Frequency of neuropathological abnormalities in very low birth weight infants.

The occurrences of histologic changes in the central nervous system of very low birth weight infants (500 to 1500 grams) according to gestational age and postnatal age are incompletely reported. In order to better understand the abnormalities present in this patient population, the brains of 67 very low birth weight infants who died after having had at least one cranial ultrasound scan were studied. More than half the infants were born at gestational ages of 24 to 26 weeks, and only 28% died within 24 hours (h) of birth. The slides of the brains of all 67 infants were reviewed simultaneously by 3 neuropathologists who had to agree on the presence and/or absence of each histologic characteristic. Among infants who died within 24 h of birth, fully one quarter had parenchymal hemorrhage, 42% had petechial hemorrhages in the white matter, and more than 20% had hypertrophic astrocytes. These data indicate that in utero, prepartum, injury to the nervous system was common. Compared with infants who died before the sixth day, those who survived at least 6 days were twice as likely to have moderate/severe ventriculomegaly, rarefaction, amphophilic globules, hypertrophic astrocytes, macrophage foci, coagulative necrosis, and hemorrhagic necrosis than those who died before the 7th postnatal day. Parenchymal hemorrhage and moderate/severe ventriculomegaly decreased in frequency with increasing gestational age. On the other hand, the older the gestational age, the higher the likelihood of finding amphophilic globules, hypertrophic astrocytes, macrophage foci, and zones of coagulative necrosis upon neuropathologic examination. Our data indicate that several central nervous system abnormalities appear to increase with both older gestational age and older postnatal age for infants born weighing less than 1500 grams. We were unable, however, to determine the relative contribution of gestational age and postnatal age to the specific neuropathologic findings in this study.