الفهرس 
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Abstract
FCD has come to be recognized as one of the most common causes of seizures in children with intractable epilepsy, accounting for nearly 80% of all surgically treated cases in children under 3 years of age. As a distinct subtype of malformation of cortical development, FCD differs from the rest of this spectrum in that it is not associated with diffuse abnormal gyration, but rather with subtle focal changes that at times can only be appreciated microscopically. Similar to other MCDs, FCD is thought to be secondary to genetic, ischemic, toxic, or infectious insult during cortical development.
Many pathologic classifications of cortical dysplasias have been made in an attempt to unify the histopathologic findings with the electro-clinical presentation and the imaging features, as the diagnosis is usually made retrospectively after surgery. The most recent of these classifications is the 2011 ILAE classification system, which also accounts for new molecular and developmental insights. Regardless of the underlying disease, accurate delineation of the epileptogenic zone by imaging is the most reliable predictor of surgical outcome. The most common MR features are thickening of the cortex, blurring of the grey/white matter boundary, signal changes, tapering white matter signal towards the ventricle (trans-mantle sign), focal hypoplasia/focal atrophy. The trans-mantle sign is the only specific finding and is almost exclusively found in FCD Type IIb. However, especially at 1.5T, MRI is neither sensitive nor specific for differentiating between the various types of FCD. New advances in neuroimaging have provided increased sensitivity for identifying CDs of all types, which is of utmost importance in pre-surgical evaluation. For this reason, there has been ongoing interest in utilizing new advanced MRI techniques to improve the ability to identify, diagnose, characterize, and delineate cortical dysplasias. Technologic gains such as multichannel coils and higher field strengths (3T, 7T, and
greater) coupled with advanced post-processing schemes and newer imaging sequences such as arterial spin labeling (ASL), susceptibility weighted imaging (SWI) and diffusion tensor/spectrum imaging (DTI/DSI) are likely to increase yield. Although all of the techniques mentioned earlier have the potential to improve epileptogenic lesion identification, delineation, and characterization, it is the multimodal combination of techniques, such as MEG and PET, in conjunction with a well-integrated team of experts that yields the most successful results. As we move into an era of molecularly targeted therapies and diagnosis, the rapidly advancing field of neuroimaging is well positioned to play an important role in providing a window into these microscopic events.