The premature brain: developmental and lesional anatomy

Abstract

Neurodevelopmental outcome in prematures who suffer from a neonatal brain injury depends on the lesion itself, and on how the lesion interferes with the still developing functional anatomy. Most of the neuronal migration is completed by midgestation. The second part of the gestation corresponds to the development of the connectivity and sulcation, of the maturation of the oligodendrocytic lineage and of the microglia, and of the vascular bed in the parenchyma beyond the germinal matrix. In this paper, the main processes of the developmental anatomy of the premature brain are reviewed, and are correlated with the findings in a prospective series of 105 premature infants born between 24 and 32weeks of gestation, and serially examined with MR imaging at birth, at term-equivalent age, at 2years, and at 4years. Special emphasis was placed (1) on the intraventricular hemorrhage because of the resulting destruction of the germinal matrix and its impact on the late cellular production, (2) on the periventricular venous hemorrhagic infarction because of the selective destruction of the intermediate zone which is associated, and (3) on the apparently perivenous punctate lesions of the white matter because they involve the intermediate zone also, because they have no convincing explanation yet, and because the microglia seems to be associated with their pathogenesis. These deep venous injuries appear to preserve the subplate zone, which is likely to be a significant element to consider in the perspective of the neurodevelopmental outcome.