[Ambulatory monitoring of the EEG (A/EEG). Guidelines, methodology and indications]

Ambulatory monitoring of EEG by means of a cassette recording (A/EEG) allows cerebral electrical activity or other biological signals to be recorded during long periods, not less than 24 hours, with the patient being free to move around in his usual surroundings or in the hospital.

The recordings are made using a system of electrodes, recording apparatus and software.

The A/EEG is useful in the study of various diagnostic procedures, basically in the diagnosis and characterization of epilepsy. It is also useful in presurgical evaluation of patients with drug-resistant epilepsy in whom surgical treatment is being considered. In these cases, the possibility of prolonged monitoring allows some of the patient's crises to be recorded, which is very useful in finding the site of the lesion. It is also useful when studying patients with hypersomnia or disorders of the wakefulness-sleep cycle. It is complementary to multiple sleep latency tests (TLSM) and polygraphic recordings of nocturnal sleep, since it allows the quantity, duration and type of sleep to be recorded during prolonged monitoring for more than 24 hours.