[Basic techniques of electroencephalography: principles and clinical applications]

The electroencephalogram is a technique for the functional exploration of the central nervous system (CNS). It is a relatively old technique but even today it continues to be a tool of great assistance to the clinician in diagnosing and treating certain pathologies, such as epilepsy, encephalopathies, alterations to the state of consciousness, CNS infections, etc. On the other hand, it is a diagnostic tool whose applications are expanding in combination with other neurophysiological techniques, such as in the field of the study and diagnosis of sleep pathology (polysomnography, multiple sleep latency test...) and in intraoperative monitoring together with somasensory evoked potentials. This article describes the basic techniques of electroencephalography, with special emphasis on its main clinical applications and on future perspectives.