Teaching Case

Developmental delay, seizures

Presented with severe developmental delay, and epilepsy. MRI examination was performed at 1.5 Tesla, and T1 and T2-weighted images were acquired as well as a PSIF sequence. PSIF is an anisotropic diffusion sequence(reverse FISP, fast imaging in steady state precession).

The normal cerebral cortex is approximately 3-5mm in thickness. A cortical thickness of 5-8 mm could reflect polymicrogyria, and thicker cortices are usually seen in agyria and pachygyria (care should be exercised to not to overestimate cortical thickness in oblique sections). In agyria the brain surface is smooth without any normal gyrus. In pachygyria usually a a few normal-appearing gyri are present especially in the occipital and temporal lobes. Changes consistent with agyria and pachygyria are usually seen together, which is referred to as lissencephaly. Lissencephalic brains may be in isolation or may be associated with Walker-Waburg syndrome (hypotonia, ocular malformations, encephalocele, and hydrocephalus), and Fukuyama type muscular dystrophy (congenital muscular dystrophy, and ocular malformations). Also, lissencephalic brains may be very small in size (microbrain), or may show extremely thin cortices (micrencephalia vera).