Topography of cerebral white-matter disease of prematurity studied prospectively in 1607 very-low-birthweight infants.

The objective of this study was to evaluate to what extent (1) the characteristics of localization, distribution, and size of echodense and echolucent abnormalities enable individuals to be designated as having either periventricular hemorrhagic infarction or periventricular leukomalacia and (2) the characteristics of periventricular hemorrhagic infarction and periventricular leukomalacia are independent occurrences. The population for this study consisted of 1607 infants with birthweights of 500 to 1500 g, born between January 1991 and December 1993, who had at least one cranial ultrasound scan read independently by at least two ultrasonographers. The ultrasound data collection form diagrammed six standard coronal views. The cerebrum was divided into 17 zones in each hemisphere. All abnormalities were described as being echodense or echolucent and were classified on the basis of their size, laterality, location, and evolution. Eight percent (134/1607) of infants had at least one white-matter abnormality. The prevalence of white-matter disease decreased with increasing gestational age. Most abnormalities were small or medium sized and unilateral; only large echodensities tended to be bilateral and asymmetric. Large abnormalities, whether echodense or echolucent, were more likely than smaller abnormalities to be widespread, and the extent of cerebral involvement was independent of whether abnormalities were unilateral or bilateral. Large abnormalities were relatively more likely than small abnormalities to involve anterior planes. Small abnormalities, whether echodense or echolucent, or whether unilateral or bilateral, preferentially occurred near the trigone. Using the characteristics of location, size, and laterality/symmetry, we were able to allocate only 53% of infants with white-matter abnormalities to periventricular hemorrhagic infarction or periventricular leukomalacia. Assuming that periventricular leukomalacia and periventricular hemorrhagic infarction are independent and do not share risk factors, and that each occurs in approximately 5% of infants, we would have expected 0.25%, or about 4 individuals, to have abnormalities with characteristics of both periventricular leukomalacia and periventricular hemorrhagic infarction, whereas we found 63 such infants. Most infants with white-matter disease could not be clearly designated as having periventricular hemorrhagic infarction or periventricular leukomalacia only. Periventricular hemorrhagic infarction contributes to the risk of periventricular leukomalacia occurrence, or the two sorts of abnormalities share common risk antecedent factors. The descriptive term echodense or echolucent and the generic term white-matter disease of prematurity should be used instead of periventricular leukomalacia or periventricular hemorrhagic infarction when referring to sonographically defined white-matter abnormalities.