Electroencephalography - Definition

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Electroencephalography, or EEG, is a painless exam which allows the measurement of electrical activity in the brain. It is achieved through the aid of electrodes, placed on the scalp; these record the variations in the electrical potential of neurons, which express cerebral activity. This activity is transcribed by a machine in a graphic representation, which can then be interpreted by a neurologist. EEG is performed when certain neurological illnesses are suspected, such as epilepsy, encephalopathies, infectious or inflammatory brain diseases, but also sleep disorders. In this last case, the EEG takes place during an overnight hospitalization, during which the patient is equipped with electrodes. Electroencephalography may also be used to confirm the state of death, called encephalic death, or "brain death": in this case, EEG displays a perfectly flat drawing.