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.
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.
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.