= double-stranded DNA virus with replication inside cell nucleus causing a lytic productive / latent infection; member of Herpes viridae family (with varicella-zoster virus, Epstein-Barr virus, herpes simplex virus types 1 and 2)
◊Most common intrauterine infection in USA!
Incidence: 0.4–2.4% of liveborn infants; 40,000 babies born each year with CMV infection in USA
Transmission:
- horizontally by contact with saliva / urine or sexually
- vertically from mother to fetus transplacentally; spreads hematogenously throughout fetus
- Outcome poorer if infected during first half of pregnancy at a younger gestational age!
Histo: necrotizing inflammatory process
Predilection: CMV has special affinity for metabolically active neuroblasts of germinal matrix
Prenatal screening:
- antibodies in 30–60% of pregnant women;
- primary CMV infection in 2.5% of pregnant women
Postnatal screening:
- 10% of neonates excrete virus;
- 1.6% of newborns shed CMV in urine / saliva
- asymptomatic + subclinical (90%)
- symptomatic at birth (10–15%):
- sensorineural deafness, mental retardation, neurologic deficits, seizures
- ocular abnormalities (15–50%): chorioretinitis, optic neuritis, optic atrophy, hypoplasia + coloboma of optic nerve, anterior uveitis, anophthalmia, microphthalmia, cataracts, cyclopia
- jaundice, hemolytic anemia, thrombocytopenic purpura
- Leading cause of brain disease + hearing loss in children!
- symptomatic in adults (in up to 15%):
- fever, pharyngitis, lymphadenopathy, polyarthritis
- intrauterine growth retardation
- hepatosplenomegaly (nontender)
- ascites
- hydrops
- pneumonitis
Dx: polymerase chain reaction analysis of CSF / urine / saliva / blood to detect CMV DNA; positive viral culture within first 2 weeks of life
Rx: no effective treatment for maternal infection
DDx: toxoplasmosis, teratoma, tuberous sclerosis, Sturge-Weber syndrome, venous sinus thrombosis, microcephaly intracranial calcification syndrome
Cause: HIV infection; immunosuppression; solid organ / bone marrow transplantation
- mental status change
Role of CT: rule out mass lesion / substantial cerebral edema before planned lumbar puncture
- meningoencephalitis (most frequently):
- cortical + subcortical areas of hypointensity on T1WI + hyperintensity on T2WI
Location: especially frontal + parietal lobes - diffuse leptomeningeal enhancement
- cortical + subcortical areas of hypointensity on T1WI + hyperintensity on T2WI
- ventriculoencephalitis (with advanced HIV infection):
- cerebral volume loss
- ventriculomegaly
- periventricular enhancement
- enhancing mass lesions (only with advanced AIDS)
DDx: lymphoma / other neoplasm, pyogenic abscess - polyradiculopathy (in adults)
Congenital CMV Infection of CNS
- intracranial calcifications (34–70%):
- Most common finding of congenital CMV infection!
- thick and chunky postinflammatory periventricular Ca2+
- faint punctate Ca2+ in basal ganglia + thalami + parenchyma
Associated with: developmental delays
- cerebral atrophy
- ventriculomegaly (in up to 45%)
- 2nd most common finding of congenital CMV infection!
Cause: ventriculitis; obstruction by inflammatory exudate; brain atrophy - microcephaly (in up to 27%)
Cause: encephaloclastic effect of virus / disturbance of cell proliferation - cerebral volume loss
- cerebellar volume loss (in up to 67%):
- widening of cerebellar folia
- expansion of CSF spaces in posterior fossa
- severe diffuse hypoplasia / dysplasia of cerebellum
- ventriculomegaly (in up to 45%)
- neuronal migrational disorders (in up to 10%)
- lissencephaly = smooth surface with absence of sulcation of a thin / thickened cortical mantle
Congenital CMV Imaging Findings versus Time of Infection
Estimated Gestational Age: <18 wks 18–24 wks >26 wks √periventricular Ca2+ + + ++ √ventriculomegaly ++ + √lissencephaly + thin cortex + √cerebellar hypoplasia + + √delayed myelination + + √polymicrogyria + √schizencephaly (rare) + √dysmyelination + √leukoencephalopathy + - pachygyria = broad gyri + partial sulcation
- diffuse / focal polymicrogyria = nodular cortical surface + irregular scalloped gray-white matter junction + thickened cerebral cortex
rare: schizencephaly, cortical dysplasia, heterotopia - lissencephaly = smooth surface with absence of sulcation of a thin / thickened cortical mantle
- white matter disease (in up to 22%) = leukoencephalopathy = static nonprogressive focal patchy / confluent areas of hyperintensity on T2WI and FLAIR images in parietal / posterior regions
- periventricular cysts = subependymal cysts (= focal areas of necrosis + glial reaction) commonly in anterior temporal lobes (initially vacuolization → cyst formation)
Location: anterior temporal lobe >occipital pole of lateral ventricles >frontoparietal white matter - ventricular adhesions = intraventricular septa = thin strands of tissue crossing the ventricle ← ventriculitis
- lenticulostriate vasculopathy (in up to 27%) = uni- / bilateral curvilinear highly echogenic streaks within basal ganglia + thalami
Cause: mineralizing vasculopathy with deposition of amorphous basophilic material in arterial walls
Prognosis: poor neurologic outcome with microcephaly + calcifications