Epilepsy is a common neurological disease and may result from several pathological conditions. Approximately 30% of patients with chronic epilepsy are refractory to drugs, thus being candidates for surgery. In these cases, hippocampal sclerosis (HS) and focal cortical dysplasia (FCD) are the most frequent neuropathological findings. The main histological changes present in HS are segmental loss of pyramidal neurons and intense astrogliosis. In 2013, the International Epilepsy League (ILAE) proposed a neuropathological classification of HS in categories defined according to neuronal loss and astrocyte reaction. Focal cortical dysplasia (FCD) is a malformation of development and may present with a wide spectrum of morphological changes, comprising cortical and cytoarchitectural abnormalities in the underlying white matter. In 2011, the ILAE proposed a classification, in which the isolated types of FCD (I and II) are distinct from that associated with a major epileptogenic lesion (type III). Histopathological studies in long-term epilepsy specimens from patients submitted to surgery have shown changes in the WM, sometimes associated with neuroimaging investigations. However, only part of these studies sought to associate specific histopathological data of the glial cell population and the possible changes in neuroimaging in the same region. Brazilian studies on this topic are uncommon. In the present project, we will perform histological analysis in the WM of specimens from patients operated due to clinical hypothesis of HS and FCD, focusing on astrocytes and microglia. In addition, we will obtain neuroimaging data related to the WM in the same brain region submitted to surgery. Our aim is to investigate the association between histological and imaging morphological findings, relate them to clinical evolutionary data and contribute to the understanding of the pathophysiology underlying the changes identified in WM.
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