Electrical source analysis by brain mapping techniques.

Brain EEG mapping techniques are employed in our department as a preliminary device for the selection of patient tributaries for more complex neurophysiological techniques: EEG combined with video-filming, foramen ovale electrodes, depth and subdural electrodes etc. Different methods of brain EEG mapping may be employed for the localization of the origin of epileptic discharges: power maps based on a FFT method; power maps based on instantaneous EEG amplitude; and in the last few years, new dipole programs working with the dipole localization method, the so-called 'inverse solution', that indicates the existence of one or more dipoles as sources of discharges, and their localization in a coordinate axis oriented in the three space directions. Brain EEG mapping has the advantage of low cost, but its main inconvenience is the relatively low level of accuracy in the localization of the sources. Neuromagnetic techniques give the best level of accuracy in source localization, but their cost is very high. The final considerations would be how much neuromagnetic techniques improve the results obtained by brain mapping techniques, and the specific areas where these techniques should be assigned.