Abstracts

Rationale: To study, in patients with frontal lobe epilepsy, the relationship between interictal epileptiform discharges and the microstructural integrity of the anterior aspects of the corpus callosum (CC). Specifically, we tested whether the interhemispheric propagation of frontal lobe discharges is correlated with changes in the functional integrity of the genu of the CC. Methods: We analyzed, retrospectively, data from 17 right-handed patients diagnosed with refractory frontal lobe epilepsy that underwent MEG and MRI assessments, including Diffusion Tensor Imaging (DTI) sequence, as part of their presurgical evaluation. Three of the 17 cases were excluded: two due to inconclusive MEG results and one due to poor quality of DTI sequences. During the review of the MEG recordings, interictal discharge sources localized in the frontal lobe were further analyzed to extract the patterns of propagation (intrahemispheric or interhemispheric).Values of regional fractional anisotropy (FA) of the genu of the CC were extracted from DTI sequences (mid-sagittal slice) following subdivisions into seven regions, using the "Witelson" technique. Results: In the 14 cases analyzed, the patterns of interictal MEG activity was classified in two sets: The first included 6 cases showing intrahemispheric (intralobar or interlobar) and the second 8 cases showing interhemispheric propagation. Patients with interhemispheric patterns of spike propagation showed reduced FA values at the genu of the CC as compared to those with intrahemispheric propagation (p < 0.05). Surgical outcome was available in 11 patients with no significant difference between the two groups. Conclusions: Microstructural white matter alterations occur in the genu of the corpus callosum in patients with frontal epilepsy showing interhemispheric patterns of propagation of epileptic activity. The significance of this finding and its value in predicting surgical outcome should be further investigated.