EEG FAQs

What is an encephalogram (EEG)?

The electroencephalogram (EEG)-is a recording of the electrical activity of the brain. The brain cells communicate electrochemically, this activity enables us to think, feel and interact with the world around us. EEG is used to assist physicians in diagnosing of seizures, epilepsy and other neurological symptoms including change in awareness, confusion, starring spells, head trauma, unexplained coma, stroke, and inflammation of the brain (encephalitis). EEG provides information about the electrical functioning of the brain while MRI, CT, and Xray provide images of the brain and structures.

How are EEG’s Performed?

EEG is performed by placing highly sensitive disc electrodes on the patient’s scalp. Electrodes are positioned in specific locations on the head at measured intervals using the International 10-20 system. EEG technologists attach electrodes with a variety of methods such as paste, glue, or tape. The test is not painful, the patient can lay back (or recline) and relax. During the test the patient may be asked to take deep breaths (hyperventilate), be shown flashing lights at different speeds, or try to fall asleep. All these activations can reveal patterns that may be helpful for physician to diagnose the patient. 

The EEG procedures

Routine EEG’s are recorded for 20-30 minutes but longer recording are sometimes needed 60 minutes up to a few hours. The patient is instructed to relax (lay down or recline), keep their eyes closed, and remain as quiet as possible. EEG is performed in a dark, quiet room to help the patient relax- and fall asleep. During the procedure patient may be asked to take deep breaths (hyperventilate), be shown flashing lights at different speeds, answer questions, or try to fall asleep. All these activations can reveal patterns that may be helpful for physician to diagnose the patient. After the study is completed, patient’s head is cleaned up (often just with warm water). 
Long term monitored EEGs (LTM) are prolonged EEG tests recording brain signal for several days. These tests give physician more information about patient’s brain activity, they often include simultaneous recording of video for behavioral changes. Correlating video with EEG signal is very beneficial in proper diagnosis of seizures and localizing seizure onset zone in the brain.

Who performs EEG?

EEGs are performed by qualified neurodiagnostic technologists registered in EEG by ABRET or by trained allied neurodiagnostic professionals who proved competency in performing EEGs.