Navegando por Assunto "Epilepsy"

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Acesso aberto (Open Access)
Classificação de eletroencefalogramas epiléticos em estado de repouso com aplicação de classificadores lineares e um atributo derivado da densidade espectral de potência
(Universidade Federal do Pará, 2019-12-04) FIEL, José de Santana; PEREIRA JÚNIOR, Antonio; http://lattes.cnpq.br/3239362677711162
Millions of Brazilians are affected with epilepsy and the access to early diagnosis is crucial for their adequate treatment. However, epilepsy diagnosis depends on the evaluation of longduration electroencephalographic (EEG) recordings performed by trained professionals, turning it in a time-consuming process which is not readily available for many patients. Thus, the present work proposes a methodology for automatic EEG classification of epileptic subjects which uses short-duration EEG recordings obtained with the patient at rest. The system is based on machine learning algorithms that use an attribute extracted from the power spectral density of EEG signals. This attribute is an estimate of functional connectivity between EEG channel pairs and is called debiased weighted phase-lag index. The classification algorithms were linear discriminant analysis (LDA) and support vector machines (SVM). EEG signs were acquired during the interictal state, i.e., between seizures and had no epileptiform activity. Recordings of 11 epileptic patients and 7 healthy subjects were used to evaluate the method’s performance. Both algorithms reached their maximum classification performances, 100 % accuracy and area under the receiver operating characteristic (AUROC) curve, when a feature vector with 190 attributes was used as input. The results show the efficacy of the proposed system, given its high classification performance.
Acesso aberto (Open Access)
Relação entre neurogênese hipocampal e história clínica de pacientes adultos portadores de epilepsia refratária do lobo temporal.
(Universidade Federal do Pará, 2018-09-13) GAMA, Jessica Silva; SOUSA, Regina Célia Gomes de; http://lattes.cnpq.br/5576436464955236; LIMA, Silene Maria Araújo de; http://lattes.cnpq.br/8961057812067156
Epilepsy is a neurological disorder characterized by the permanent predisposition of the brain to generate epileptic seizures, which affects about 1% of the world population. In Brazil, the disease can reach 2% to 4% of the population. Most patients have a good prognosis for drug treatment, however 30% of patients are refractory to treatment. Among the epilepsies that do not present a good prognosis is the Temporal Lobe Epilepsy (ELT). ELT is characterized morphologically by a selective loss of hippocampal neurons, concomitantly with increased hippocampal neurogenesis. It is believed that this exacerbated neurogenesis contributes to epileptogenesis (onset of epilepsy); however, the role of this increased neurogenesis in patients with TLE remains unknown. We used hippocampus from patients with epilepsy, who underwent a surgical procedure in which unilateral hippocampal resection was performed. From the analysis of the same, a possible relationship between neurogenic patterns and the evolution of the disease was investigated. Interviews with patients who underwent surgery demonstrated that the triggering event (precipitant) of epilepsy occurred in the first years of life of the patients. In addition, they were high intensity events, and also presented a high frequency of epileptic seizures and drug refractoriness. Immunohistochemical analysis of hippocampi showed equivalently that there was a perceptible dispersion of the granule cell layer, indicating a possible ectopic migration in labeling for neuroblasts (immature neurons), which are generated in neurogenesis. The results obtained in this work are pioneer, given that they are based on both clinical and histopathological findings, and the relationship between hippocampal neurogenesis and clinical history proposes a new research vision. These findings may also help in a new perspective of differential treatment in temporal lobe epilepsies.