Perinatal Infections

Abstract

Despite major improvements in prenatal diagnosis, medications, and vaccine programs efficacy, perinatal infections of the CNS remain a significant cause of damage to the developing brain. Concerning congenital infections, the acronym TORCH is used to describe the main infecting agents where T stands for Toxoplasma gondii, O for other infections (including syphilis, varicella-zoster, and parvovirus B19), R for Rubella, C for Cytomegalovirus, and H for Herpes virus. Nowadays there is an increasing interest for Zika virus as a congenital infectious agent, given the recent outbreak in South America. The stage of development of the fetal brain at the time of the insult is more important than the virulent potential, and indeed the very nature, of the infecting agent. Infections occurring early in fetal life will result in congenital malformations, whereas infections occurring in late gestation will cause destructive lesions. All infecting agents reach the fetal brain through the transplacental route following primarily maternal infection, except for herpes virus which is transmitted during parturition.

Bacterial brain infections are a serious and common event in the neonatal population. Meningitis is more common in the neonatal period of life than any other time. Although the mortality rate has declined over the last decades, the morbidity rate remains almost the same. Bacterial meningitis is still considered to be a devastating disease, leaving survivors with serious neurologic sequelae. The complications of bacterial meningitis reflect the pathogenetic pathways and consist of effusion and empyemas, ventriculitis, hydrocephalus, venous thrombosis, and venous and arterial infarctions. Abscess formation can be a result of meningitis causing hemorrhagic necrosis.

The most common fungal infections during the neonatal period are caused by Candida species. Candida septicemia is frequent among neonates in the intensive care unit, especially among preterm infants of low birth weight. Additional risk factors include long-term treatment with wide spectrum antibiotics and steroids, parenteral nutrition, tracheal intubation, and vascular catheters.

Clinical neuroradiology in fetal and postnatal life plays an important role for the initial diagnosis and follow-up. Radiological techniques include ultrasound (which is the first imaging modality for the initial evaluation and for follow-up) and MRI, which is used to better delineate the lesions and to give information about the prognosis.

This publication is endorsed by: European Society of Neuroradiology (www.esnr.org)