This is a test used to measure and evaluate electrical activity in the brain. This test uses electrodes in order to analyze the electrical impulses in the brain and are attached to the scalp with wires that send signals to a computer so that the results will be recorded. The recording of electrical impulses in an EEG look like wavy lines with peaks and valleys. This allows doctors to quickly assess whether there are abnormal patterns. Any irregularities may be a sign of seizures or other brain disorders.

The measurements provided by an EEG is used to confirm or rule out a number of conditions such as:

  • A brain tumor
  • Brain Dead (for those in a coma)
  • Dementia
  • Encephalitis (which is the inflammation of the brain)
  • Encephalopathy (this is a disease that causes brain dysfunction)
  • A head injury
  • Loss of consciousness
  • Memory issues
  • Seizures (such as epilepsy)
  • Sleep problems (such as narcolepsy)
  • Stroke

If someone is under a coma, an EEG may be performed to determine the level of brain activity. An EEG can also be used to monitor activity during brain surgery.


Steps that may be asked or performed during your examination:

  • You'll be asked to either lie down on you on a bed or a table, if the specialist in the room has a reclining chair you will be asked to sit.
  • The specialist in charge will attach several flat metal discs known as electrodes to different places on your head. The electrodes will use a special adhesive gel and is connected to wires that are furthermore connected to a computer that records the electrical activity in the brain, it then converts that electrical activity into a visual representation that can be seen on the screen.
  • During the test the specialist may ask you to do different things so that the specialist may be able to see what sort of activity your brain does at that particular moment. This includes:
    • Taking deep and rapid breaths (hyperventilate), this is usually around 20 breath movements a minute for 3 minutes or so.
    • You may be asked to look at a stimulus (e.g a flashing light called a strobe, or some pictures.)
    • If you're asked to fall asleep but are unable to do so, you may receive a sedative that will help you sleep.
    • If an EEG is performed to check up on a sleep issue, the activity in your brain may be recorded through the night.

The procedure is dependant, sometimes it may be 30 minutes and can sometimes take up to 2 hours. However, it if takes longer than an hour it may be due to the specialist being thorough and may or may not have spotted any issues. It is important to take note that after the procedure if you've had little to no sleep or were given a sedative during the procedure, then it would be recommended to have someone drive you home to while the effects wear off.


Before the test the following steps should be taken or is advised:

  • Wash your hair the night before the test, however take note not to use hair products such as conditioner, oils, sprays or gels. If you have hair extensions or weaved/braided hair consult with the doctor in charge of the test for special instructions.
  • You may need to stop taking certain medications before your test. Do not make any abrupt changes or stops in taking any medicines without consulting it through with your doctor. Inform your doctor about all the medications you're currently taking and also those you've recently stopped taking.
  • If you're required to sleep as little as possible the night before the test then be aware that it's best not to eat or drink products that will keep you awake such as caffeinated substances or energy drinks.


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