The brain cells talk to each other and to the rest of the body with electrical signals. An electroencephalogram (EEG) is a test that will show the electrical activity of the brain.
An EEG may be done to look for changes in brain activity after an injury or illness such as:
It may also be used to diagnose or rule out disorders of the brain such as seizures.
Certain foods, medication, or activity can affect your brain activity. Before the test:
Electrodes will be placed around your scalp for the test. Shampoo your hair the day of the test so that they attach better. Do not use hair styling products.
If you have had seizures, make sure to have a ride available to and from the test.
You will be asked to sit in a chair or lie on a bed. Electrodes will be placed on your scalp with special gel or paste. The electrodes may also be part of a cap that is slipped over your head. 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:
In some cases, a video recording of the test will be made.
The electrodes will be taken off and you will be able to go home. If you are being treated for a condition you may need to stay in the hospital longer.
The test may take about 1 hour.
An EEG may also be done over a number of days for people that are in the hospital with severe illnesses.
National Institute of Neurological Disorders and Stroke
Canadian Neurological Sciences Federation
EEG (electroencephalogram). Kid's Health—Nemours Foundation website. Available at: http://kidshealth.org/parent/general/sick/eeg.html. Updated October 2016. Accessed February 14, 2018.
Gavvala JR, Schuele SU. New-Onset seizure in adults and adolescents: a review. JAMA. 2016;316(24):2657-2668.
Seizure in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T114746/Seizure-in-adults. Updated December 30, 2016. Accessed February 14, 2018.
Seizure in children. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T550165/Seizure-in-children. Updated June 21, 2017. Accessed February 14, 2018.
Shevell M, Ashwal S, 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 February 14, 2018 by EBSCO Medical Review BoardRimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.