Displasias corticales como causa de epilepsia y sus representaciones en las imágenes: [revisión] / Cortical dysplasia as a cause of epilepsy and its images respresentation: [review]

Epilepsy is a chronic neurological disorder characterized by spontaneous recurrent seizures, which are clinically classified as generalized or partial. Approximately, 30 percent of patients with partial epilepsy is refractory to medical treatment. Within the refractory group we must discard the presence of cortical dysplasia as an underlying cause of the crisis. Cortical dysplasias are a type of malformations of cortical development (MCD) that are increasingly recognized as a cause of refractory epilepsy. From the radiological point of view this kind of pathology is of particular interest since imaging manifestations can be subtle or may show completely normal examinations. The aim of this paper is to review the literature, describing the imaging appearance of the normal cortical development, the classifications of cortical malformations, mainly cortical dysplasias, by highlighting the most frequent radiological signs. We also examine the current role of positron emission tomography (PET) in epilepsy, which in conjunction with magnetic resonance imaging findings and electrophysiological studies are used to define a possible surgical treatment. Through this treatment we expect to be provided with details of histopathological alterations found in the surgical specimen to be compared to the radiographic changes revealed in the pre-surgical study.

La epilepsia es una alteración neurológica crónica caracterizada por crisis convulsivas recurrentes y espontáneas, que clínicamente se clasifican como generalizadas o parciales, dentro de las cuales aproximadamente el 30 por ciento de los pacientes con epilepsia parcial son refractarios al tratamiento médico. Dentro del grupo refractario debemos descartar la presencia de una displasia cortical como causa subyacente de las crisis. Las displasias corticales son un tipo de malformaciones del desarrollo cortical que en forma cada vez más frecuente se reconocen como causante de epilepsia refractaria. Desde el punto de vista radiológico, este tipo de patología tiene especial interés debido a que las manifestaciones imaginológicas pueden ser sutiles o presentar exámenes completamente normales. El objetivo de este artículo es realizar una revisión de la literatura, describiendo el desarrollo cortical normal con su aspecto en imágenes, las clasificaciones de las malformaciones corticales y en especial de las displasias corticales, destacando los signos radiológicos más frecuentes. Además revisaremos el rol en la actualidad de la Tomografía por Emisión de Positrones (PET) en epilepsia, que en conjunto con las imágenes por resonancia magnética y los estudios electrofisiológicos se utilizan para definir un eventual tratamiento quirúrgico, el que una vez realizado nos da detalles del análisis de las alteraciones histopatológicas en la pieza quirúrgica versus las alteraciones radiológicas visualizadas en el estudio pre-quirúrgico.

Imaging of the Ischemic Penumbra in Acute Stroke

One of the main reasons for the soaring interest in acute ischemic stroke among radiologists is the advent of new magnetic resonance techniques such as diffusion-weighted imaging. This new modality has prompted us to seek a better understanding of the pathophysiologic mechanisms of cerebral ischemia/infarction. The ischemic penumbra is an important concept and tissue region because this is the target of various recanalization treatments during the acute phase of stroke. In this context, it is high time for a thorough review of the concept, especially from the imaging point of view.

Functional Brain Mapping Using H2 15O Positron Emission Tomography ( II ): Mapping of Human Working Memory / 대한핵의학회잡지

PURPOSE: To localize and compare the neural basis of verbal and visual human working memory, we erforrned functional activation study using H2O PET. MATERIALS AND METHODS: Repeated H213O PET scans with one control and three different activation tasks were performed on six right-handed narmal volunteers. Each activation task was composed of 13 matching trials. On each trial, four targets, a fixation dot and a probe were presented sequentially and subjects task was to press a response button to indicate whether or nat the probe was one of the previous targets. Short meaningful Korean words, simple drawings and monochromic pictures of human faces were used as matching objects for verbal or visual memory. All the images were spatially normalized and the differences between control and activation states were statistically analyzed using SPM96. RESULTS: Statistical analysis of verbal memory activation with short words showed activation in the left Broca's area, premotor cortex, cerebellum and right cingulate gyrus. In verbal memory with simple drawings, activation was shown in the larger regions including where activated with short words and left superior temporal cortex, basal ganglia, thalamus, prefrontal cortex, anterior portion of right superior temporal gyrus and right infero-lateral frontal cortex. On the other hand, the visual memory task activated predominantly right-sided structures, especially inferior frontal cortex, supplementary motor cortex and superior parietal cortex. CONCLUSION: The results are :consistent with the hypothesis of the laterality and dissociation of the verbal and visual workmg memory from the invasive electrophysiological studies and emphasize the pivotal role of frontal cortex and cingulate gyrus in working memory system.