Table of Contents
- Overview
- Results
- Risks
- Prevention
- Images
Electroencephalogram; Brain wave test
Normal Values
Brain electrical activity has certain frequencies (the number of waves per second) that are normal for different levels of consciousness. For example, brain waves are faster when you are awake, and slower when you're sleeping. There are also normal patterns to these waves. These frequencies and patterns are what the EEG reader looks for.
What abnormal results mean
Abnormal results on an EEG test may be due to:
- An abnormal structure in the brain (such as a
brain tumor ) - Attention problems
- Tissue death due to a blockage in blood flow (cerebral infarction)
- Drug or alcohol abuse
- Head injury
- Inflammation of the brain (
encephalitis ) - Hemorrhage (abnormal bleeding caused by a ruptured blood vessel)
- Migraines (in some cases)
- Seizure disorder (such as epilepsy or
convulsions ) - Sleep disorder (such as
narcolepsy )
Note: A normal EEG does not mean that a seizure did not occur.
Previous Section
Review Date: 03/21/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of
Physician Assistant Studies, University of Washington, School of
Medicine; Luc Jasmin, MD, PhD, Department of Neurosurgery at
Cedars-Sinai Medical Center, Los Angeles, and Department of Anatomy
at UCSF, San Francisco, CA. Review provided by VeriMed Healthcare
Network. Also reviewed by David Zieve, MD, MHA, Medical Director,
A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
