Congenital Malformations of the Brain

Congenital brain malformations are abnormalities present at birth that result from developmental disruptions of the central nervous system at various stages of brain development. Recognizing and understanding the precise sequence of normal brain development is foundational for grouping certain types of brain malformations. Broadly, these include disorders of neurulation (disruptions of neural tube closure), disorders of ventral patterning (derangements of prosencephalic formation, cleavage, and midline development), disorders of cell generation and proliferation (imbalances in neuronal and glial cell proliferation and apoptosis), disorders of neuronal migration (issues with neuronal cells relocation from their place of origin to the cortex or deep gray nuclei), and disorders of cortical organization (problems with neuronal differentiation and aggregation to form the cortical cytoarchitecture). This chapter will review the primary types of brain malformations within this framework and highlight the key imaging features used by the pediatric neuroradiologist to assist in making the correct diagnosis.