Electroencephalography (EEG) is an examination, in which the electrical activity of the brains is recorded. This provides information on the functioning of the brains. The registration takes place in the form of a number of graphs, the electroencephalogram.


Electroencephalography is intended for people who have diseases or symptoms, which may have something to do with the functioning of the brains. For example, epilepsy, trauma, unexplained headaches, stroke, brain tumor or infectious diseases of the nervous system. In case of diseases, the electroencephalogram can provide information about both the nature and the location of the defect.


The brains send different types of electric pulses during different activities. By watching how the pulses look like and how strong the electrical activity is, it can be examined whether the brains function normally. Electrodes on the skull of the patient measure the difference in electrical activity in the cortex (outer layer of the cerebrum) and represent this in a graph.


The patient receives a kind of cap on his or her head, containing 20 small metal electrodes, that make contact with the scalp and that capture the electric currents in the brains. The patient also gets an electrode on the ear lobes. Wires are attached to all electrodes, which transfer the signals to the measuring equipment. Apart from the electrical signals, also the heart rate is recorded.
During the examination, the patient lies still on a soft examination table. He or she is asked to occasionally open the eyes. Some tests are performed, such as sighing for a few minutes and making fists. At the end of the examination, a lamp is going to flash in various frequencies. Via the computer, a curve with lines is displayed on the monitor. The examination is painless and takes about one hour.