Analysis of background activity.

Analysis of EEG background activity in epilepsy has been much less used than automatic detection of paroxysmal figures. However, it would be useful to study the background activity with precision. The techniques used can belong to the time domain or the frequency domain. They make it possible to study the variations of EEG background activity as a function of the drug therapy and the type of epilepsy; some prognostic indices can then be derived for different kinds of epilepsy. It seems probable that topographic displays of background frequency bands will be very interesting in the near future. Finally, automatic analysis of sleep recordings in epileptic patients also makes it possible to test drug effects and modifications of sleep stages, as a function of the type of epilepsy.