How does an eeg work?

Electrical recording: In the same way an ekg measures electrical activity from the heart, an EEG measures activity from the brain. Electrodes are placed on the scalp and the patient lies quietly while brainwaves are recorded. Sometimes, hyperventilation and/or flashing lights are used to evoke different responses. It is important to relax, as electrical activity from muscle can swamp the signals from the brain.

Records brain: Electrical activity occurs thruout the body, and like an electrocardiogram recording heart activity, small discs are taped to specific areas of the scalp, and pickup underlying electrical impulses from brain activity. The rhythms vary during sleep and waking, and are compared to normal expectations. Diffuse slowing may correlate with diffuse problems, and paroxysmal activity may indicate seizure.

Captures brain waves: Scalp electrodes are placed on designated brain areas. They are connected to amplifiers and to computers, which records brain electrical activity, for a minimum of 20 minutes. Information is filtered and displayed on a computer screen. It is interpreted by a neurologist. Different brain waves may be abnormal or normal. Eeg may be used to detect seizures, or other non-seizure abnormalities.