Defining the nature of the cerebral abnormalities in the premature infant: A qualitative magnetic resonance imaging study

More very-low-birth-weight (VLBW) infants are surviving today, but they could be challenged neurodevelopmentally by cerebral palsy, poor school performance, or behavioral disorder. This longitudinal population-based study used magnetic resonance imaging to determine the nature and extent of abnormalities in white and gray matter of the brain in 100 consecutive premature infants admitted to neonatal intensive care. They made up 98% of all VLBW infants admitted in a 26-month period in 1998 to 2000. Ten healthy term infants were scanned in the week of their due date. Images were graded for white matter (WM) abnormality in a blinded manner by a neuroradiologist experienced in pediatric magnetic resonance imaging, and gray matter abnormality and development were scored independently. Criteria for evaluating WM included cysts, signal abnormality, volume loss, ventriculomegaly, carpus callosal thinning, and myelination. For assessing gray matter, the criteria were signal abnormality, gyration, and the subarachnoid space. The study infants had a mean gestational age of 27.9 weeks and a mean birth weight of 1063 g. Approximately one third of them remained oxygen-dependent at 36 weeks-corrected gestational age. Twenty of the 100 infants had moderate to severe WM injury. On univariate analysis, predictors for moderately severe WM abnormality included lower gestational age, maternal fever, proved infant sepsis at the time of delivery, the need for inotropic support, patent ductus arteriosus, grade III/IV intraventricular hemorrhage, and pneumothorax. Restricted intrauterine growth appeared to have a protective effect. Gray matter abnormality, identified in 27 infants, was closely related to the presence and severity of WM changes. Ten of 11 infants born before 26 weeks gestation exhibited a pattern of significant diffuse WM atrophy, ventriculomegaly, immature gyral development, and an enlarged subarachnoid space. These infants are at the highest risk for subsequent global motor and cognitive impairment. Altered WM structure and closely related abnormalities of gyral development are common findings in VLBW infants. Magnetic resonance imaging at term will likely prove to be a good way of predicting future neurodevelopmental problems and of selecting affected children for early intervention programs.