Case contributed by Amro Omar
Diagnosis certain


Generalized tonic-clonic seizures and developmental delay.

Patient Data

Age: 3 months

CT demonstrates primitive Sylvian fissures leading to an "hour-glass" configuration of the brain. Ventriculomegaly, frontal pachygyria, and occipital agyria are also presented. 


MRI shows only a few shallow sulci and shallow Sylvian fissures, the cortex is markedly thickened measuring 12-20mm (rather than the normal 3-4mm), and diffuse white matter demyelination with white matter cysts. 

Case Discussion

Lissencephaly type I is a heterogeneous group of disorders of cortical formation characterized by a smooth brain, with absent or hypoplastic sulci and is strongly associated with subcortical band heterotopia (see classification system for cortical malformations).

Beware that agyric (smooth) cortex is normal up to 26 weeks of gestation age.

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