Clinical and electrophysiological diversity of the mesial temporal lobe epilepsy confirmed by stereotactic electroencephalogram

Objective To study the diversities of imaging, symptoms, electrophysiology and clinical value of the stereoelectroencephalography(SEEG) in patients with mesial temporal lobe epilepsy. Methods Eight patients with intractable epilepsy in Epilepsy Center of Yuquan Hospital of Tsinghua University who underwent mesial temporal lobectomy were recruited in this study, and their epileptic foci could not be accurately positioned. Therefore stereotactic brain electrodes were implanted, and their usual attack originated from mesial temporal lobe structure were confirmed. There was no seizure in the one year follow-up. Results Symptoms of the eight patients behaved differently, and the onset of the seizures in scalp electroencephalograph or SEEG showed diversities. Epileptic discharges were found originated from the mesial temporal lobe after implanting electrodes: in the early stage of discharges, four cases had the conduction to insular lobe structure; two cases had the conduction to contralateral mesial temporal lobe; one case had the conduction to retrosplenial cortex; one case had the conduction to parietal lobe; one case had the conduction to frontal lobe and rapid generalization (one case had the conduction to insular lobe and contralateral mesial temporal lobe meanwhile). Conclusions There is difference in clinic, imaging and electrophysiology of the patients with mesial temporal lobe epilepsy. The non-specificity can be explained by the evolution of the intracranial electroencephalography, which can help us know its network conduction pattern. Insular lobe is the most common conduction approach of mesial temporal lobe epilepsy in early stage. SEEG can be used as a microinvasive, accurate preoperative localization method, which can help us to locate accurately and understand the discharges and conduction mode. Key words: Electroencephalography; Epilepsy, temporal lobe; Temporal lobectomy