Abstracts

RATIONALE: To compare the scalp and the invasive cortical EEG findings of frontal lobe epilepsy (FLE) and to investigate the anatomical location of seizure origin in three different semiological groups METHODS: Total 361 seizures in 78 FLE patients were reviewed and epilepsy surgery with invasive study was done in 36 patients. They were classified to two groups by the invasive ictal localization: (1) pure frontal group, in which all of the seizures were originated from frontal lobe only, and (2) plus frontal one with seizures from frontal and extrafrontal origins. RESULTS: Compared to the invasive results, scalp interictal and ictal EEGs showed 67% (24/36) and 70% (25/36) of concordance rates, respectively. The distributions of interictal and ictal discharges were illustrated in the schematic brain maps. In 28 patients of pure frontal group, the ictal EEG localization was analyzed in three different semiological groups: (1) supplementary motor (SMA) seizures, (2) focal motor seizures, and (3) complex partial seizures (CPS). The final localization was quite variable in each group, but most commonly mesial + dorsolateral frontal regions (5/11, 45.5%) in 11 SMA seizures, dorsolateral frontal (5/12, 41.7%) in focal motor seizures, and dorsolateral + orbitofrontal regions (3/13, 23.1%) in CPS group. The invasive interictal and ictal EEGs were concordant in 89.3% (25/28). CONCLUSIONS: Although the EEG features of FLE were so complicated probably due to the extensive anatomical distribution with complex anatomical structures of frontal lobe, scalp EEG could predict the location of seizure discharges in 70%. Semiological subgroups of FLE showed various anatomical distribution of ictal onset zones, which suggested that symptomatogenic zones could be away from where the seizures originated.