Cranial ultrasound in preterm infants: long term follow up.
One hundred and twenty nine high risk preterm infants (gestational ages 26-36 weeks, mean 31.2 weeks; birth weights 800-3880 g, mean 1490 g) were studied by cranial ultrasound during the neonatal period, over a period of one week to three months, and at the age of 1 year. Neonatal ultrasound scanning was performed with an ATL Mk III real time echoscope, and follow up ultrasound scans at the age of 1 were performed with an Octoson static compound scanner. The neonatal scans of 66 infants were abnormal. Cerebroventricular haemorrhages were detected in 53 infants and other lesions in 19, six of whom also had haemorrhages. Posthaemorrhagic changes developed in 30 infants. The follow up scans at 1 year were abnormal in 27 children. One large parenchymal cyst was detected. All 27 scans showed ventricular dilatations; 19 were asymmetrical. About 95% of the children with normal neonatal scans and 60% with abnormal neonatal scans had normal scans at 1 year. The size and shape of the ventricular system had changed in 20% of all infants. As no major changes were seen in the ultrasound images of those studied beyond the age of 2 months cranial ultrasound follow up in high risk preterm infants should therefore be continued until the age of 2-3 months; follow up beyond that age would only rarely be necessary.