A 33 week male infant born in a level two neonatal unit demonstrated MRI findings consistent with hypoxic ischaemic encephalopathy (HIE). Further analysis of the clinical case aimed to explore the antenatal, perinatal and postnatal antecedant factors associated with preterm HIE, as well as preterm neuroanatomy and subsequent likely patterns of brain injury seen in preterm infants reported in the literature.
Maternal and baby case notes were carefully reviewed. The mother was seen with premature rupture of membranes and small antepartum haemorrhage. She was examined and found not to be in labour, so was discharged home on oral antibiotics. The male infant was delivered quickly by spontaneous vaginal delivery 57 hours after the rupture of membranes. APGAR scores were 3 at one minute and 4 at ten minutes. Birth weight was 2500 g. The baby was intubated, ventilated and transferred to the neonatal unit. Ventilation was optimised, but he was noted to have myoclonic jerks and to be jittery. He had a stormy neonatal course with several failed extubations and an abnormal agonal breathing pattern.
MRI brain showed diffusely abnormal basal ganglia, hypothalamic and thalamic and mesotemporal cortex signal compatible with profound hypoxic ischaemic injury. Long term movement disorder, oropharyngeal dysfunction and movement disorder were thought to be likely outcomes.
Antecedant factors in this case for HIE include chorioamnionitis and the possibility of a placental abruption. The preterm brain is more susceptible to inflammation (such as that caused by chorioamnionitis) and hypoxic ischaemia. CT brain studies have shown the basal ganglia to be more susceptible to hypoxic injury in preterm infants due to blood flow patterns and caudal-cranial neuronal migration. These areas exhibited abnormal signal in the MRI in this case, fitting with previous literature reports.
This case describes a preterm baby of good birth weight with severe HIE. Current treatment for term babies with similar resuscitation would be formal cooling, which has been trialled in gestations of 35 weeks in the USA. This case raises the possibility of formal cooling for lower gestation babies. It also highlights the importance of knowledge of preterm neuroanatomy in predicting preterm brain injury and MRI in predicting future outcome and care needs of these babies, to allow parents to plan for their futures.