During the Procedure

A standard noninvasive EEG takes about 1 hour. You will be positioned on a padded bed or table, or in a comfortable chair. To measure the electrical activity in various parts of your brain, a nurse or EEG technician will attach 16-20 electrodes to your scalp. Your brain generates electrical impulses that these electrodes will pick up. To improve the conduction of these impulses to the electrodes, a gel will be applied to them. Then a temporary glue will be used to attach them to your skin. No pain will be involved.

The electrodes only gather the impulses given off by your brain and do not transmit any stimulus to your brain. The technician may tell you to breathe slowly or quickly and may use visual stimuli such as flashing lights to see what happens in your brain when you see these things. The brain's electrical activity is recorded continuously throughout the exam on special EEG paper.

• Sleep EEG: During a specialized sleep EEG, you will be placed in a room that encourages relaxation and asked to fall asleep while your brain's electrical activity is recorded. The sleep EEG will last about 2-3 hours.
  
  
• Ambulatory EEG: During a specialized ambulatory (moving from place to place, walking) EEG, the electrodes are placed on your scalp and attached to a portable cassette recorder. You will be allowed to go home and resume normal activities while the EEG continuously records. The ambulatory EEG typically lasts 24 hours.