Abstracts

Independent component analysis (ICA) is a system that differentiates components of complex signals. One of its capabilities is to study the epileptiform discharges to demonstrate similar or different origin of its components. The goal of this study was to discover how ICA analyse the discharges in the benign centrospikes, to understand better this kind of idiopathic epilepsy. We analysed 15 discharges of 3 patients with benign centrotemporal epilepsy. Their morphology was sharp wave, spike or spike-and-wave. The samples were recorded digitally with a 32-channels Lamont amplifiers and Harmonie 5.2b program. ICA was applied using the JADE algorithm implemented in a Matlab platform. The components were identified visually. The suspected components were selected and the EEG of these components by itself and together were reconstructed. The topography in each component of the discharge was compared with the original using the BESA program in the same period. The spikes and waves were located in different components. Spikes were separated in one (n=10), two (n= 4) or three (n=1) components, with delay between their maximums of 5-10 ms. The waves were isolated in other one or two components. Their topography was centrotemporal, very similar but not identical. The lateralization of each component was variable between components of the same spike, and it could be right, left or bilateral. Each component of the spike fit very well with the EEG in the correspondent time. The topography of the components from different spikes of the same patient varied slightly in the localisation. ICA differentiates several components with temporal evolution in the epileptiform discharges in centrotemporal epilepsy. In most of the discharges, the spike and the wave had different components suggesting different origin. Their topography was centrotemporal, similar but variable in the lateralization and localisation. In each patient the way of analysis of the discharge was very similar but not identical.