Divergent Propagation Networks Define Two Pathophysiologically Distinct Electroclinical Phenotypes in Mesial Temporal Lobe Epilepsy

Background and Purpose Temporal dissociation between electrographic and clinical seizure onset in mesial temporal lobe epilepsy (MTLE) implies network heterogeneity.We hypothesized that MTLE consists of distinct electroclinical phenotypes defined by divergent seizure propagation dynamics. MethodsWe retrospectively analyzed 167 seizures from 13 patients with drug-resistant MTLE who achieved Engel Class I surgical outcomes.Based on the predominant relationship between scalp electroencephalography (EEG) and clinical onset, patients were classified as EEG-first (n=7) or Clinical-first (n=6).Seizure onset patterns, propagation pathways, and temporal dynamics were assessed using scalp and stereoelectroencephalography (SEEG). ResultsThe cohort included 83 scalp and 84 SEEG seizures.By definition, onset order differed: in EEG-first seizures, scalp changes preceded clinical signs in 70.5%, whereas the reverse occurred in 65.8% of Clinical-first seizures (p