cytomegalovirus encephalitis

Toddler with

seizures. Axial T1 MRI without contrast of the brain (left) shows gyral thickening compatible with pachygyria and ventriculomegaly. Axial T2 MRI (right) shows increased bright signal throughout the white matter, compatible with delayed myelination. There are also several areas of punctate low signal along the periphery of the lateral ventricles posteriorly, compatible with foci of calcification, which were confirmed on GRE images (not provided). The diagnosis was cytomegalovirus encephalitis, which most likely occurred in the first trimester.

pediatricimaging.org • CC-by-nc-sa 4.0

HIV/AIDS (CNS

manifestations) • CMV ventriculitis and encephalitis - Ganzer Fall bei Radiopaedia

Gaillard, F. CMV ventriculitis and encephalitis. Case study, Radiopaedia.org. (accessed on 20 Oct 2022) https://doi.org/10.53347/rID-5416 • CC by-nc-sa 3.0 (modified)

Preschooler

who had cytomegalovirus infection in-utero. Axial T2 MRI without contrast of the brain show thickening and abnormal sulcation of the perirolandic gray matter diffusely bilaterally. There is also evidence of perisylvian fissure syndrome bilaterally.The diagnosis was diffuse polymicrogyria in a patient with cytomegalovirus encephalitis.

pediatricimaging.org • CC-by-nc-sa 4.0

Magnetic

resonance imaging patterns of paediatric brain infections: a pictorial review based on the Western Australian experience. T2 hyperintensity in supratentorial white matter—with neuronal migration abnormality (Pattern 4A). Case 1: 11-week-old infant with bilateral sensorineural hearing loss on newborn testing. Guthrie test was positive for CMV. T2-weighted imaging (a–c) demonstrated polymicrogyria with diffuse white matter hyperintensity and cystic change in the left anterior temporal pole. Clinical notes at 14 months of age indicated developmental delay. Case 2: 4-month-old infant with microcephaly, developmental delay and hypertonia under investigation. Guthrie test was positive for CMV. T2-weighted imaging (d) demonstrated polymicrogyria with diffuse white matter hyperintensity and subtle periventricular calcifications (arrows)

insightsimaging.springeropen.com • CC-by-4.0

Magnetic

resonance imaging patterns of paediatric brain infections: a pictorial review based on the Western Australian experience. T2 hyperintensity in supratentorial white matter—without neuronal migration abnormality (Pattern 4B). Case 1: 2-year-old child with congenital left sensorineural hearing loss. Guthrie test was positive for CMV. T2-weighted imaging (a, b) demonstrated cystic change at the right anterior temporal pole, with bilateral parietal and periventricular white matter hyperintensity. Case 2: 2-year-old child with developmental delay. Guthrie test was positive for CMV. T2-weighted imaging (c, d) demonstrated cystic change at the right anterior temporal pole, with bilateral peritrigonal white matter hyperintensity

insightsimaging.springeropen.com • CC-by-4.0

Radiopaedia • CC-by-nc-sa 3.0 • de

Cytomegalovirus (CMV) encephalitis is a CNS infection that almost always develops in the context of profound immunosuppression.

This article focus on adult infection. CMV is also one of the most frequent prenatal infections, which is discussed separately: congenital CMV infection.

Epidemiology

It is extremely rare to involve immunocompetent individuals.

Clinical presentation

Presentation is variable, however generalized cognitive decline is most frequent. Focal neurological signs and cranial nerve palsies are uncommon to rare.

At autopsy active CMV infection is also seen systemically although clinical manifestations are variable:

CMV adrenalitis (92%)
CMV pneumonitis (42%)
CMV retinitis (58%)

Pathology

Typically, before CMV infections become clinically apparent the patient's CD4 count typically reaches below 50/mm . CMV infects the entire neuraxis (brain, spinal cord, meninges, nerve roots, eye) and therefore has variable presentation.

Etiology

Cytomegalovirus is a DNA virus belonging to the herpesviruses group, and is also known as Human Herpesvirus 5 (HHV-5). It is found in all geographic locations and socioeconomic groups, and infects between 50-80% of adults in the United States as indicated by the presence of antibodies in much of the general population.

Radiographic features

Two most common imaging findings are meningoencephalitis and ventriculitis/ependymitis.

MRI

In CMV encephalitis, there is usually only non specific increased T2/FLAIR signal in the white matter. If ventriculitis is also present then enhancement of the ependymal surface and hydrocephalus may also be seen.

high T2 white matter change most prominent in a periventricular distribution
no enhancement (unless ventriculitis present, in which case 30% or so will enhance)
no mass effect (often seen with concurrent atrophy)

Appearances are similar to HIV encephalitis, although usually CMV occurs in patients with a longer duration of disease, and lower CD4+ counts.

Differential diagnosis

Other white matter changes in HIV, especially :

HIV encephalitis
progressive multifocal leukoencephalitis (PML)
primary CNS lymphoma: periventricular but has mass effect and enhances

Practical points

Particularly in a profoundly immunocompromised patient, ventriculitis characterized by high T2/FLAIR signal and post contrast enhancement is highly suggestive of CMV infection.