You searched for: “electroencephalography”
electroencephalography, EEG
1. The recording of the electric currents developed in the brain, by means of electrodes applied to the scalp, to the surface of the brain (intracranial) or placed within the substance of the brain (depth).
2. A method of graphically recording the electric activities of the brain, particularly the cerebral cortex, with electrodes attached to the scalp.

This process is used in the diagnosis of epilepsy, trauma, tumors, and degenerations of the brain; as well as, in the study of the effects of drugs on the central nervous system and certain psychological and physiological functions.

3. Amplification, recording, and analysis of the electrical activity of the brain. The record that is produced is called an electroencephalogram.

Electrodes are placed on the scalp in various locations and the difference between the electric potential of two sites is recorded. The difference between one pair or among many pairs at a time can be determined.

The use of this diagnostic technique has proven to be very helpful in studying epilepsy and convulsive disorders and in localizing lesions in the cerebrum.

4. The process of recording brain wave activity by attaching electrodes to various areas of the patient's head with collodion (highly flammable, colorless or yellowish syrupy solution of pyroxylin, ether, and alcohol, used as an adhesive).

During the procedure, the patient must remain quiet, with eyes closed, and not talk or move.

In certain cases prescribed activities; especially, hyperventilation, may be requested by the technician.

The test is used to diagnose seizure disorders, brainstem disorders, focal lesions, and impaired consciousness.

During neurosurgery, the electrodes can be applied directly to the surface of the brain (intracranial electroencephalography) or placed within the brain tissue (depth electroencephalography) in order to detect any lesions or tumors that might exist.

This entry is located in the following units: electro-, electr-, electri- (page 30) encephalo-, encephal- (page 2) grapho-, graph-, -graph, -graphy, -grapher, -graphia (page 28)