Imaging of Congenital Malformations of the Brain.

Brain formation is a continuous and complicated process that is historically categorized by the timing of development. The earliest disorders of dorsal induction occur in the first month of gestation and include anencephaly and cephalocele. Disorders of ventral induction occur during the second month of gestation and include the holoprosencephaly and septo-optic dysplasia spectrums. The third and longest timeframe include the disorders of neuronal migration and proliferation (gestational weeks eight-25) and include malformations of cortical development: lissencephaly, polymicrogyria, schizencephaly, gray matter heterotopia, and corpus callosal dysgenesis. This review will highlight the neuroimaging of these malformations.