An electroencephalogram is a test to measure the electrical activity of the brain.
Alternative Names
Electroencephalogram; Brain wave test; Epilepsy - EEG; Seizure - EEG
How the Test is Performed
The test is done by an electroencephalogram (EEG) technologist in your doctor's office or at a hospital or laboratory.
The test is done in the following way:
- You lie on your back on a bed or in a reclining chair.
- Flat metal disks called electrodes are placed all over your scalp. The disks are held in place with a sticky paste. The electrodes are connected by wires to a recording machine. The machine changes the electrical signals into patterns that can be seen on a monitor or drawn on paper. These patterns look like wavy lines.
- You need to lie still during the test with your eyes closed. This is because movement can change the results. You may be asked to do certain things during the test, such as breathe fast and deeply for several minutes or look at a bright flashing light.
- You may be asked to sleep during the test.
If your doctor needs to monitor your brain activity for a longer period, an ambulatory EEG will be ordered. In addition to the electrodes, you will wear or carry a special recorder for up to 3 days. You will be able to go about your normal routine as the EEG is being recorded. Or, your doctor may ask you to stay overnight in a special EEG monitoring unit where your brain activity will be monitored continuously.
