Morphometric analysis of the human infant brain: effects of intraventricular hemorrhage and periventricular leukomalacia.

Absolute and relative growth of cerebral structures was assessed morphometrically in 34 neurologically normal live-born infants surviving up to 1 year of age, 20 infants with fatal intraventricular hemorrhage, and 4 with periventricular leukomalacia. In the normal brain, cerebral cortex grew 25% faster than white matter throughout infancy. Thus, to achieve the normal adult size and 1:1 ratio of cortex to white matter, white matter must continue to grow for several years after cessation of cortical growth. Brains with intraventricular hemorrhage or periventricular leukomalacia manifested accelerated growth of gray-matter structures compared with controls. In addition, brains with periventricular leukomalacia had markedly depressed rates of white-matter growth compared with controls of similar age, whereas brains with intraventricular hemorrhage had disproportionate hydrocephalus. The findings suggest that (1) gray-matter growth is accelerated in premature infants with intraventricular hemorrhage or periventricular leukomalacia, perhaps reflecting perinatal stress; (2) periventricular leukomalacia is associated with impaired growth of white matter during a critical period; and (3) sequential quantitative assessment of ventricular size following intraventricular hemorrhage may assist in early recognition of progressive posthemorrhagic hydrocephalus.