The lissencephaly-pachygyria spectrum is a useful way to describe the spectrum of diseases that cause relative smoothness of the brain surface and includes:

  • agyria: no gyri
  • pachygyria: broad gyri
  • lissencephaly: smooth brain surface

It is a basket term for a number of congenital cortical malformations characterized by absent or minimal sulcation.

Lissencephaly-pachygyria can be further divided into types I (classic) and type II (cobblestone). They differ in clinical presentation, underlying genetic abnormalities, as well as microscopic and macroscopic (including imaging) appearances . They themselves represent a heterogeneous group of disorders. This article highlights a few generalities and outlines the differences between the two types, which are otherwise discussed separately:

Clinical presentation

Type I (classic) lissencephaly typically presents with marked hypotonia and paucity of movement.

Type II lissencephaly is associated with muscular dystrophy-like syndromes and includes Walker-Warburg syndromeFukuyama syndrome, and muscle-eye-brain (MEB) disease .

Radiographic features

Although lissencephaly can be identified on all cross-sectional modalities (antenatal and neonatal ultrasound, CT and MRI), MRI is the modality of choice to fully characterize the abnormalities.


Type I and type II lissencephaly demonstrate vaguely similar appearances (thus the common term lissencephaly) but different macroscopic and imaging appearances are visible.

Type I (classic) lissencephaly can appear as the classic hourglass or figure-8 appearance or with a few poorly formed gyri (pachygyria) and a smooth outer surface. It is usually associated with band heterotopia.

Type II lissencephaly, on the other hand, has a microlobulated surface referred to as a cobblestone complex. Band heterotopia is not evident and the cortex is thinner than in type I.

History and etymology

Lissencephaly is derived from the Greek word λισσος (lissos), meaning smooth .

See also

Siehe auch:
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