Expressão da sintase neuronal do óxido nítrico na displasia cortical focal tipo Taylor

Abstract

Focal cortical dysplasias (FCDs) are characterized by a focal disorganization of the normal structure of the cerebral cortex, which has been ascribed to malformations of cortical development (MCD). Focal cortical dysplasia type IIb or Taylor type, studied here, is characterized by the loss of cortical organization, dysmorphic neurons (DNs) and balloon cells (BCs). Patients with the disturbance presented drug-resistant epilepsy that underwent surgical resection of the epileptogenic region for the treatment of epilepsy. Epileptogenicity in FCD has usually been ascribed to a disturbance(s) of the excitation-inhibition balance. The properties of nitric oxide (NO) make it a putative candidate to participate in excitationinhibition balance. NO is a hydrophobic, freely diffusible radical gas that can permeate cell membranes. Patients evaluation included a detailed history and neurologic examination, interictal-ictal scalp EEG, interictal/ictal video-EEG monitoring, an extensive neuropsychological test battery and intra-operative cortical recording. The resected cortexes were studied using routine stains (H&E, cresyl violet and silver impregnation by the Bielschowsky method. Neuronal NOS (nNOS), pan-neuronal neurofilament marker (SMI311) and glial fibrillary acidic protein (GFAP) expressions were detected using specific antibodies in immunohistochemistry. We studied 23 patients presenting FCD IIb. The epileptogenic lesions in FCD patients were widely distributed over diverse cortical regions. Cortical dysplasia, BCs and DNs were found in all twenty-three patients. Hypertrophic, and dysmorphic neurons, and balloon cells expressed nNOS with variable intensity. Bipolar, multipolar or unnamed interneurons were found to stain for nNOS. Long varicose processes were observed in all FCD IIb cases. In some cases there was a variable intensity, nuclear expression of nNOS, apparently in most neuron types. Staining of both cytoplasm and nucleus of BCs was variable. The expression nNOS in different cell types and cellular structures of neocortex were detected in patient with focal cortical dysplasia IIb.