Abstracts

Rationale: Focal cortical dysplasia (FCD) causes intractable epilepsy. We elucidated (1) spatial congruence of distribution of MEG spike source (MEGSS) and FCD, (2) whether MEGSS could show accurate localization of FCD at the bottom of sulcus (BOS). Methods: We analyzed 14 patients who underwent scalp video EEG, 3T MRI, MEG, intracranial video EEG, and surgery for intractable epilepsy with histopathological confirmation of FCD typeⅡ. We evaluated concordance between clustering of MEGSS and FCD as fully concordant, partially concordant and discordant. We subdivided partially concordant as significant partially concordant when clustering of MEGSS overlapped FCD lesion more than 50%. We evaluated the distribution of MEGSS, surgical resection area and seizure outcome. Results: 14 patients' age ranged 3-17y.o (mean 9.5 y.o). Nine patients had FCD at convexity and 5 patients had FCD at BOS. In 9 patients with FCD at convexity, 2 patients had clustering of MEGSS fully concordant with FCD (2583, 10595mm³). Six patients had clustering of MEGSS partially concordant with FCD. Among these patients, five patients had MEGSS cluster significantly partially concordant with FCD (3670, 7398, 26210, 26573, 57331mm³), and one patient had MEGSS cluster partially concordant with FCD (2375mm3). The remain one patient had only scattering of MEGSS (2500mm³). In 5 patients with FCD at BOS, 3 patients had clustering of MEGSS partially concordant with FCD (2255, 3351, 4707mm³). Other 2 patients had clustering of MEGSS discordant from FCD (1632, 2669mm³). We underwent resective surgery following intracranial video EEG in all patients. FCD lesions were completely resected in all patients except one patient with FCD at convexity. Clustering of MEGSS area were completely resected in 4 of 9 patients with FCD at convexity and in 3 of 5 patients with FCD at BOS. After resective surgery, 6 of 8 patients became seizure free (ILAE class 1) and 2 patients were classified as ILAE class 4 in patients with FCD at convexity. Three of 5 patients became seizure free (ILAE class 1) and 2 patients were classified as ILAE class 4 in patients with FCD at BOS. Conclusions: Spatial congruence between clustering of MEGSS and FCD was more concordant in FCD at convexity than at BOSs. FCD at convexity required more than 2583mm³ in volume to demonstrate more than partially concordant clustering of MEGSS.