Temporal lobe epilepsy: a clinicopathological study with special referenceto temporal neocortical changes

The number of patients undergoing surgical treatment for pharmacoresistant temporal lobe epilepsy is rapidly increasing. While there have been many cl inicopathological studies concerning the medial structures of the temporal lobe in temporal lobe epilepsy, its lateral structures have received little attention. To examine the nature and frequency of lateral temporal lobe ab normalities that occur in temporal lobe epilepsy, 22 patients who underwent standard anterior temporal lobectomy with hippocampectomy for intractable temporal lobe epilepsy were studied. The mean ages at the onset of seizure and at surgery were 15.9 years and 27.7 years, respectively. The electrocli nically determined epileptogenic zones were the medial structures of the te mporal lobe in 16 patients and the lateral in six. There was histologic evi dence of hippocampal sclerosis in 12 of the 16 patients with medial onset s eizures and in three of the six patients with lateral onset seizures. The l ateral structures of the temporal lobe showed variable degrees of histologi cal abnormalities in 21 patients. Among these abnormalities, heterotopic wh ite matter neurons were observed in six of the 16 medial patients and in al l the lateral patients. Glial changes were also common abnormalities, and o ften glial fibrillary acidic protein (GFAP)-positive astrocytes were presen t over the entire temporal lobe. In addition to hippocampal sclerosis, cere bral microdysgenesis and gliosis in the lateral structures of the temporal lobe may have a significant role in epileptogenesis of temporal lobe epilep sy.