Lissencephaly Type I Classic

  • Etiology: abnormality of neuronal migration characterized by undermigration
  • Imaging: smooth brain surface due to decreased gyri + sulci, ventriculomegaly, hour glass (Figure of 8) brain on axial images, thick cortex – thin outer cortex / cell sparse zone / thick inner cortex, thin white matter, smooth gray white junction
  • Clinical: agyria = complete lissencephayly, pachygyria = incomplete lissencephaly, band heterotopia is milder form of classic lissencephaly

Radiology Cases of Lissencephaly Type I Classic

MRI of lissencephaly type I classic
Axial T1 (left) and axial T2 (right) MRI without contrast of the brain shows a decreased number of gyri and sulci resulting in a nearly smooth brain. There is ventriculomegaly. Overall the brain has an hourglass or figure of 8 appearance.