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Electroencephalogram

(EEG)

by Editorial Staff and Contributors

En Español (Spanish Version)
 

Definition

The electroencephalogram (EEG) is a test. It is used to look at the electrical activity in the brain.

Placement of Sensors for an EEG

Copyright © Nucleus Medical Media, Inc.

 

Reasons for Test

An EEG may be done to:

  • Help diagnose seizures
  • Assess if brain function has been affected by certain conditions and diseases, such as:
 

Possible Complications

There are no major complications associated with this test.

 

What to Expect

Prior to Test

Depending on the reason for your EEG, you may be given some of the following instructions:

  • Ask your doctor whether to stop any medicines, such as stimulants, prior to the test.
  • Avoid caffeine for eight hours before the test.
  • Shampoo your hair the day of the test. Do not use hairspray or gel that day.
  • If you are having a sleep-deprived EEG, you may need to stay awake the night before the test. You should also arrange for a ride to and from the test.
  • If you are prone to seizures, arrange for a ride to and from the test.

Description of Test

You will sit in a chair or lie on a cot. Electrodes will be placed on your scalp with special gel or paste. The electrodes will record the brain's electrical activity. You will be asked to close your eyes and be still for most of the test. Depending on the reason for the test, there may be other steps such as:

  • You may be asked to breathe deeply and rapidly.
  • The technician may turn on a strobe light that sends fast pulses of light.

In some cases, the doctor will make a video recording of the test.

After Test

The technician will remove the electrodes, and you will be able to go home.

Talk to your doctor about restarting any medicines you may have stopped.

How Long Will It Take?

The test may take about one hour. In some cases, an EEG is done overnight or over a number of days. The test may be done at home or in the hospital.

Will It Hurt?

No, an EEG is painless.

Results

A specialist will review your test results. Your doctor will get a report within 1-2 weeks of your test and talk to you about the results.

 

Call Your Doctor

Call your doctor if you have a seizure disorder and you have a change in your regular seizure pattern once you have restarted your anti-seizure medicine.

RESOURCES::

Epilepsy Foundation
http://www.epilepsyfoundation.org

National Institutes of Health
http://www.nih.gov

CANADIAN RESOURCES::

Epilepsy Canada
http://www.epilepsy.ca

Epilepsy Ontario
http://www.epilepsyontario.org

REFERENCES::

EEG (Electroencephalogram). KidsHealth website. Available at: http://kidshealth.org/parent/general/sick/eeg.html#. Updated September 2008. Accessed August 31, 2012.

Seizure in adults. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated August 2, 2012. Accessed August 31, 2012.

Seizure in children. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated August 2, 2012. Accessed August 31, 2012.

Shevell M, Ashwal S, Donley D, et al. Practice parameter: Evaluation of the child with global developmental delay: Report of the Quality Standards Subcommittee of the American Academy of Neurology and The Practice Committee of the Child Neurology Society. Neurology. 2003;60:367-380.


Last reviewed September 2012 by Rimas Lukas, MD
Last Updated: 09/30/2012

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