ObjectiveTo investigate the lateralization of ictal scalp EEG in different times in focal epilepsy.Methods356 surface ictal EEG of 41 patients were reviewed retrospectively in focal epilepsy arising from the mesial frontal, lateralfrontal, mesialtemporal, neocorticaltemporal, insular lobes and posterior cortex from July, 2010 to at, 2016. Each ictal scalp EEG was subdivided into ten epoches (E1-E10), then the lateralization of every epoch was analyzed. Ten epochs EEG were merged into three timesas E1-E3, E4-E6 and E7-E10. The ratio of lateralization, mislateralization and non-lateralization of each timeEEG were studied. Ictal onset zone (IOZ) were precise localized by intracranial EEG. The results of epileptogenic zone corresponded with surgical outcomes as seizure free or decreased.Results62% seizures were lateralized by surface ictal EEG in all epilepsies. Lateralized ictal scalp EEG were seen in nearly 80% of seizures in all times in temporal lobe epilepsy (TLE). The highest lateralization of 89% occurred inE4-E6 andfalse lateralization up to 30% in E1-E3 in mesial temporal lobe epilepsy (MTLE), whereas 95% lateralized seizures emerged in E1-E3 in neocortical temporal lobe epilepsy (NTLE). Apparent non-lateralization in all times were higher than lateralization in frontal lobe epilepsy (FLE), especially in mesial frontal lobe epilepsy (MFLE). Lateralization in E1-E3 was only 24% higher than other times. In addition, False lateralization never occurred in all times in lateral frontal lobe epilepsy (LFLE). There were maximum of 83%lateralized seizures in E1-E3 in LFLE and 93% in E1-E3 in posterior cortex epilepsy (PCE). Seizures arising from insular lobe epilepsy (ILE) tendedto predict less lateralization in all times.ConclusionsIctal scalp EEG of E1-E3 are valuable in the lateralization in all epilepsies particularly in LFLE, NTLE and PCE. Lateralized E4-E6 and E7-10 are very useful in MTLE.
ObjectiveThe time relationship between seizure semiology and epileptic discharges during focal epileptic seizures is a crucial predictor for the localization of epileptogenic zone. Low voltage fast activities (LVFA), especially gamma band oscillations, are confirmed to play a central role in ictogenesis and semiology production. In the present study, we focus on the “electro-clinical correlation” between LVFA in agranulo-dysgranular insulo-cingulate cortices and the sign of “Chapeau de gendarme (CDG)” via detailed analysis of ictal video-stereoencephalography (video-SEEG) of focal epileptic seizures. MethodsWe retrospectively analyzed the ictal video-SEEG of the 7 cases in which CDG signs were presented in habitual seizures and intracerebral electrodes were co-implanted in agranulo-dysgranular insular and cingulate cortices. We calculate the latency of LVFA in each of cortical regions of interest, agranulo-dygranular insular cortex, agranulo-dysgranular cingulate cortex, and the latency of CDG signs via visual and spectral analysis of the ictal SEEG. Moreover, Pearson correlation analysis and linear regression were used to test the time relationship between gamma band oscillations in agranulo-dysgranular insulo-cingulate cortices and generation of CDG signs. ResultsThe co-activation of LVFA occurred in agranulo-dysgranular insulo-cingulate cortices always preceded the appearance of CDG sign in all of the 69 seizures. The LVFA were confirmed as gamma band oscillations via spectral analysis of SEEG. A linear relationship between the latencies of CDG signs and the latencies of co-activation of agranulo-dysgranular insulo-cingulate cortices in gamma band was furth confirmed by Pearson correlation analysis and linear regression. ConclusionsThere is a causal relationship between the involvement of agranulo-dysgranular insulo-cingulate cortices and the generation of CDG sign, and thus the CDG sign could be view as semiological marker of activation of emotional insulo-cingulate cortex in focal epilepsy.