Spatiotemporal imaging of ‘generalized' seizure activity using MEG

Abstract

Event Abstract Back to Event Spatiotemporal imaging of ‘generalized' seizure activity using MEG Pauly Ossenblok1*, Bert Kornips1, Hans Carpay2, Paul Boon1 and Gilles Van Luijtelaar3 1 Epilepsy Centre Kempenhaeghe, Netherlands 2 Tergooi Hospitals , Netherlands 3 Donders Center for Cognition, Netherlands Studies in the WAG/Rij rat [1] challenge the theory of primary generalized absence epilepsy by showing a crucial role for the cortex in generating the spike-and-wave discharges (SWDs). Association analysis of MEG signals recorded for children with absence epilepsy also demonstrated a focal onset region, followed by a recurrent pattern of regional activity during the spikes alternated by generalized activity during the slow-wave of the SWDs [2]. More recent findings of our study raised the question whether clinically distinct types of absence epilepsy differ by origin, while sharing a common corticothalamic network during the evolvement of the SWDs. The population studied (n=20; 6 – 14 years of age) ranges from patients with typical childhood absence epilepsy, who can be treated quite successfully with anti-epileptics, to more complex atypical forms and children who had absences and complex partial clinical features. For each of the seizures of these children the non-linear association analysis was performed, yielding both the dynamics of the SWDs and the regional distribution of the spikes, while the cortical origin of the SWDs was studied using advanced source analysis. The association analysis results of the SWDs indicated the involvement of mesiofrontal cortex and the bilateral frontal and temporoparietal regions during the spikes of the SWDs for each of the patients studied. However, the initial onset of the SWDs of the patients differing with regard to their clinical features may reflect either left or right frontal or temporoparietal regional activity or in case of complex partial semiology regional onset activity e.g. at the temporal lobe, a result which was in concordance with the dipole scan (MUSIC). If cortical structures activated before generalization can be identified for distinct subpopulations of absence epilepsy patients, this will change not only the concept of epilepsy, but also will improve the differential diagnosis of childhood absence epilepsy and may open new ways for treatment.