Electroencephalogram (EEG)

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KEY POINTS

• An EEG is a procedure that records the electrical activity in your brain.
• It can help check for medical problems, such as epilepsy, sleep apnea, brain infection, or brain tumors.
• An EEG is painless and normally takes 45 minutes. You can usually go home as soon as the procedure is done.

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What is an EEG?

The nerve cells in your brain work by carrying tiny electrical charges. An electroencephalogram (EEG) is a procedure that records this electrical activity in your brain.

When is it used?

An EEG can help your healthcare provider diagnose medical problems, such as epilepsy, sleep apnea, dementia (the loss of the ability to think, remember, reason, and plan), brain infection, and brain tumors. This procedure is sometimes used during surgery to check the effect of anesthesia. It may be used to test for brain death in cases of severe injury or illness.

How do I prepare for an EEG?

• You may or may not need to take your regular medicines the day of the procedure. Tell your healthcare provider about all medicines and supplements that you take. Ask your provider if you need to avoid taking any medicine or supplements before the procedure.
• Tell your healthcare provider if you have any food or medicine allergies, or if you have a pacemaker.
• Ask if there is anything you should avoid before the procedure, like smoking cigarettes or any food or drinks containing caffeine.
• On the day of the procedure, take a shower to remove oil from your hair. Some EEG labs ask that your hair be clean and free of hair products, such as hairspray or mousse.
• You may be given medicine before the procedure to help you relax during the EEG. In case this happens, plan to have someone drive you home after the procedure.
• Follow any other instructions your healthcare provider gives you.
• Ask any questions you have before the procedure. You should understand what your healthcare provider is going to do. You have the right to make decisions about your healthcare and to give permission for any tests or procedures.

What happens during the procedure?

An EEG is painless and normally takes 45 minutes or may be done as part of an overnight sleep test. During the procedure you will relax in a reclining chair or bed. Small metal plates (electrodes) will be pasted or taped to your head. The electrodes will send information to a machine that records your brain waves on paper.

EEGs may be done while you are:

• Sleeping (You may be given a medicine to help you sleep.)
• Resting with your eyes closed
• Resting with your eyes open
• Breathing rapidly (and just after)
• Looking at a flashing light

The EEG records how the brain responds to these different situations.

You may have a video EEG instead. During a video EEG, you are watched on a video screen for several hours. This allows healthcare providers to see your brainwave activity when you have a seizure.

What happens after the procedure?

You can usually go home as soon as the procedure is done.

Ask your healthcare provider when and how you will get the result of your procedure.

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

What are the risks of this procedure?

There are no risks. Discuss any concerns you have with your healthcare provider.