CLINICAL AND ELECTROENCEPHALOGRAPHIC EVIDENCE FOR SITES OF ORIGIN OF SEIZURES WITH DIFFUSE ELECTRODECREMENTAL PATTERN

A diffuse electrodecremental ictal pattern (DEP) has been associated w ith tonic seizures and, less often, with other forms of epilepsy and h as been considered to reflect a generalized seizure disorder of diffus e cortical or subcortical (brainstem) origin. In some seizures associa ted with DEP, however, focal ictal manifestations have been observed. We reviewed the records of all patients admitted to our seizure monito ring unit for 3 years and detected 39 patients with seizures associate d with DEP. In 23 of 39 patients, clinical ictal behaviors resembled s eizures of unilateral supero/mesiofrontal lobe origin and interictal E EG showed a prominent unilateral frontal component. Nine of 39 had com plex absences (CA)/complex partial seizures (CPS); 4 of them were of u nilateral frontal lobe origin. Seven of 39 patients had tonic or atoni c seizures. Seven patients were studied further with subdural electrod es. Ictal onsets showed a high-frequency frontal lobe discharge. We co nclude that in a subgroup of patients a generalized electrodecremental pattern on scalp EEG results from a regional cortical high-frequency ictal discharge originating in a single frontal lobe.