EEG-related functional MRI in benign childhood epilepsy with centrotemporal spikes

The localization of epileptic foci is an important issue in children with extratemporal epilepsies. However, the value of noninvasive methods such as the EEG-assisted functional magnetic resonance imaging (fMRI) has not been sufficiently investigated in children. As a model of extratemporal epilepsies, we studied 7 patients aged 5 to 12 (median 10) years with benign childhood epilepsy and centrotemporal (rolandic) spikes. Interictal spikes were recorded during the fMRI acquisition on a MR-compatible battery-powered digital EEG system with 16 channels. The fMRI sequences were correlated off-line with the EEG spikes and analyzed with the software Statistical Parametrical Mapping SPM99. The fMRI results demonstrated the spike-related activation in the perisylvian central region in three patients; we could not demonstrate fMRI activation despite active spiking in 2 patients, and 2 patients did not produce sufficient spikes for fMRI analysis. We currently consider the spike-related fMRI as a research tool that localizes epileptic activity in selected patients. Further improvements of the technique are necessary to allow a clinical application of this method.