need additional information, please contact Mischer Neuroscience Institute at (713) 704-2144.

What is an EEG?

An electroencephalogram (EEG) is a test that measures and records the activity of your brain. Electrodes similar to an electrode used for an electrocardiogram (EKG) are placed on your head and attached to wires. The wires allow the computer to record your brain’s electrical activity.

Why are EEGs done?

EEGs are done to help diagnose a variety of conditions:

  • To diagnose epilepsy or to see what types of seizures are happening
  • To check for problems when people lose consciousness or have dementia
  • In sleep studies to diagnose disorders such as narcolepsy
  • To find out if a person has problems in the brain, spinal cord or nervous system

How do I prepare for an EEG?

Wash your hair the night before or the day of the test, but don’t use any conditioners, hair creams, sprays or styling gels. Hair products can make it harder for the sticky patches that hold the electrodes to adhere to your scalp.

Avoid anything with caffeine on the day of the test, because caffeine can affect the test results.

Take your usual medications unless instructed otherwise.

If you’re supposed to sleep during your EEG, your doctor may ask you to sleep less or even avoid sleep entirely the night before your test.

What should I expect?

A technologist will measure your head and mark your scalp with a special pencil to indicate where to attach the electrodes. Those spots on your scalp may be scrubbed with a gritty cream to improve the quality of the recording.

The technologist will attach flat metal discs (electrodes) to your scalp using a special adhesive. Sometimes an elastic cap fitted with electrodes is used instead. The electrodes are connected with wires to an instrument that amplifies the brain waves and records them on computer equipment.

You will relax in a comfortable position with your eyes closed during the test. At various times, the technologist may ask you to open and close your eyes, perform a few simple calculations, read a paragraph, look at a picture, breathe deeply for a few minutes or look at a flashing light.

Video is frequently recorded during the EEG. Your body motions are captured by a video camera while the EEG simultaneously records your brain waves. This combined recording may help your doctor diagnose and treat your condition.

After the test, the technologist removes the electrodes or cap. If no sedative was given, you should feel no side effects after the procedure, and you can return to your normal routine.

Should you have any questions about your test, please contact Mischer Neuroscience Institute at (713) 704-2144.