Abstracts

Patients with temporal lobe epilepsy (TLE) usually present hippocampal sclerosis that can be detected by magnetic resonance imaging (MRI). Most of the resected hippocampi of patients with TLE resistant to pharmacological treatment are characterized by neuronal loss and abnormal mossy fiber sprouting in the inner molecular layer of the fascia dentata. The main goal of this work was to study neuron density and mossy fiber distribution in the hippocampi of TLE patients with different MRI volumetric hippocampal profiles., Using MRI hippocampal volumetry, patients were classified as: 1) normal volume (NV; n=8; hippocampal volume with at least 2.5cm³); 2) mild atrophy (MA; n=9; hippocampal volume between 2 and 2.5cm³); and 3) severe atrophy (SA; n=10; hippocampal volume with less than 2cm³). Corresponding hippocampal histological sections were stained with cresylecht violet or hematoxylin/eosin for hippocampal cell counts and neo-Timm histochemistry for mossy fiber detection. Histological controls were autopsy patients (n= 13; without antemortem clinical seizures or evidence of brain pathology on postmortem examination)., 1) Compared to autopsies, all three TLE groups showed loss of granular cells (NV: 44%; MA: 43%; SA: 48%) and CA1 (NV: 83%; MA: 69%; SA: 72%), CA2 (NV: 39%; MA: 39%; SA: 47%); CA3a (NV: 64%; MA: 70%; SA: 62%) and CA4 (NV: 55%; MA: 63%; SA: 64%) pyramidal cells, p[lt]0,001; 2) all TLE groups presented higher neo-Timm staining in the inner molecular layer of the fascia dentata than their autopsy controls (gray level: Control: 7,6 [plusmn] 4; NV: 72,6 [plusmn] 8; MA: 90,8 [plusmn] 10,8; SA: 95,5 [plusmn] 8; p[lt]0,001)., Atrophy profile observed on MRI does not necessarily reflect either cell loss intensity or axonal reorganization in patients with TLE., (Supported by BAP-FAMERP; FAPESP [ndash] CInAPCe Project # 05/56447-7; CNPq.)