NeuroradiologyAgyria
(also called complete lissencephaly), the complete absence of gyri on the surface of the brain. The term should be referred only to type I lissencefaly. Agyria manifests clinically with severe mental retardation, microcephaly, hypotonia and refractory seizures with an early onset in the first year of life. MR shows a smooth brain surface with thickening of the
cerebral cortex and a straight grey/white matter junction; shallow abnormally vertical sylvian fissures giving the brain a figure-of-eight appearance. See
lissencephaly, and
neuronal migration disorder.
FS