Spread of epileptic seizure activity in humans.

A computer-augmented approach to ictal EEG analysis has been developed. A method for determining both the predictability of one signal from another and the time delay between those two signals--the average amount of mutual information (AAMI) method--has been applied to representative seizures of two patients with focal-onset seizures and one patient with generalized seizures. High AAMI values characterized the EEG derived from the sites of the epileptic foci. AAMI values were high in all sampled brain areas in the patient with generalized seizures. Time delays were not consistent in any subject. The results indicate that the AAMI technique can differentiate focal from generalized seizures and identify the site of seizure onset.