O28 Advanced dynamic statistical parametric mapping (ADSPM) for focal cortical dysplasia at bottom of sulcus

Abstract

Objective To investigate whether our new technique of AdSPM for MEG could demonstrate epileptogenic focal cortical dysplasia at bottom of sulcus (FCDB). Methods We analyzed 15 children (9 males; mean, 8.8 years) with FCDB, 3T MRI, scalp video EEG, and MEG. We compared spatial congruence between (1) FCDB and MEG cluster of single moving dipoles (SMD), (2) FCDB and spike volume in AdSPM. In SMD, we defined “Hit” when cluster overlapped FCDB. We defined “No hit” when cluster was remote from FCDB or when there was only scatter. In AdSPM, we analyzed each 100 ms segment around MEG spike dipole. We summated dSPM to estimate the source activity. The area with highest threshold was defined as spike volume location. We defined “Hit” when spike volume located in FCDB. Results 12 children were diagnosed as FCD typeII in surgical specimen and the other 3 children were diagnosed as FCD type II on MRI. AdSPM hit FCDB in 12 of 15 children (80%) whereas MEG cluster hit 6 (33%). The detection ratio of FCDB was significantly higher in AdSPM than that of SMD ( p = 0.03). Spike volume location was concordant within seizure onset zone in 9 (81%) of 11 children who underwent IVEEG. All 11 children with respective surgery and available follow-up achieved seizure freedom. Ten (90%) of the 11 children had spike volume in the resection area. Discussion AdSPM estimates spike source of epileptogenic FCDB. Conclusion AdSPM hit epileptogenic FCDB. Significance AdSPM noninvasively and neurophysiologically demonstrates epileptogenic FCDB.