Neuroimaging in the high-risk infant: relationship to outcome.

Early brain development involves a genetically programmed, spatially organized, and temporally orchestrated cascade of events. Deleterious prenatal perinatal events may disrupt this sequence and lead to a spectrum of developmental impairments including cerebral palsy and mental retardation. Before the advent of cranial ultrasonography, cranial tomography, and magnetic resonance imaging, neuropathologic correlations were usually established post mortem. These neuroimaging modalities have improved the identification of brain lesions in surviving high-risk preterm and term infants. This has permitted inferences as to timing and pathophysiologic condition of the insult(s) and has facilitated correlations with clinical examination. In very low birth weight infants ultrasonographic abnormalities reflecting white matter damage have the strongest correlations with cerebral palsy: (1) persistent ventricular enlargement or persistent parenchymal echodensities carry a 50% risk for cerebral palsy, and (2) large bilateral cysts in periventricular white matter carry a risk approaching 75% to 95%. In term infants neuroimaging studies show selective vulnerability in cerebral cortex and basal ganglia. This article reviews relationships between neuroimaging findings and outcome to help clinicians interpret the results and to gain an understanding of risk in their patients.