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The term epilepsy is applied to a number of conditions that have in common the propensity for the occurrence of epileptic seizures. Epileptic seizures are transient clinical events that result from abnormal, excessive activity of a population of cerebral neurons. They are usually brief, lasting from seconds to minutes, and are marked by the sudden appearance of behavioral manifestations that may be purely motor or affect other brain functions. The abnormal and excessive neuronal activity at the origin of epileptic seizures is inferred from the accompanying clinical and electroencephalographic (EEG) events. Although the clinical events are not always excitatory in nature (e.g., loss of awareness, loss of muscle tone, or loss of language), an epileptic seizure is always the expression of the paroxysmal disorganization of neural networks underlying brain functions [1]. [ABSTRACT FROM AUTHOR]

Brain malformations are extremely polymorphous, and individual cases very often escape rigid categorization. Moreover, several malformations are frequently associated with one another in individual patients, and many are comprised within complex multiorgan syndromes. Although some believe that a purely descriptive diagnostic approach is advantageous [1], classifications are useful to practicing clinicians to make sense of what they see and to approach their patients on the basis of a logical framework. Neuroradiologists have a wellknown propensity for classifications, basically because MRI has proved to be a very powerful and effective tool to attempt radiologic-pathologic correlations. However, classification schemes are continuously challenged by new advances in the understanding of the pathologies they attempt to describe. This has been the case with many disease processes involving the central nervous system (CNS), and especially with brain malformations. Knowledge of the basic molecular and genetic processes that direct normal brain development and, when deranged, result in congenital abnormalities has literally boomed in the past decade. [ABSTRACT FROM AUTHOR]