- 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.
* * *- flat e. SYN: electrocerebral silence.
* * *elec·tro·en·ceph·a·lo·gram -in-'sef-ə-lə-.gram n the tracing of brain waves made by an electroencephalograph
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* * *elec·tro·en·ceph·a·lo·gram (EEG) (e-lek″tro-en-sefґə-lo-gram″) a recording of the potentials on the skull generated by currents emanating spontaneously from nerve cells in the brain. The normal dominant frequency of these potentials is about 8 to 10 cycles per second and the amplitude about 10 to 100 microvolts. Fluctuations in potential are seen in the form of waves, which correlate well with different neurologic conditions and so are used as diagnostic criteria. See also brain waves, under wave.
Electroencephalogram. Recordings made while the subject was excited, relaxed, and in various stages of sleep. During excitement the brain waves are rapid and of small amplitude, whereas in sleep they are much slower and of greater amplitude.
Medical dictionary. 2011.