An EEG (electroencephalogram) is a test that records the electrical activity of your brain. (The nerve cells in your brain work by carrying tiny electrical charges.)
An EEG can help your healthcare provider diagnose medical problems such as epilepsy, sleep apnea, encephalitis (infection in the brain), dementia, and brain tumors. This test is sometimes used during surgery to check the effect of anesthesia. It may be used to test for brain death in cases of severe injury or illness.
Your head doesn't need to be shaved for an EEG. Some EEG labs ask that your hair be clean and free of hair products such as hairspray or mousse. Ask your provider if there are any special instructions you need to follow. Also ask if there are any substances or medicines that you should avoid before the test.
Sometimes a sedative is given just before the test to help you relax during the EEG. In case this happens, plan to have someone drive you home after the test.
An EEG is painless and normally takes 45 minutes. During the test you will relax in a reclining chair or bed. Small metal plates (electrodes) are pasted or taped to your head. The electrodes send information to a machine that records brain waves on paper.
EEGs may be done while you are:
The EEG records how the brain responds to these changes.
If your healthcare provider suspects you have epilepsy, an EEG will usually be done while you are sleeping. You may be given a medicine to help you sleep.
You can usually go home as soon as the test is done. Ask your health care provider when and how you will get the result of your test.
This test helps your healthcare provider diagnose certain medical conditions.
There are no risks. Discuss any concerns you have with your healthcare provider.
Call your provider right away if you have any change or worsening of your symptoms.
Call during office hours if: