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 characte ristics of localization, distribution, and size of echodense and echolucent abnormalities enable individuals to be designated as having either periven tricular hemorrhagic infarction or periventricular leukomalacia and (2) the characteristics of periventricular hemorrhagic infarction and periventricu lar 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 sc an read independently by at least two ultrasonographers. The ultrasound dat a collection form diagrammed six standard coronal views. The cerebrum was d ivided into 17 zones in each hemisphere. All abnormalities were described a s being echodense or echolucent and were classified on the basis of their s ize, laterality, location, and evolution. Eight percent (134/1607) of infan ts had at least one white-matter abnormality. The prevalence of white-matte r disease decreased with increasing gestational age. Most abnormalities wer e small or medium sized and unilateral; only large echodensities tended to be bilateral and asymmetric. Large abnormalities, whether echodense or echo lucent, were more likely than smaller abnormalities to be widespread, and t he extent of cerebral involvement was independent of whether abnormalities were unilateral or bilateral. Large abnormalities were relatively more like ly than small abnormalities to involve anterior planes. Small abnormalities , whether echodense or echolucent, or whether unilateral or bilateral, pref erentially occurred near the trigone. Using the characteristics of location , size, and laterality/symmetry, we were able to allocate only 53% of infan ts with white-matter abnormalities to periventricular hemorrhagic infarctio n or periventricular leukomalacia. Assuming that periventricular leukomalac ia and periventricular hemorrhagic infarction are independent and do not sh are risk factors, and that each occurs in approximately 5% of infants, we w ould have expected 0.25%, or about 4 individuals, to have abnormalities wit h 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 periventric ular hemorrhagic infarction or periventricular leukomalacia only. Periventr icular hemorrhagic infarction contributes to the risk of periventricular le ukomalacia occurrence, or the two sorts of abnormalities share common risk antecedent factors. The descriptive term echodense or echolucent and the ge neric term white-matter disease of prematurity should be used instead of pe riventricular leukomalacia or periventricular hemorrhagic infarction when r eferring to sonographically defined white-matter abnormalities.