Abstracts

Rationale: To combine Magnetoencephalography (MEG) and Diffusion Tensor Imaging (DTI) and explore the association between functional and structural connectivity supporting epileptiform activity in frontotemporal epilepsy. Specifically, we tested whether the presence of frequent focal epileptiform activity affecting the frontotemporal structures is accompanied by changes in the structural integrity of the uncinate fasciculus (UF).Methods: In the context of presurgical evaluation, 7 right-handed epileptic patients with history of refractory epilepsy underwent MEG and MRI assessments (including DTI sequence). In 3 cases MEG localization of interictal activity (i.e., epileptiform discharges) showed onset and propagation of activity within the anterior temporal and inferior frontal lobe structures. In 4 patients, the interictal activity was localized in distant areas including perirolandic, parietal and/or occipital regions. These localizations were confirmed as being part of the ictal onset zones following extensive vEEG monitoring (7 out of 7), invasive recordings (4 of 7) and successful surgical outcome (4 out of 7, with 3 cases pending surgery). Values of fractional anisotropy (FA) were derived from DTI sequences following reconstruction of the uncinate fasciculus (UF) ipsilateral and contralateral to affected hemisphere (Figure 1). Results: In all the patients with focal frontotemporal discharges, FA values were lower for the UF in the affected hemisphere (see Figure 2). For the 4 cases with interictal activity localized elsewhere (not in frontotemporal regions) there were no evident asymmetries in FA values of the UF. A description of the individual results, on a case by case basis, is presented.Conclusions: Analysis of MEG spikes can help to characterize the course of frontotemporal spikes (Tanakla et al., 2009) and in this group of patients seems to coincide with distorted diffusivity in the UF. The individual results suggest that the structural integrity of the UF is compromised in presence of frontotemporal discharges.