A topographical display of epileptiform transients based on a statistical approach

A method for the analysis of topographical relations of EEG epileptiform transients based on a statistical approach is described. The degree of time association of those transients recorded in pairs of derivations, or in 3 (triads), 4 (tetrads) or more derivations is estimated, using the chi2 statistic. Pairs of derivations which are found to be significantly associated are tabulated. This information is also graphically displayed on a computer drawing of the head (10-20 system). The same is done for triads, tetrads or higher order associations. The number of phase reversals between epileptiform transients found in significantly associated pairs of derivations is also computed. The resulting spatial displays enable a visualization of the location of the dominant epileptogenic area and of the spread of epileptiform activity over the head.