Electroencephalogram (EEG)

An electroencephalogram (EEG) measures and records the electrical activity generated in your brain. Electrodes — small, flat metal disks — are attached to your scalp with wires hooking to a computer. The computer records your brain's activity and then reports it as wavy lines showing up on paper. The test is non-invasive, safe and painless.

Why would an EEG be recommended?

Your physician might recommend an EEG test to diagnose or study:

  • Epilepsy or seizures
  • Memory disturbances
  • Syncope (fainting)

How should you prepare for an EEG?

  • Arrive for your appointment with clean and dry hair, without any oils or heavy products
  • Wear comfortable clothing
  • Eat as usual, but avoid caffeine on the day of your test
  • Take your prescribed medication(s) as usual, unless your physician instructs you otherwise
  • You may be asked to arrive at the office a bit sleep-deprived, perhaps getting two to three hours less sleep than usual the night before

What can you expect during an EEG?

  • When you arrive, you may be asked a few questions about your symptoms. This information is helpful in interpreting the test and providing you with a diagnosis.
  • You'll lie down on an examination table. A technician will measure and mark your head with a grease pencil to ensure the electrodes are put in the proper place. Electrodes connected to EEG wires will be placed on your scalp using a gritty gel followed by a type of paste to affix them.
  • You'll be asked to lie quietly, open and close your eyes, answer simple questions and perhaps perform a few mental tasks such as simple math or spelling.
  • You also may be asked to do a bit of deep breathing, which could make you feel lightheaded or dizzy. This is a normal reaction and will subside once you stop the deep breathing exercises.
  • You also may be exposed to flashing bursts of light. You may see different colors or patterns during this part of the exam.
  • An EEG typically takes about 60 minutes unless your physician wants to record your brain waves while you're sleeping. In that case, the test would take longer.
  • After the test, a technician will remove the electrodes. You'll probably want to go home and wash your hair to get rid of all the adhesive. Other than that, you can return to your normal routine.

An HonorHealth doctor will interpret the recording and send the results to your doctor's office.