Electroencephalogram Test

Submitted on March 27, 2012

The electroencephalogram (EEG) is a test that measures brain activities. For this test, electrodes are attached to the head of the patient. These electrodes help in mapping the electrical activities in the brain. Since these electrodes are connected to computers by wires, a doctor can monitor the brain waves of the person. The electrical activity of the brain appears as wavy patterns on a paper which is attached to the machine. If the patient experiences certain abnormalities in the electrical activities of the brain, the waves become sharper. Such changes can easily be distinguished from normal brain activity.

Electroencephalogram Test Reasons

The electroencephalogram is primarily ordered to diagnose epilepsy. EEG can help determine the kind of seizures that occur. It can also help check for problems that cause dementia and unconsciousness. Also, if there has been a change in consciousness, the EEG can help understand the chances of the person’s recovery.

EEG is also often conducted on a person who is in a coma. This is done to help find out if the person is brain dead. When a person receives general anesthesia, an EEG may be taken to monitor the brain activity. This is especially done in the case of a brain surgery. Other cases in which electroencephalograms may be ordered are for sleep disorders like narcolepsy, physical problems in the brain, and various mental health problems.


Though there are not many preparations to be made before taking an EEG test, you should discuss with your doctor, the use of any muscle relaxants, sedatives, sleeping aids, or tranquilizers at least a day before you take the test. Since these medicines help decrease brain activity, they may have an adverse effect on the test.

On the day of the test, do not eat or drink anything that will have an effect on the brain. Food and beverages that contain coffee should be especially avoided. Stay away from tea, cola, coffee, and chocolates for at least 8 hours before the test. On the day of the test, make sure that you shampoo your hair thoroughly and that your scalp is completely clean. Do not use any hair sprays, lotions, or creams on your scalp after shampooing. This is important because the electrodes have to be attached to your scalp, and chemicals in the hair or scalp can affect the test.

The doctor will put you to sleep during the test so that the electrical activity of the brain can be mapped carefully. The electroencephalogram results are based on the behavior of all four kinds of brain waves.