Cytomegalovirus (CMV) is a DNA herpes virus that commonly infects people of all ages, with current estimates of seroprevalence being anywhere from 40%-100% of the population. It can be acquired in multiple ways, including: body fluids, organ transplantation, sexual contact, and placental transmission. In immunocompetent hosts, the disease typically runs its course in a benign fashion with most hosts being asymptomatic, or occasionally a mild illness with fever, sore throat, fatigue and swollen glands. Congenital CMV infection occurs in approximately 1% of births and is mainly a result of a primary maternal CMV infection around 32% versus secondary infection of about 1%. Transmission is more likely to occur in the 3rd trimester, but sequelae tend to be worse when infection occurs in the 1st trimester. Overall, roughly 10% of neonates with congenital CMV infections will be symptomatic. When symptomatic, clinical findings include: jaundice, microcephaly, small for gestational age, hepatosplenomegaly, petechiae, lethargy, and sensorineural hearing loss. In some cases, there may be later onset of sequelae, such as sensorineural hearing loss and developmental delay.
Generally, on MRI, features commonly seen include: microcephaly, migrational abnormalities (lissencephaly, pachygyria and schizencephaly), white matter lesions (mainly parietal or posterior white matter involvement with spared rim in immediately periventricular and subcortical white matter), ventriculomegaly, subarachnoid space enlargement, demyelination, periventricular and temporal pole cysts.
Fetuses that are infected in the first half of the 2nd trimester have agyria or lissencephaly with a thin cortex, hypoplasia of the cerebellum, delayed myelination, ventriculomegaly, germinal zone cysts and periventricular calcifications. In the middle of the 2nd trimester, less ventricular dilatation, less consistent cerebellar hypoplasia and more typical polymicroglia is seen. Infection near the end of gestation or postnatally have normal gyral patterns, mild ventricular and sulcal prominence, and damaged periventricular or subcortical white matter with scattered periventricular calcification or hemorrhage.
References
1. Barkovich AJ, Pediatric neuroimaging
2. https://www.cdc.gov/cmv/congenital-infection.html
3. https://www.uptodate.com/contents/congenital-cytomegalovirus-infection-clinical-features-and-diagnosis?search=congenital%20cmv&source=search_result&selectedTitle=1~54&usage_type=default&display_rank=1