Electroencephalography (EEG)

Electroencephalography (EEG)

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Electroencephalography (EEG)

Electroencephalography (EEG) is a test that measures your brain wave activity. It is used to assess your brain function.

Twelve parallel lines showing normal EEG waveforms. Lines are regular, repeating pattern of small peaks and valleys.

What Is EEG Used For?

Your doctor may order this test to check for seizures or other brain problems. For this test, small metal disks (electrodes) are attached to the scalp with glue, or with water-based gel or paste. During the test, wavy lines (waveforms) appear on a screen or on paper. They will be studied to assess your brain function. In some people who are prone to seizures, parts of this test may slightly increase their chance of having a seizure. Sometimes it is necessary to repeat an EEG with sleep deprivation.

Before Your Test

Prepare for your test as instructed. Wash and dry your hair. But don't use any hairstyling products. Your scalp and hair should be clean and free of excess oil. Take your routine medications, unless told not to. You may be asked to sleep during the EEG. To help you do this, you may be told to stay up all or part of the night before the test. Or, you may be given medication to help you sleep during the test. If so, someone will need to drive you home after the test. Your test will take about 90 minutes. Arrive with enough time to check in.

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For your safety and for the success of your test, tell the technologist about:

  • Any medications or herbs you take

  • Any seizures you may have had in the past

  • If you are or could be pregnant