Jeana Torres Corso Duarte, Maria Teresa Fernandes Castilho Garcia, Larissa Botelho Gaça, Ricardo Silva Centeno, Anaclara Prada Jardim, Henrique Carrete, Esper A. Cavalheiro, Luciana Rodrigues De Marchi, Mirian Salvadori Bittar Guaranha, Andrea Parolin Jackowski, Sandra Mara Comper, Elza Márcia Targas Yacubian, Gabriel Barbosa Sandim, Idaiane Batista de Assunção-Leme, and Carmen Lucia Penteado Lancellotti
Purpose To evaluate if the duration of epilepsy influences MRI volumes of the hippocampus, amygdala, parahippocampal gyrus, entorhinal cortex and temporal pole of both hemispheres and epileptogenic hippocampus neuronal cell density and dentate gyrus granular cells distribution in patients with refractory mesial temporal lobe epilepsy due to hippocampal sclerosis (MTLE/HS). Methods Seventy-seven patients with refractory MTLE/HS submitted to surgery were included. Histopathological analysis included: (1) quantitative: hippocampal subfields and total estimated hippocampal cell density (HCD), thickness of the dentate gyrus – normal, thinning or dispersion; (2) qualitative: type of HS and granule cells pathology in the dentate gyrus (normal, neuronal cell loss, dispersion and bilamination). Automated MRI-derived measurements from bilateral temporal structures (hippocampus, amygdala, parahippocampal gyrus, temporal pole, entorhinal cortex) were obtained for 58 subjects. Histopathological and imaging findings were compared with data from specimens obtained in autopsies of age-matched individuals and living controls, respectively, and the data were adjusted for the age at epilepsy onset and the frequency of focal impaired awareness seizures/month. Results Forty-two (54.5%) patients presented right HS. The greater the duration of epilepsy, the smaller the total estimated HCD (p = 0.025; r = −0.259). Patients with a normal distribution of the granular cells had a shorter epilepsy duration than those with dispersion (p = 0.018) or thinning (p = 0.031). A reduced ipsilateral hippocampal volume (r = −0.551, p = 0.017) and a smaller hippocampal asymmetry index (r = −0.414, p = 0.002) were correlated to a longer epilepsy duration. The estimated HCD was correlated to the volume of the ipsilateral hippocampus (r = 0.420, p = 0.001). Conclusion Our study showed an increasing atrophy of the ipsilateral hippocampus in patients with a longer epilepsy duration. Our data suggest that this reduction in hippocampal volume is related to neuronal loss. Besides that, we also showed an increased probability of exhibiting an abnormal distribution of the granular cells in the dentate gyrus in patients with longer epilepsy duration.