- Irregular cortex with numerous small convolutions and shallow sulci.
- Etiology – Encephaloclastic insults such as infection (TORCH), intrauterine vascular accident (MCA occlusion), trauma, metabolic disorders.
- Bilateral perisylvian region is the MC location.
- 2 histological types – Unlayered & 4-layered
- MRI – Overfolded cortex with nodular surfaces & irregular “stippled” gray-white matter interfaces
- D/D – Type 2 lissencephaly, pachygyria, FCD
- Dysplastic grey matter lined CSF-filled cleft that extends from ventricular ependyma to pial surface of cortex.
- Destructive vascular lesions (e.g. MCA occlusion) & infections (e.g. TORCH) before 28 weeks are considered likely etiologies.
- Common association – Absent septi pellucidi
- Open lip – Cleft prominent
- Closed lip – Cleft barely visible
- Cleft follows CSF signal intensity on all sequences
- D/D – Porencephaly (cleft lined by gliotic white matter), arachnoid cyst (displaces adjacent cortex), transmantle heterotopia, deeply infolded polymicrogyria
Rad Reference