Abstracts

Rationale: Hippocampal sclerosis (HS) is the most common finding underlying refractory temporal lobe epilepsy (RTLE). HS is characterized by severe neuronal cell loss in Cornu Ammonis (CA) of the hippocampus and is also associated with dentate gyrus (DG) abnormalities: neuronal cell loss and cytoarchitectural disorganization (dispersion and bilamination). Functional genomic analysis of CA3 explants surgically obtained from RTLE patients with febrile seizure (FS) as initial precipitant injury (IPI) or without febrile seizure (NFS) history showed that FS group constitutes a different phenotype (Bando et al, 2011). Moreover, texture analysis performed in high resolution MRI of ex-vivo hippocampi allows the differentiation between this two groups (Alegro et al, 2012). This work aimed to evaluate histopathological findings and clinical data related to previous functional genomic and 3T MRI texture analysis in patients with RTLE associated to HS in FS, NFS and sclerosis patterns groups. Methods: Resected sclerotic hippocampi were histologically processed for Nissl staining (n=39). HS pattern was classified according to Blümcke et al (2007). Semi-quantitative assessment was made for neuronal loss (graded from 0 to 4) and dispersion (0-3) of the granule cell layer (GCL) in the hippocampal body. Stereological cell counting using the software Stereo Investigator (MBF Bioscience, USA) was performed in the GCL and hylus in four sequential histological slices of the hippocampal body equivalent to a MRI slice (1 mm). 3T MRI texture analysis was performed in DG images. Only variables with p<0,05 were considered significant. This study has been approved by research ethics committee (251/05). Results: Neuronal loss in the GCL was correlated to clinical parameters gender (p=0,003) and epilepsy onset (p=0,02). Comparisons between patients with early (until the age of 12) and late (from the age of 13) epilepsy onset showed that neuronal loss is also statistically different between FS and NFS groups (p=0,01). Patients with early epilepsy onset showed a lower age of IPI occurrence (p=0,001). Glial number in the hilus were higher in patients with late epilepsy onset (p=0,01). Granule cell dispersion and glial cell count in the GCL were not statistically different between the referred groups p>