The sylvian fissures are widened. Parietooccipital sulcation is absent.
None exists except lissencephaly.
A markedly premature brain would not have this bizarre thickened cortex. 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.