Electroencephalography (EEG)

Synonyms in a broader sense

electroencephalography, electroencephalogram, (ge)brain wave measurement, measurement of brain waves

Use in medicine

The EEG is an important measure that is often used in neurological examinations.


With the help of electroencephalography (EEG), statements can be made about the basic electrical activity of the human brain, about spatially delimited brain activities (focal findings) and about convulsive activities (epilepsy). For certain suspected diagnoses (e.g. epilepsy), electroencephalography is indicated as a diagnostic procedure. However, an inconspicuous electroencephalogram is no guarantee for the exclusion of a certain suspected diagnosis.

For further clarification, modern imaging techniques (magnetic resonance imaging of the head, computer tomography) are therefore often used. However, a “normal” electroencephalogram can provide important information for neurological diagnosis. In the event of brain death (zero line), the electroencephalogram shows no electrical activity for at least thirty minutes, which represents an irreversible loss of brain function. Furthermore, electroencephalography cannot be used to make any statements about the patient’s personality traits, character or intelligence.


An EEG examination (electroencephalography) is performed especially when the following suspected diagnoses are present:

  • EpilepsyEpilepsy
  • Encephalitis (inflammation of the brain)
  • Metabolic diseases
  • Brain damage
  • Brain decomposition processes (Creutzfeld-Jakob)
  • Sleep disorders
  • Disturbances of consciousness (coma)
  • Brain deathBrain death

Risks, complications, disturbances

Contrary to the widespread assumption that in electroencephalography the patient is “electrocuted”, it must be emphasized that in this procedure only the weak potential fluctuations of nerve cells of the brain flow to the EEG devices, but no current from the device to the electrodes. The procedure of electroencephalography is therefore risk-free and side effects are not known. During the recording of the electroencephalogram, it is possible that the electroencephalogram is not usable due to heavy sweating or strong movements, for example. In addition, washed hair is helpful for a good recording of an electroencephalogram (EEG), since the fat on the scalp can worsen the transmission between the surface of the head and the electrode.