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Category: Viruses and Viral Pathogenesis
13 Encephalitis in Immunocompromised Patients, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555817831/9781555812409_Chap13-1.gif /docserver/preview/fulltext/10.1128/9781555817831/9781555812409_Chap13-2.gifAbstract:
The immunological defects are variable and include B-cell failure in X-linked agammaglobulinemia and helper T-cell ablation in AIDS. In other cases, such as allograft recipients, the defects are rather more generalized. In all entities considered in this chapter the clinician must balance management of the central nervous system (CNS) disease with the underlying, or associated, systemic disease. Progressive multifocal leukoencephalopathy (PML) is caused by a polyomavirus, one of two varieties of papovaviruses, the other being papillomaviruses. The diagnosis of PML in AIDS should be suspected in a patient with significant suppression of cell-mediated immunity, usually below 100 CD4 lymphocytes per mm3, in whom a subacute onset of multifocal neurological deficits is observed. Congenital infection can be associated with microcephaly and periventricular calcifications in newborns. The subependymal region is a particular locus of congenital infection. Cytomegalovirus (CMV) is the largest of the herpesviruses and takes its name from the characteristic cell enlargement with owl's eye intranuclear viral inclusions that it produces. Neurological involvement with CMV infection in neonates is almost always due to congenital infection, with the risk of clinical disease being great when maternal infection occurs during the first trimester of pregnancy. Cell-mediated immunity plays the predominant role in control of many viral infections. Most of the encephalitic syndromes, in distinction to the leukoencephalitic syndromes, reflect reactivation of viruses in the herpesvirus family. Following death from an encephalitis associated with progressive impairment of mental status and amnesic symptoms, HHV-6-bearing cells were demonstrated in two regions of the brain by immunohistochemistry.
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Close-up view of coronal slice through the brain from a case of PML. The characteristic lesions are present at the junction between cerebral cortex and white matter (arrows).
Close-up view of coronal slice through the brain from a case of PML. The characteristic lesions are present at the junction between cerebral cortex and white matter (arrows).
PML. Lower-power view of section of cerebral cortex and subcortical white matter stained for myelin. Multiple small foci of myelin pallor are present near the junction between cortex and white matter. Luxol fast blue stain.
PML. Lower-power view of section of cerebral cortex and subcortical white matter stained for myelin. Multiple small foci of myelin pallor are present near the junction between cortex and white matter. Luxol fast blue stain.
PML. Area at the margin of a demyelinated zone. Several oligodendrocyte nuclei are enlarged and hyperchromatic, with basophilic intranuclear inclusions (*). Hematoxylin and eosin stain.
PML. Area at the margin of a demyelinated zone. Several oligodendrocyte nuclei are enlarged and hyperchromatic, with basophilic intranuclear inclusions (*). Hematoxylin and eosin stain.
PML. Section stained for the enzyme carbonic anhydrase isoenzyme II, a marker of oligodendrocytes. Some oligodendrocytes show an intense reaction indicating a reactive state. Counterstained with hematoxylin.
PML. Section stained for the enzyme carbonic anhydrase isoenzyme II, a marker of oligodendrocytes. Some oligodendrocytes show an intense reaction indicating a reactive state. Counterstained with hematoxylin.
PML. Low-power view of section of cerebellar cortex showing patchy granule cell loss (outlined). Purkinje cells are also depleted. Hematoxylin and eosin stain.
PML. Low-power view of section of cerebellar cortex showing patchy granule cell loss (outlined). Purkinje cells are also depleted. Hematoxylin and eosin stain.
Electron micrograph of a biopsy from a case of PML showing a nucleus containing both spherical and filamentous polyomavirus particles. Uranyl acetate and lead citrate stain. Courtesy of A. M. Field.
Electron micrograph of a biopsy from a case of PML showing a nucleus containing both spherical and filamentous polyomavirus particles. Uranyl acetate and lead citrate stain. Courtesy of A. M. Field.
MRI of PML. Axial proton density image shows scattered areas of hyperintensity, predominantly in white matter but with some possible gray matter involvement. Mild mass effect is present. Courtesy of Judith Donovan Post, University of Miami School of Medicine.
MRI of PML. Axial proton density image shows scattered areas of hyperintensity, predominantly in white matter but with some possible gray matter involvement. Mild mass effect is present. Courtesy of Judith Donovan Post, University of Miami School of Medicine.
Congenital CMV infection: (a) cerebral section showing microcephaly and ventricular enlargement; (b) low-power view of ependymitis from the same case.
Congenital CMV infection: (a) cerebral section showing microcephaly and ventricular enlargement; (b) low-power view of ependymitis from the same case.
Congenital CMV. Demonstration of CMV antigen in inclusion-bearing cells in subependymal position.
Congenital CMV. Demonstration of CMV antigen in inclusion-bearing cells in subependymal position.
CMV. Ventriculoependymitis with foci of necrosis in nearby dentate nucleus of the cerebellum (arrows). Luxol fast blue-cresyl violet stain.
CMV. Ventriculoependymitis with foci of necrosis in nearby dentate nucleus of the cerebellum (arrows). Luxol fast blue-cresyl violet stain.
MRI of CMV ependymitis. T1-weighted coronal image with contrast demonstrating ependymal enhancement around the third and lateral ventricles. Courtesy of Gordon Sze, Yale University School of Medicine.
MRI of CMV ependymitis. T1-weighted coronal image with contrast demonstrating ependymal enhancement around the third and lateral ventricles. Courtesy of Gordon Sze, Yale University School of Medicine.
Multinucleate giant cell in the hypothalamus from a case of IME. Immunostain with measles antibody is immunopositive in the nuclei. Counterstained with hematoxylin.
Multinucleate giant cell in the hypothalamus from a case of IME. Immunostain with measles antibody is immunopositive in the nuclei. Counterstained with hematoxylin.