Cranial ultrasound findings in congenital CMV infection

A one-month-old girl presented for screening cranial ultrasound because of maternal cytomegalovirus (CMV) seroconversion during first trimester of pregnancy and positive urine PCR at birth.

Her birth was uncomplicated at 39 weeks and 4 days. At one month of age fundoscopy showed no evidence of CMV-retinopathy and behavioural audiometry was normal.

Brain ultrasound shows no evidence of ventriculomegaly (Figures 1, 2a & 2b). There are bilateral subependymal cystic changes most predominantly in the caudothalamic groove extending posteriorly (Figures 3-4) without temporal cysts (Figures 2a & 2b). Lenticulostriate vasculopathy is present bilaterally, more so on the right side (Figures 3 & 5).

Vascular parameters in the pericallosal artery are normal, with normal patency of the deep cerebral veins and superior sagittal sinus.

Background

Cytomegalovirus (CMV) is the most common of the neonatal TORCH-infections. [1] Infection is most common in childhood, with only moderate symptoms. Viral latency and reactivation can lead to complications when immunocompromised. [2]

Vertical transmission of CMV from mother to foetus can cause congenital CMV-infection (cCMV). The risk of transmission is highest during the third trimester. [3]

Clinical Perspective

90% of infected newborns are asymptomatic. However, symptoms may develop later in life, with sensorineural hearing loss (SNHL) occurring in 10-15%. [4]

The remaining 10% are symptomatic. Neurological outcome depends on gestational age at transmission. Transmission in the first trimester can cause severe abnormalities due to disruption of embryonic neurodevelopment. Later infection can cause migratory disorders or disrupt myelination and gyration. In general, later infection causes milder symptoms. [5] Clinical presentation can range from mild symptoms such as SNHL and chorioretinitis to epilepsy, cerebral palsy and even death. [6, 7]

Other common symptoms include hepatosplenomegaly, jaundice, and small size for gestational age. [6]

Imaging Perspective

Prenatal cCMV can be suspected by maternal seroconversion or by abnormalities on pregnancy screening ultrasound. [8]

Cranial findings include severe cerebral anomalies, periventricular and subcortical calcifications (33-54% of symptomatic newborns), cysts (temporal, periventricular and subependymal), ventriculomegaly, and lenticulostriate vasculopathy. Extracranial findings include hepatosplenomegaly and hepatic calcifications, both predictive of poor outcome, as well as pericardial effusion, echogenic bowel and ascites. [9]

These findings are not specific to cCMV: calcifications may occur with other infections such as toxoplasmosis, subependymal cysts may be due to haemorrhage, and lenticulostriate vasculopathy may be hypoxic-ischemic. However, the combination of these findings should warrant antenatal PCR of amniotic fluid for a more certain diagnosis. [8]

Close follow-up with sequential ultrasound every two weeks and MRI in the third trimester is recommended. [8] MRI can better depict cortical atrophy, gyration disorders, polymicrogyria, vermian or cerebellar hypoplasia and white matter hyperintensities. [10]

Postnatal confirmation is always necessary, using neonatal urine or saliva PCR during the first 3 weeks of life.  [8, 11]

The initial workup should include a complete blood count and a cranial ultrasound, with particular attention to the aforementioned abnormalities. Additional MRI should be performed if there are clinical neurological findings or if cranial ultrasound is inadequate and additional imaging is deemed necessary. [8]

Outcome

Although several neuroimaging scoring systems exist to predict outcome, there is currently no consensus. [8, 12–14] Detailed reporting of all the previous findings is therefore essential.

Written informed patient consent for publication has been obtained.