The electroencephalogram (EEG) is a non-invasive test used to evaluate brain function or disorders, or to determine brain death.
PARTS OF THE BODY INVOLVED
Scalp
REASONS FOR PROCEDURE
An EEG may be done for the following reasons:
- To diagnose epilepsy
- To diagnose brain injury
- To assess conditions and diseases that affect the brain, such as coma, mental retardation, encephalitis, cognitive impairment, brain tumors, or certain psychological disorders
RISK FACTORS FOR COMPLICATIONS DURING THE PROCEDURE
There are very few risks associated with this procedure. If you are prone to seizures, and need to discontinue medication for the test, you may be more likely to have a seizure.
WHAT TO EXPECT
Prior to Procedure – Depending on the reason for your EEG, you may be given some of the following instructions:
- Stop taking medications, such as antidepressants, stimulants, or seizure control, at least 1-2 days before the test.
- Avoid caffeine the day before and the day of the test.
- Shampoo hair and do not use hairspray or gel the day of the test.
- If you are having a sleep EEG, you may need to stay awake the night before the test. You should also arrange for a ride to and from the test.
- If you are prone to seizures, arrange for a ride to and from the test.
Anesthesia – None.
Description of the Procedure - You sit or lie in a chair or cot. Electrodes are attached to your scalp with a special gel or paste. These electrodes record the brain's electrical activity and transmit impulses to an electroencephalograph, which magnifies them and records them as brain waves on moving strips of paper. You will be asked to close your eyes and be still for most of the test. However, depending on the reason for the test, you may also be asked to breathe deeply and rapidly for 3 minutes.
After Procedure – The technician removes the electrodes. You will be advised about restarting any medications you may have stopped.
How Long Will It Take? A standard EEG takes about 1 hour.
Will It Hurt? No, an EEG is painless.
Possible Complications – None.
Average Hospital Stay – None.
Postoperative Care – None.
OUTCOME
Your test results will be interpreted by a neurologist and forwarded to your doctor. Within one to two weeks of your test, your doctor will discuss the results with you.
CALL YOUR DOCTOR IF ANY OF THE FOLLOWING OCCURS
- Change in your regular seizure pattern once restarting your anti-seizure medication
SOURCE:
Harrison's Principles of Internal Medicine, 14th ed. McGraw-Hill Company, 1998.
