Electroencephalogram - EEG - for migraine diagnosis

Reviewed by: HU Medical Review Board | Last reviewed: August 2014

The electroencephalogram, or EEG, looks like something out of a science fiction movie. One or two dozen small, metal discs attached to the scalp to record electrical activity in the brain. This test is usually only given if the migraine sufferer has seizures and epilepsy is suspected. The EEG can detect or rule out other disorders that may be causing the migraine symptoms.

Why have an EEG for migraines?

An EEG can detect or help find the cause of

  • Epilepsy or other seizure disorders
  • Brain tumors
  • Head or brain injuries
  • Certain dysfunctions in the brain
  • Stroke
  • Brain or head inflammation
  • Bleeding, hemorrhage in the brain
  • Certain sleep disorders
  • Certain types of memory loss
  • Dementia

How do EEGs work?

The EEG can be conducted in the doctor’s office, hospital or laboratory.

You will need to lie on your back or recline in a chair. Flat, metal discs containing sensors and called electrodes are attached to the scalp with an adhesive or you may be asked to wear an elastic cap with the electrodes already attached. Wires leading from the electrodes record brain waves, which appear as squiggly, zigzag lines. The test takes 30 minutes to an hour to complete. During the test you may be asked to sleep, relax, close your eyes, read or look at a bright flashing light. The EEG records your brain waves, or the brain's electrical activity.

For eight hours before the test, do not eat or drink anything containing caffeine. You should also speak with your doctor about any medications you take. Because the electrodes will go directly on your scalp, you will likely be told to wash your hair the night before and not to use any oils, conditioners or creams on your hair or scalp.

Because there is no specific test a doctor can use to diagnose a migraine, like all other tests, the EEG is used to rule out other causes for the migraine symptoms. The best way to help your migraine doctor diagnose migraines is to keep a detailed account of each and every migraine attack. This record should be in your migraine journal, which lists all of your migraine symptoms, what you were doing before the symptoms surfaced, how long they last and the severity of the symptoms.

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