Synopsis

Keywords: Neuro: Brain

The objectives of this presentation are to a) review the MRI presentations of common congenital and acquired infections in the neonate and young infant b) understand how presentations of brain infections in the perinatal period are different from presentations in older children and adults, c) recognize the impact of early life neuroinfections on brain development, and d) highlight some common mimics of neonatal brain infections.

Infections of the brain in the neonatal period differs from infections in the older child due to multiple factors including prenatal and perinatal exposure, immature immunological response and ongoing neurodevelopment.
MRI is the ideal modality in demonstrating CNS related infectious injury in neonatal period with excellent tissue contrast. Diffusion weighted imaging and post-contrast sequences are crucial in assessing acute intracranial infectious process. Broadly, CNS infections assessed in the neonatal period may be congenital or acquired.
Congenital infections (TORCH) are transmitted from the mother during gestation and impact neurodevelopment and cerebral maturation. Severity of CNS abnormality in these infections is often dependent on the gestational age of insult. Certain congenital infections such as cytomegalovirus (CMV) show characteristic patterns of periventricular calcifications and cysts and migrational abnormalities.
Acquired neonatal infections may be bacterial, viral or fungal infections. Gram positive (often group B streptococcus, GBS) or gram negative bacterial infections in the neonate may be due to early onset sepsis. Degree of inflammatory response seen in the CNS is often related to onset of infection and presence of other comorbidities such as prematurity. MR imaging findings in bacterial infections include leptomeningeal enhancement, cerebritis and cytotoxic parenchymal injury, purulent intraventricular debris, ependymal enhancement, subdural empyema and venous thrombosis. Common acquired viral infections in the neonate with characteristic imaging findings are due to parechovirus, enterovirus and herpes simplex virus II (HSV II). HSV II infection in the neonate typically results in multifocal cerebritis, without predilection for the temporal lobes, unlike HSV I infection in older children and adults. Fungal infections are much less common in the neonatal period, and often seen in the setting of systemic fungal infections in extremely preterm neonates or infants with immunodeficiency.
In this presentation, we will review some of the typical imaging findings of congenital and acquired brain infections in the neonate and highlight a few mimics.

Acknowledgements

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References

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