Electroencephalography (encephalon = brain), or EEG, involves recording all the electrical activity generated by the brain from electrodes placed on the scalp surface. The test is used to detect problems related to electrical activity of the brain. An EEG tracks and records brain wave patterns. It is used to help diagnose the presence and type of seizure disorders, to look for causes of confusion, and to evaluate head injuries, tumors, infections, degenerative diseases, and metabolic disturbances that affect the brain. It is also used to evaluate sleep disorders.