Congenital cytomegalovirus infection of the brain: imaging analysis and embryologic considerations.

PURPOSE: To analyze the cortical gyral patterns and myelination patterns in a series of patients with congenital cytomegalovirus infections involving the central nervous system, to correlate them with known developmental events, and to develop a consistent theory regarding their embryogenesis.
METHODS: The MR (11 patients) and CT (four patients) studies of 11 patients with congenital cytomegalovirus infections involving the brain were retrospectively reviewed. Analysis was made of myelination patterns, cortical gyral patterns, other areas of maldeveloped brain, and focal brain lesions.
RESULTS: Lissencephaly was found in four patients. These patients had very thin cerebral cortices, extremely diminished volume of white matter, delayed myelination, small cerebella, and very enlarged lateral ventricles. Focal areas of dysplastic cortex, presumably polymicrogyria, were found in five patients. These patients had slightly thickened irregular cerebral cortices, slightly diminished volume of white matter, delayed myelination, variably small cerebella, and slightly enlarged lateral ventricles. Two patients had normal cerebral cortices, slightly diminished volume of white matter, delayed myelination, normal cerebella, and slightly enlarged lateral ventricles. Periventricular lesions, representing calcification, or perhaps blood, were seen in all groups.
CONCLUSIONS: We postulate that the patients with lissencephaly suffer injury before 16 or 18 weeks gestational age, whereas those with regions of polymicrogyria are injured between approximately 18 and 24 weeks gestational age. Those with normal gyral patterns are probably injured during the third trimester and may have active infections at birth. Moreover, we propose that the finding of cerebellar hypoplasia and myelination delay in association with diffuse lissencephaly or cortical dysplasia should suggest the diagnosis of congenital cytomegalovirus infection.