Focal necrosis of the white matter (periventricular leukomalacia): sonographic, pathologic, and electroencephalographic features.

Eleven preterm infants (gestational ages 27-35 weeks) with echogenic paraventricular white matter identified shortly after birth were studied with serial echoencephalograms to fully delineate the sonographic findings characterizing the pathologic stages of white-matter necrosis. Echoencephalograms were compared with autopsy findings and CT scans. Cerebral function was assessed by electroencephalograms and later by neurodevelopmental evaluations. Echogenic areas were observed in the paraventricular white matter in the acute stage. Microscopically, the echogenic white matter consisted of vascular congestion and petechial hemorrhages, but not always with foci of necrosis. Anechoic areas, which characterized the chronic stage, corresponded to cavitary lesions, and these generally appeared within 2 weeks of birth. However, six infants had anechoic lesions by day 4, suggesting that the onset of white-matter damage was antenatal. CT showed mildly decreased attenuation when paraventricular echogenic areas alone or in association with small anechoic areas were observed. Markedly decreased attenuation on CT scans corresponded to large anechoic areas. Resolution of the sonographic and CT findings did not indicate normalization of the white matter since all surviving infants were neurologically abnormal at 1 year. Electroencephalograms with central (rolandic) positive sharp waves were associated with echogenic white matter alone or with evolving anechoic areas. All patients with positive sharp waves on electroencephalograms had large anechoic areas in later studies. Early and serial echoencephalograms are necessary to evaluate white-matter necrosis in preterm infants. When echogenic white matter is identified, electroencephalography can suggest the presence of white-matter necrosis.