Definition of Electroencephalogram

Electroencephalogram: A study of electrical current within the brain. Electrodes are attached to the scalp. Wires attach these electrodes to a machine which records the electrical impulses. The results are either printed out or displayed on a computer screen. Electroencephalogram is abbreviated EEG.

Different patterns of electrical impulses can denote various problems within the brain including different forms of epilepsy. Most EEGs see only a moment in time within the brain, and can catch only gross abnormalities in function. An overnight EEG is designed to check the electrical activity in the brain of a sleep-deprived patient, increasing the chance that seizure activity will be revealed. Also available are 24- or 48-hour EEGs, which measure electrical activity over one or two days, usually using mobile EEG units.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=11199
Last Editorial Review: 2/25/2001

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