[Imaging evolution and incidence of periventricular leukomalacia in preterm infants]

During five years from 1985 to 1989, serial brain echography was performed in 399 preterm infants with gestation less than 35 weeks at Kitasato University Hospital. Twenty-eight (7.0%) infants without periventricular hemorrhage were revealed as having spastic cerebral palsy by neurodevelopmental evaluation in later infancy. Of these 28 infants, the following neonatal brain echographic findings were obtained; cystic periventricular leukomalacia in 14, and persistent periventricular echogenicity without cystic formation in 4. However, neonatal brain echograms were completely normal in 10 infants. Magnetic resonance (MR) studies were performed to find cerebral lesions in all 28 infants. Periventricular high intensity areas on T2 weighted images, irregularity of ventricular wall, ventricular dilatation, decreased volume in periventricular white matter and thinning of the posterior body of corpus callosum were common findings in those infants, and compatible with the MR findings of periventricular leukomalacia (PVL). Therefore our infants with no brain echo abnormality might have had small PVL lesions not detected by brain echography. The reliability of brain echography is still controversial in the diagnosis of nonhemorrhagic PVL. Careful follow up is essential even in the infant with no brain echo abnormality.