Abstracts

Rationale: Structural changes in temporal lobe epilepsy patients with a MR diagnosis of mesial temporal sclerosis (MTS) go beyond that level. Magnetic Resonance Diffusion Tensor Imaging (MR-DTI) permits to evaluate those changes and quantify them. Methods: Twenty patients with a MR diagnosis of MTS and twenty healthy controls were included in this study. All the patients had a refractory epilepsy and were operated on, performing anterior temporal lobectomy with amygdalohippocampectomy in all of them. Patients and controls underwent a MR study on a Siemens 3 Tesla system. The study protocol included DTI-MR images and Volume-one computational analysis. DTI study included fractional anisotropy (FA) and apparent diffusion coefficient (ADC) evaluation of hippocampus, parahippocampus, temporal pole, uncus and uncinate fasciculus. These data were correlated with neuropathological finding obtained in hippocampus and temporal lobe after epilepsy surgery. Statistical test used for this analysis was a Student t-test. Results: ADC significative changes (p<0.001) in the ipsilateral and affected hippocampus with respect to healthy controls and with respect to contralateral hippocampus was observed. Moreover, a FA reduction (p<0.004) and ADC changes (p<0.001) of ipsilateral parahippocampus in MTS patients with respect to healthy controls and with respect to contralateral parahippocampus was observed. The interpretation of parahippocampus changes was a decrease in neuronal cellularity (ADC) and connectivity (FA) in this anatomical structure, that was correlated with neuropathological findings. A significative FA reduction in (p<0.05) and a significative ADC increase (p<0.001) was observed in the ipsilateral temporal pole of MTS patients with respect to healthy controls and contralateral temporal pole. The ipsilateral uncinate fasciculus (UF) in MTS patients showed a FA decrease (p<0.001) and ADC increase (p<0.001) with respect to healthy controls an contralateral UF. Ipsilateral uncus showed significative ADC changes (p<0.001) with respect to healthy controls and contralateral uncus. Changes in fronto-temporal connectivity through UF and a tract reduction can explain these changes. Conclusions: MR-DTI findings in MTS patients confirm neuropathological results and support the extention of surgical resection to enthorrinal pole and parahippocampus. UF changes permit to evaluate the level of lesional changes.