Electroencephalogram (EEG)

Because the brain is full of neurons, its activity includes many electrical signals. These “brain waves” can be measured by an electroencephalogram (EEG). 

By measuring brain waves, neurologists can tell: 

• If the brain has abnormalities.
• The location of any abnormal signals in the brain.
• How the brain responds to stimuli.

When EEG Is Needed

An EEG can be done while the patient is resting, during surgery or even while they are moving and walking. An EEG may be ordered to check for brain injury, disease or disorders or their effects. These include:

• Seizures, including epilepsy.
• Brain injury, such as after a concussion or traumatic brain injury. 
• Brain tumor.
• Sleep disorders.
• Brain inflammation (encephalitis).
• Stroke.
• Brain degeneration.

What to Expect During an EEG

The most common use of EEG is while the patient is awake and relaxing in a chair or on a bed. Then the test proceeds in a few basic steps:

1. A number of little metal discs, called electrodes are applied to your scalp. Though your hair won’t usually need to be shaved, it should be clean and dry.
2. The electrodes record your brain waves while you relax.
3. For some EEGs, some stimulation like flashing lights or reading may be required.
4. Video will record any body movements during the exam for comparison with the brain waves. 

The information recorded helps your neurologist better understand your symptoms and their cause. If you or your doctor believe you need EEG, you can reach us at (425) 635-6560 for referral and scheduling information.

Preparing for Your EEG Appointment  

• Please have hair clean and free from any mousses, oils and/or hairspray. It's best if hair is washed the day before.
• Please avoid any chemical treatments (hair coloring, relaxers and permanent waves) within 48 hours prior to your appointment.
• Please have face free from makeup or other facial products, with the exception of moisturizer.
• Please plan to come in tired. Limit the number of hours of rest the night before to half of what you typically get on a given night.
• No caffeine 5-6 hours prior to your appointment.
• It is safe to eat and drink prior to your appointment. (Except for caffeine.)

On they day of your EEG appointment, please check-in with Overlake Medical Center’s admitting department. Admitting is located in the lobby of Building 2, near Stanza's Café. Please arrive 15-30 minutes prior to your scheduled appointment time. Have a seat in the lobby once you check in, and a technician will greet you to bring you to the EEG lab.  Parking is in Garage 3.  If you're late by 15 minutes or more, the EEG department may request that you reschedule your appointment.