Electrophysiological study of intractable epileptogenicity in human epilepsy: clinical usefulness of ictal DC shifts and cavernous sinus EEG]

In order to clarify the clinical and electrophysiological features in intractable epileptogenicity in human epilepsy, we applied the new techniques, ictal DC shifts and cavernous sinus EEG recording, for presurgical evaluation of patients with intractable partial epilepsy. (1) Ictal DC shifts were successfully recorded with subdural electrodes in 8 patients with intractable neocortical epilepsy, and an analysis of ictal DC shifts would add useful information to delineate an epileptogenic area. Scalp-recorded ictal DC shifts were also investigated in 3 patients with intractable neocortical epilepsy. It also delineated the epileptogenic area, but it was vulnerable for artifacts. (2) By using the techniques of intravascular EEG recording, we recorded EEG from the bilateral cavernous sinus (cavernous sinus EEG) in patients with intractable temporal lobe epilepsy. Cavernous sinus EEG well sensitively recorded interictal, also ictal in selected patients, epileptiform discharges which arose from the mesial temporal structure even though they were not recorded by scalp electrodes. It is concluded that the above two techniques are clinically useful for delineating an epileptogenic area in patients with neocortical epilepsy and temporal lobe epilepsy.