Congenital Microcephaly with a Simplified Gyral Pattern: Associated Findings and Their Significance

A 10-year-old girl with microcephaly. A, Sagittal T1-weighted image shows extreme microcephaly. The corpus callosum is fully formed but diffusely thin. B and C, Axial T2-weighted images show a moderately simplified gyral pattern with too few sulci but normal cortical thickness (measured at <3 mm). Symmetric posterior horn−dominant lateral ventricular enlargement is shown. White matter volume is severely reduced. D, Coronal T2-weighted image shows a disproportionally large cerebellum.

A 1-month-old girl with microcephaly, global developmental delay, and seizures. A, Sagittal T1-weighted image shows extreme microcephaly. The corpus callosum is partially formed, the rostrum is absent, and other parts (genu, body, and splenium) are diffusely thin. B, Axial T2-weighted image shows a severely simplified gyral pattern; sulci are both too few and too shallow. Although myelination is shown in the posterior limb of the internal capsule, the abnormal high intensity of the white matter is observed diffusely and the volume of the white matter is severely diminished. C, Coronal T2-weighted image shows a disproportionally large cerebellum.