Cranial imaging in very low birth weight babies: a review

Abstract

Introduction: Periventricular-intraventricular haemorrhage is the most common, well known acute perinatal brain injury in low birth weight infants (LBWI). It is the major cause of death and disability in this group of babies. The other major lesion is periventricular leucomalacia (PVL). The non-invasive technique of cranial ultrasound clarified the diagnosis and assisted in documenting the decline in the 1980's from 34-39% <1500gms or <35 wks GA with intraventricular haemorrhage (IVH) to 15-
20% in most centres by the 1990s. Pathogenesis: Prematurity is the major factor with the associated complications of respiratory distress, with pneumothorax, hyper- and hypotension, hypoxia and ischaemia and reperfusion injury contributing to the development of PVH/IVH. IVH occurs in the first two days and virtually all by one week. IVH occurs in the periventricular region, the germinal matrix which is very vascular with immature blood vessels, poor tissue support for vessels which rupture easily and is associated with coagulopathy. PV haemorrhagic infarction, the grade IV IVH is severe IVH & intense venous
congestion. Periventricular leucomalacia results from a complex interaction of cerebral vascular and cerebral blood flow disturbances following hypoxia, ischaemia and a cytokine cascade. Focal necrotic lesions develop in the periventricular white matter. Other modalities of assessing the brain are by MRI. Diffuse weighted magnetic resonant imaging can detect PVL by day five. Antenatal doppler measurements are a further technique which has shown correlation between fetoplacental blood flow, brain injury and brain volumes in VLBWI. Abnormal umbilical artery/middle cerebral artery pulsatility index was associated with
reduced brain volume and reduced cerebral volume. Outcomes: Of those LBWI who die, 50% have IVH. Of the survivors 20- 40% have IVH. Of those with severe IVH 50% die, moderate IVH 15% die and mild/small IVH 5% die. The outcomes for PVL are related to the duration of oxygen dependency, septicaemia, necrotising enterocolitis (NEC) and are worse with NEC and surgery. The extent of the PVL determines the outcome. Prevention: Maternal factors include aspects of maternal health, health access and antenatal steroids. Neonatal factors include improved neonatal care, correction of metabolic acidosis, careful fluid
administration, careful oxygen delivery, appropriate feeding and management of infections.

O & G Forum Vol. 18 (3) 2008: pp. 87-90