Lissencephaly

Findings:
Axial and sagittal PD/T2WI show uniformly thickened cortex with only minimal sulcation of the frontal lobes. The sylvian fissures are widened. Parietooccipital sulcation is absent.

Differential Diagnosis:
None exists except lissencephaly. A markedly premature brain would not have this bizarre thickened cortex.

Discussion:
Lissencephaly is the most severe of the migrational anomalies. Affected individuals are profoundly mentally retarded and usually have severe seizure disorders. A global migrational abnormality is postulated, occurring between 11-26 weeks. The cortex is abnormally thickened and sulcation largely absent, with 2-4 instead of the normal 6 cell layers of cortex. Colpocephaly is usually present.
Types:
        I-Miller-Deiker- assd with 17p-
        II-Walker-Warburg- assd with hydrocephalus
        III-isolated
Heterotopia is the most common migrational anomaly. Others include schizencephaly, pachygyria, and polymicrogyria, each occurring at a different stage of fetal development.
 

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