Brain injury in the preterm infant

Over the past 40 years there has been a dramatic increase in the survival of preterm infants, driven by technological improvements in ventilator management, improved nutrition and high quality nursing care. The increase in survival rates raised the concern that there would be an increase in adverse outcome and neuro- disability, placing a burden on medical and educational resources and on families who have to live with a disabled child. In 1995 a prospective study into the survival and long term neurodevelopmental outcome of all infants in the UK born over a 10 month period at 25 or fewer weeks’ gestation was carried out. These infants were followed up at 21⁄2 and 6 years of age (Wood et al, NEJM, 2000; Marlow et al, NEJM, 2005); in the latter study 241 surviving children were studied at early school age and compared with their classmates who were born at term. Whilst 20% of the children assessed had no problems, 22% had severe disability, such as severe cerebral palsy, very low cognitive scores, blindness or profound deafness. Of the remaining 58%, 24% had moderate disability such as cerebral palsy (but walking), cognitive scores in the special needs range and/or lesser degrees of visual or hearing impairment; 34% had milder problems such as wearing glasses, a squint or low/normal cognitive scores. Minimising adverse neurodevelopmental outcome following preterm birth therefore remains a major challenge for neonatologists.

The most common cerebral lesions affecting preterm infants are a consequence of bleeding into the germinal matrix. Although cystic periventricular leucomalacia (PVL) is less common, it is thought more subtle lesions in the periventricular white matter, often not visible on cranial ultrasound, are responsible for adverse neurodevelopmental outcome in this group of infants.