Abstracts

Rationale: To evaluate the diagnostic accuracy of individual presurgical modalities, compared with intracranial EEG as a gold standard, and to study a role of multimodal approach associated with surgical outcome in nonlesional pediatric epilepsy. Methods: Fourteen children (3-18 years) with nonlesional intractable partial epilepsy were studied. Clinical characteristics, surgical outcome, localizing features on presurgical diagnostic tests including SISCOM, SPM analysis of 18F-FDG-PET, MEG, and intracranial EEG were reviewed. Localization of individual test was determined by visual inspection of sub-lobar location. Comparison of localization between each test and intracranial EEG led to concordance scores as follows: +2= sublobar concordance; +1= lobar concordance; 0= hemispheric concordance; -1= discordance or nonlocalization. Total concordance score in each patient was measured by the summation of concordance scores for all three tests. Results: 1) Eight (57%) out of 14 patients were seizure free at least 6 months follow up post-operatively. One (7%) presented with rare seizures (Engel class II) and 5 (36%) had persistent seizures (class III and IV). 2) Comparing concordance rate of individual test with intracranial EEG, both MEG and SISCOM showed concordance values greater than SPM-PET: the sum of concordance score was 18 for MEG, 16 for SISCOM, and 4 for SPM-PET respectively. 3) Total concordance score was greater for seizure-free group compared with non seizure-free group (class II, III, IV): the average of total concordance scores was 3.4 in seizure-free group, while the score was 2.0 in non seizure-free group (p-value < 0.05, Wilcoxon rank sum test). Conclusions: Our data suggest that MEG and SISCOM are better localization tools for non-lesional pediatric epilepsy. Seizure-free outcome was clearly associated with higher concordance score of multi-modal tests. Multi-modaility approach may allow an increased percentage of patients without MRI abnormality to be considered for surgical treatment and improve their overall surgical outcome. Further prospective study may be required to validate our study.