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:
Type I (classic) lissencephaly typically presents with marked hypotonia and paucity of movement.
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 .
- classification system for malformations of cortical development
- lissencephaly type I - subcortical band heterotopia spectrum
- band heterotopia
- lissencephaly type II
- Lissenzephalie Typ 2
- Miller-Dieker lissencephaly syndrome
- Lissenzephalie Typ 1
- agyria-pachygyria complex
- pachygyria - lissencephaly spectrum
- neuroradiology curriculum
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- Heterotopie der grauen Substanz
- Neu-Laxova syndrome
- agyria - pachygyria spectrum
- MRI features of lissencephaly with cerebellar hypoplasia