Abstracts

RATIONALE: According to the coherence study of interactions between medial/limbic and lateral/neocortical regions, we have recently proposed a classification of temporal lobe epilepsies seizures (TLES) in four subtypes of epileptogenic networks: medial (M), medial-lateral (ML), lateral-medial (LM), Lateral (L) TLES. In this study based on nonlinear analysis, we have more precisely analyzed the interactions (degree and direction) between medial and neocortical areas in TLES. METHODS: 20 patients with drug-resistant TLEs that underwent SEEG recording were studied. According to Pijn et al (1993) we used a non linear correlation coefficient (h2) as a measure of the degree and the direction of coupling on SEEG signal pairs. Patients with pure lateral TLEs were not studied. We analyzed the functional coupling between three regions of temporal lobe: the anterior T2 neocortex (NCx), the amygdala (A) and the anterior hippocampus (H). RESULTS: a/ 12 patients had "medial" network, characterized by the absence of significant interaction between medial (A,H) and lateral (NCx) structures at the onset of seizure.11/12 patients had high h2 values between A and H. The "leader"structure was in 6 cases the amygdala, in 4 cases the hippocampus. In 1 case, there was a bi-directional coupling. In some cases, the networks also involved the limbic part of the temporal pole and entorhinal cortex b/ 4 patients had "medial-lateral" network characterized by initial high h2 values between medial and lateral structures. In this group, the NCx appeared to be driven by medial structures (A or A and H) at the onset of seizure. c/ 4 patients had "lateral-medial " network in which initial high h2 values were found between medial and lateral structures. In this group, the NCx has an initial leading role while medial structures appear to be driven. CONCLUSIONS: These results demonstrate the existence of several generic and organized networks involved during TLE seizures.