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What is EEG?
Electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. Brain cells communicate with each other through electrical impulses. An EEG can be used to help detect potential problems associated with this activity. An EEG tracks and records brain wave patterns. Small flat metal discs called electrodes are attached to the scalp with wires. The electrodes analyze the electrical impulses in the brain and send signals to a computer that records the results. The electrical impulses in an EEG recording look like wavy lines with peaks and valleys. These lines allow doctors to quickly assess whether there are abnormal patterns. Any irregularities may be a sign of seizures or other brain disorders.
An EEG is used to detect problems in the electrical activity of the brain that may be associated with certain brain disorders. The measurements given by an EEG are used to confirm or rule out various conditions, including
seizure disorders (such as epilepsy)
head injury
encephalitis (inflammation of the brain)
brain tumor
encephalopathy (disease that causes brain dysfunction)
memory problems
sleep disorders
stroke
dementia
When someone is in a coma, an EEG may be performed to determine the level of brain activity. The test can also be used to monitor activity during brain surgery.
Why is an EEG performed?
There are no risks associated with an EEG. The test is painless and safe. Some EEGs do not include lights or other stimuli. If an EEG does not produce any abnormalities, stimuli such as strobe lights, or rapid breathing may be added to help induce any abnormalities. When someone has epilepsy or another seizure disorder, the stimuli presented during the test (such as a flashing light) may cause a seizure. The technician performing the EEG is trained to safely manage any situation that might occur.
Are there risks associated with an EEG?
What do the EEG test results mean?
A neurologist (someone who specializes in nervous system disorders) interprets the recordings from the EEG and then sends the results to your doctor. Your doctor may schedule an appointment to go over the test results with you.
A neurologist (someone who specializes in nervous system disorders) interprets the recordings from the EEG and then sends the results to your doctor. Your doctor may schedule an appointment to go over the test results with you.
Normal results
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Abnormal EEG results may be due to:
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epilepsy or another seizure disorder
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abnormal bleeding or hemorrhage
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sleep disorder
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encephalitis (swelling of the brain)
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tumor
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dead tissue due to a blockage of blood flow
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migraines
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alcohol or drug abuse
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head injury
It’s very important to discuss your test results with your doctor. Before you review the results, it may be helpful to write down any questions you might want to ask. Be sure to speak up if there’s anything about your results that you don’t understand.
Abnormal results
