[Long-term monitoring].

The electroencephalography (EEG) keeps its essential role in the differential diagnosis of epileptic and non-epileptic seizure disorders and in the classification of the different types of epilepsies and epileptic seizures, mainly due to its unique capability to directly show epileptic malfunction. The routine EEG usually records the EEG between seizures (interictal EEG) and remains a cost effective, highly specific, but not very sensitive method in epileptology. However, a diagnosis based on clinical data and routine EEG alone if often difficult and 20-30% of patients referred to an epilepsy centre due to medical refractory seizures do not have epilepsy. The different methods of long-term monitoring (cable and radio telemetry, ambulatory EEG monitoring) can continuously record EEG and other biosignals for many hours up to several days and allow a direct assessment of seizures (ictal EEG). In combination with the video-recorded symptomatology, these methods establish a precise diagnosis and follow-up of uncertain seizure disorders in the majority of cases. Although technical and personnel investment is relatively high the method used in expert hands is efficient, accepted and cost effective.