Clinical Significance of Secondary Epileptogenesis

: A possible existence of secondary epileptogenesis in humans was examined encephalographically and clinically. In the study of 128 patients with temporal foci who were followed up for about five years, the EEG foci changed from unilateral to bilateral (in 25/84) and from bilateral to unilateral (in 17/44). After status epilepticus, a new focus was found encephalographically in addition to the previous foci in one of the patients. The patients with bitemporal foci were found to be more therapy-resistant than those with a unitemporal focus. The mode of evolution of partial seizures was investigated in long-term histories of four patients with visual seizures and complex partial seizures who had occipital and temporal foci independently in the interictal EEG. In one patient the visual seizure at onset combined with a complex partial seizure after the fifth year, although only former seizure events had been documented on videotape. Through careful observations of a number of simultaneous video recordings of clinical and encephalographic features, not one patient showed two different partial seizures originating at separate foci. Therefore, we failed to obtain the definitive evidence of clinieoencephalographic secondary epileptogenesis, despite the fact that the existence of encephalographic secondary epileptogenesis seemed to be possible.