Abstracts

Rationale: The most common cause of drug-resistant epilepsy is MTLE secondary to hyppocampal sclerosis (HS). In mesial temporal lobe epilepsy (MTLE) the postoperative seizure outcome, in terms of seizure freedom, is about 80%; however up to 20% of patients continue having seizures after surgery. In order to delineate better the epileptogenic zone in these patients Diffusion Tensor Imaging (DTI) has been used as part of the non-invasive preoperative evaluation of patients with MTLE. This technique has the ability to determine changes in cerebral cortico-subcortical microscopic structure. The aim of this study was to determine whether DTI could be able to determine the precise location of the epileptogenic lesion in patients with MTLE non-invasively. Methods: We selected ten patientes with MTLE and HS (5 left, 5 right) who underwent a comprehemsive presurgical evaluation, including FDG-PET. Then each patient in this group was compared to a control group comprised of 30 non-epileptic healthy subjects. For these analysis we used a two samples t-test using SPM8. Results: There was an increase in mean diffusivity (MD) over the ipsilateral mesial temporal region as well as over the thalamus, the caudate nucleus, and the cingulate and frontal region in all patients. There was also a decrease in fractional anisotropy (FA) over of the ipsilateral insular region and both basal frontal regions, involving the main propagation pathways known in MTLE. There was also a good agreement between the FDG-PET hypometabolism and the increase in MD. Conclusions: In conclusion, DTI might be a useful technique for the noninvasive presurgical evaluation in patients with MTLE. In most cases it indicates the location of the epileptogenic lesion, as well as other areas that could be primarily involved in seizure generation and propagation.