Acoplamento neurovascular e neuroimagem funcional em epilepsia

INTRODUCTION: The neural regulation of the microcirculation is done by the functional neurovascular unit that is composed of vascular, astroglial and neuronal cells. The neurovascular unit represents the interface between the Central Nervous System and the Vascular System. OBJECTIVE: This paper reviews the literature on functional neuroimaging with a particular focus on the mechanisms of the neurovascular coupling. CONCLUSIONS: Functional neuroimaging techniques as functional MRI, SPECT and PET distinguish metabolic and physiological processes underlying normal and abnormal events, based on neurovascular coupling. Although these techniques still have limitations in temporal and spatial resolution, they have considerably reduced the need for intracranial electrodes or invasive functional tests in the presurgical evaluation for intractable epilepsy. Recently, new techniques as optical approaches (measurement of intrinsic optical signals and near infrared spectroscopy) have increased both temporal and spatial resolutions. The use of such techniques in animal models has yielded experimental evidence for a neurovascular coupling in normal and epileptic conditions.INTRODUÇÃO: A regulação da microcirculação cerebral é realizada pela unidade neurovascular, que é composta por vasos sangüíneos, células astrogliais e neuronais. A unidade neurovascular representa a interface funcional entre o Sistema Nervoso Central e o sistema vascular. OBJETIVO: Este trabalho revisa a literatura sobre técnicas de neuroimagem funcional com especial enfoque nos mecanismos do acoplamento neurovascular. CONCLUSÃO: Técnicas de neuroimagem como a Ressonância Magnética funcional, SPECT e PET baseiam-se no acoplamento neurovascular para explorarem os processos metabólicos e fisiológicos subjacentes a eventos cerebrais normais e anormais. Embora estas técnicas apresentem limitações de resolução temporal e espacial, sua aplicabilidade em epilepsia tem reduzido consideravelmente a necessidade de eletrodos intracranianos e de outros métodos funcionais invasivos na avaliação pré-cirúrgica de pacientes com epilepsia intratável. Recentemente, novos procedimentos ópticos (mensuração do sinal intrínseco óptico e espectroscopia por raio infravermelho) que possuem excelente resolução espacial e temporal têm fornecido evidências experimentais do acoplamento neurovascular no cérebro normal e epiléptico

Ativação variável da ressonância magnética funcional com duas tarefas diferentes em um paciente com retardo mental

Functional MRI produces a more accurate localization of the language areas for epilepsy surgery purpose, but requires the patient cooperation. We report a 34 years-old woman with mental retardation who underwent two different verbal fluency tasks, category and word naming. We found a strong activation of the Broca’s area in the most difficult task. We suggest that a multi-task fMRI study could be successful in patients with cognitive delay.A ressonância magnética funcional permite uma localização acurada da área da linguagem para fins de cirurgia de epilepsia, mas requer a colaboração do paciente na execução da tarefa proposta, o que pode limitar a sua utilização em pacientes com retardo mental. Nós apresentamos o caso de uma mulher com 34 anos de idade, com retardo mental, que foi submetida a duas tarefas distintas de geração silenciosa de palavras, por categoria e letras. Encontramos forte ativação da área de Broca na tarefa mais complexa. Sugerimos que um estudo com múltiplas tarefas pode ser útil em pacientes com retardo mental

Encefalite de Rasmussen: avaliação de resultados depois da cirurgia

BACKGROUND AND PURPOSE: Rasmussen Encephalitis (RE) is characterized by intractable epilepsy, progressive hemiparesis and unilateral hemispheric atrophy. The progression of the symptoms usually occurs within months to few years. Antiepileptic drugs are usually not effective to control disease progression and epilepsy surgery in the form of hemispheric disconnection has been considered the treatment of choice. This work describes the clinical and electrographic analyses, as well as the post-operative evolution of patients with RE. PATIENTS AND METHODS: This work includes all the patients with RE evaluated from January 1995 to January 2008 by the Ribeirão Preto Epilepsy Surgery Program (CIREP) considering demographic data, interictal and ictal electroencephalographic (EEG) findings; anatomo-pathological findings and clinical outcome. RESULTS: Twenty-five patients were evaluated, thirteen were female. Mean age of epilepsy onset was 4.4±2.0 years. There were no differences between patients with slow and fast evolution with respect to age of epilepsy onset (p=0.79), age at surgery (p=0.24), duration of epilepsy (0.06), and follow-up (p=0.40). There were no correlations between the presence of bilateral EEG abnormalities or the absence of spikes and post-operative seizure outcome (p=0.06). Twenty-three patients underwent surgery. The mean follow-up was 75.3 months. Eleven patients had total seizure control. Twelve individuals persisted with seizures consisting of mild facial jerks (6 patients), occasional hemigeneralized tonic-clonic seizures (3 patients), and frequent tonic-clonic seizures (3 patients). Mental and language impairment was observed in 15 and 12 patients, after surgery, respectively. CONCLUSIONS: This retrospective study reported the clinical and electrographic analysis, as well as the evolution of 23 patients with RE. Fourteen patients achieved satisfactory seizure control, three patients had partial response to surgery, and five patients had maintenance of the pre-operative condition. All patients with left side involvement presented with some language and cognitive disturbance.INTRODUÇÃO E OBJETIVOS: A Encefalite de Rasmussen (ER) é caracterizada por epilepsia intratável, hemiparesia progressiva e atrofia hemisférica unilateral. A progressão dos sintomas geralmente ocorre em meses ou poucos anos. As drogas antiepilépticas são usualmente ineficazes no controle da progressão da doença e o tratamento cirúrgico, com desconexão hemisférica tem sido considerado o tratamento de escolha. Neste trabalho descreveremos os achados clínicos e eletrográficos, assim como a evolução pós-operatória de pacientes com ER. PACIENTES E MÉTODOS: foram incluídos todos os pacientes com ER avaliados no período de janeiro de 1995 a janeiro de 2008, no Centro de Cirurgia de Epilepsia de Ribeirão Preto (CIREP), sendo considerados os dados demográficos, os achados do eletrencefalograma (EEG) interictal e ictal, resultado anatomo-patológico e o seguimento clínico. RESULTADOS: Vinte e cinco pacientes foram avaliados, 13 eram do sexo feminino. A idade média de início da epilepsia foi de 4.4±2.0 anos. Não houve diferenças significativas entre os pacientes com evolução lenta ou rápida considerando-se a idade de início da epilepsia (p=0,79), idade da cirurgia (p=0,24), duração da epilepsia (p=0,06) e tempo de seguimento (p=0,40). Não houve correlação entre a presença de alterações bilaterais ou ausência de descargas ao EEG e o seguimento pós-operatório (p=0,06). Vinte e três pacientes foram submetidos à cirurgia. O tempo médio de seguimento foi de 75,3 meses. Onze pacientes evoluíram com controle total das crises. Doze pacientes permaneceram com crises que consistiram de clonias faciais sutis (6 pacientes), crises tônico-clônicas hemigeneralizadas ocasionais (3 pacientes) ou crises tônico-clônicas frequentes (3 pacientes). Alterações cognitivas e de linguagem foram observadas em 15 e 12 pacientes após a cirurgia, respectivamente. CONCLUSÕES: este estudo retrospectivo relatou os achados clínicos, eletrográficos e a evolução de 23 pacientes. Controle satisfatório das crises foi obtido em 14 pacientes. Três pacientes tiveram resposta parcial com a cirurgia e cinco pacientes mantiveram o quadro pré-operatório. Todos os pacientes com envolvimento do hemisfério cerebral esquerdo evoluíram com distúrbio de linguagem e cognitivo.(FAEPA) USP - Hospital das Clínicas da Faculdade de Medicina de Ribeirão PretoCNPqFAEP

Potential role of a cognitive rehabilitation program following left temporal lobe epilepsy surgery

ABSTRACT Research into memory and epilepsy has focused on measuring problems and exploring causes with limited attention directed at the role of neuropsychological rehabilitation in alleviating post-operative memory difficulties. Objectives To assess the effects of a memory rehabilitation program in patients with left temporal lobe epilepsy following surgery. Methods Twenty-four patients agreed to participate and 18 completed the study; nine received memory rehabilitation while nine had no input and were designated as controls. Verbal learning efficiency, naming abilities, memory subjective ratings, ecological activity measures and a language fMRI paradigm were used as outcome measures. Results Improved verbal learning and naming test performance, increase in memory strategy use and improved self-perception were observed following the rehabilitation. Changes in fMRI activation patterns were seen in the rehabilitation group over the long term. Conclusion The findings support the potential role of a cognitive rehabilitation program following left temporal lobe surgery

Impact of pediatric epilepsy surgery on intellectual efficiency

Introduction. Epilepsy surgery may be a promising alternative therapy for seizure control in patients with refractory seizures, resistant to medication. Cognitive outcome is another important factor in favor of the surgical decision. Aim. To investigate the correlation between seizure outcome and cognitive outcome after epilepsy surgery in a pediatric population. Patients and methods. A total of 59 pediatric patients were retrospectively assessed with the WISC-III (Full Scale, Verbal Scale and Performance Scale) before and, at least, 6 months after surgery. Patients were divided into two groups according whether or not improvement of seizure control after surgery. Data collected for each child included: epileptic syndrome, etiology, age at epilepsy onset, duration of epilepsy and seizure frequency. Results. Comparison using a MANOVA test revealed significant differences across pre-operative Full Scale, Verbal Scale and Performance Scale (p = 0.01) with seizure reduction group performing better than no seizure reduction group. Seizure improvement group achieved significant Performance Scale improvement (p = 0.01) and no seizure improvement group showed significant Verbal Scale worsened after surgery (p = 0.01). Conclusions. Our results suggest that the success of the epilepsy surgery in childhood when the seizure control is achieved may also provide an improvement in the Performance Scale whereas the seizure maintenance may worsen the Verbal Scale

Visualizando a elaboração da linguagem em surdos bilíngues por meio da ressonância magnética funcional

As línguas de sinais são línguas naturais que compartilham as propriedades das línguas orais. Este estudo buscou visualizar as áreas corticais ativadas em surdos bilíngues em Língua Brasileira de Sinais e em Língua Portuguesa. As tarefas envolveram a elaboração da linguagem. Foram feitos treze exames de Imagem por Ressonância Magnética Funcional. Foi utilizada, ainda, uma sequência de imagem ecoplanar para a aquisição BOLD (Blood Oxygen Level Dependent) e, para corregistro, foram buscadas imagens de alta resolução de todo o encéfalo. Os mapas estatísticos foram obtidos com o Modelo Geral Linear, utilizando o programa Brain Voyager.TM A tarefa de elaboração da linguagem em Língua Brasileira de Sinais proporcionou ativações mais significativas do que a tarefa de elaboração em Língua Portuguesa, sugerindo que os surdos bilíngues apresentam maior competência linguística em língua de sinais.Sign languages are natural languages that have the same properties of oral languages. This study aimed to identify the cortical areas activated in bilingual deaf subjects who communicate through Brazilian Sign Language and Portuguese Language. Tasks involved the production of language. Thirteen functional magnetic resonances imaging (fMRI) exams were performed. An Echo Planar Imaging (EPI) sequence was used to obtain the BOLD (Blood Oxygen Level Dependent), associated with a whole brain high resolution imaging for co-register. The statistical maps were obtained using the General Linear Model with Brain VoyagerTM software. The task of producing Brazilian Sign Language provided more significant activations than did the task of producing Portuguese Language, suggesting that bilingual deaf subjects present a higher language proficiency in sign language

Analyzing the association between functional connectivity of the brain and intellectual performance

Measurements of functional connectivity support the hypothesis that the brain is composed of distinct networks with anatomically separated nodes but common functionality. A few studies have suggested that intellectual performance may be associated with greater functional connectivity in the fronto-parietal network and enhanced global efficiency. In this fMRI study, we performed an exploratory analysis of the relationship between the brain's functional connectivity and intelligence scores derived from the Portuguese language version of the Wechsler Adult Intelligence Scale (WAIS-III) in a sample of 29 people, born and raised in Brazil. We examined functional connectivity between 82 regions, including graph theoretic properties of the overall network. Some previous findings were extended to the Portuguese-speaking population, specifically the presence of small-world organization of the brain and relationships of intelligence with connectivity of frontal, pre-central, parietal, occipital, fusiform and supramarginal gyrus and caudate nucleus. Verbal comprehension was associated with global network efficiency, a new finding

Impact of pediatric epilepsy surgery on intellectual efficiency

Introduction. Epilepsy surgery may be a promising alternative therapy for seizure control in patients with refractory seizures, resistant to medication. Cognitive outcome is another important factor in favor of the surgical decision. Aim. To investigate the correlation between seizure outcome and cognitive outcome after epilepsy surgery in a pediatric population. Patients and methods. A total of 59 pediatric patients were retrospectively assessed with the WISC-III (Full Scale, Verbal Scale and Performance Scale) before and, at least, 6 months after surgery. Patients were divided into two groups according whether or not improvement of seizure control after surgery. Data collected for each child included: epileptic syndrome, etiology, age at epilepsy onset, duration of epilepsy and seizure frequency. Results. Comparison using a MANOVA test revealed significant differences across pre-operative Full Scale, Verbal Scale and Performance Scale (p = 0.01) with seizure reduction group performing better than no seizure reduction group. Seizure improvement group achieved significant Performance Scale improvement (p = 0.01) and no seizure improvement group showed significant Verbal Scale worsened after surgery (p = 0.01). Conclusions. Our results suggest that the success of the epilepsy surgery in childhood when the seizure control is achieved may also provide an improvement in the Performance Scale whereas the seizure maintenance may worsen the Verbal Scale

Visualizando a elaboração da linguagem em surdos bilíngues por meio da ressonância magnética funcional

As línguas de sinais são línguas naturais que compartilham as propriedades das línguas orais. Este estudo buscou visualizar as áreas corticais ativadas em surdos bilíngues em Língua Brasileira de Sinais e em Língua Portuguesa. As tarefas envolveram a elaboração da linguagem. Foram feitos treze exames de Imagem por Ressonância Magnética Funcional. Foi utilizada, ainda, uma sequência de imagem ecoplanar para a aquisição BOLD (Blood Oxygen Level Dependent) e, para corregistro, foram buscadas imagens de alta resolução de todo o encéfalo. Os mapas estatísticos foram obtidos com o Modelo Geral Linear, utilizando o programa Brain Voyager.TM A tarefa de elaboração da linguagem em Língua Brasileira de Sinais proporcionou ativações mais significativas do que a tarefa de elaboração em Língua Portuguesa, sugerindo que os surdos bilíngues apresentam maior competência linguística em língua de sinais