Diagnostic value of computerized EEG topographic analysis in epilepsy (preliminary data)

A computerized EEG topographic analysis (CETA) was carried out in 69 epileptics in order to evaluate the diagnostic value of such an investigation compared to that of the routine interictal EEG. The spectral frequency analysis of the bioelectrical activity in these patients was accomplished both by the fast Fourier transform and by the autoregression method. The obtained data were used for the spatial analysis of the electrical activity which was performed both by the interhemispheric coherence technique and by the color-coded topographic mapping in frequency bands. The data analysis showed that in 58 (84.1%) of the epileptics in whom routine EEG evidenced focal interictal bioelectrical abnormalities CETA also showed such abnormalities. However, CETA revealed focal abnormalities also in 8 (72.7%) out of the 11 epileptics in whom interictal EEG was interpreted as normal. The data analysis also showed that CETA was more efficient than EEG in the detection of focal abnormalities in the epilepsy with slow graphic elements, in the partial epilepsy, in the epilepsy with late onset and in the therapy-resistant epilepsy. The focal abnormalities evidenced by CETA were more expanded than those evidenced by routine EEG and the topographic maps indicated the focal involvement of a significant number of frequency bands. Considering the results, the authors make some appreciation regarding the diagnostic values of CETA in epilepsy.