Pathology and pathogenesis of encephalitis

Macroscopic signs of encephalitis (hyperemia, minor bleeding, swelling of the brain) in diagnostic attitude is not important. The diagnosis of encephalitis is secure only after histological study of many parts of the brain, because the topic defeat at different encephalitis is not the same.
Microscopic diagnosis of encephalitis is based on: 1) inflammatory (lymphocytic, plasmacleaner, neutrophil, macrophage, mixed) infiltrates around vessels; 2) the proliferation of the cells of the vascular wall; 3) diffuse proliferative response micro - and oligodendroglia, often with the formation of rod-shaped cells and amoeboid faguoqitirute elements; 4) establishment of microglial outlets and star-shaped structures, as well as microgranules around vessels (for example, when typhus) or nevrologicheskij knots around the dead cells (for example, rabies, polio, tick-borne encephalitis). Syncytial microglial proliferate in a molecular layer of the cerebellum less typical and can be found in non-inflammatory lesions of the Central nervous system (e.g. encephalopathy, complicating severe typhoid fever). In some infections (tuberculosis, syphilis, brucellosis) encephalitis may be accompanied by the emergence of larger granulomas with necrotic centers.
The number of encephalitis is characterized by the formation of specific inclusions in nerve cells (for example, bullock Negri when rabies) or outside them. Intranuclear inclusions typical for herpes encephalitis. Intra - and extracellular enable found in the so-called inclusional encephalitis Dawson, subacute sclerosing leukoencephalitis van Bogart and so on, Great diagnostic value has presence in the Central nervous system of infectious agents.
In the pathogenesis of many encephalitis, in addition to the direct actions of agents of infection in the tissue of the brain have some value and allergic reactions, the value of which, apparently, is especially great for chronic and subacute forms of encephalitis.
Histopathological different picture encephalitis significantly varies depending on the stage of the disease. During acute encephalitis is dominated by circulatory disorders and exudative reaction, perivascular infiltrates, nevrologicheskoe processes. When more protracted the period of infiltrates disappear and come to the fore proliferative effects (including the proliferation of astrocytes), the emergence of hotbeds of destruction of nerve tissue, which can take either a spongy nature, or be accompanied by accumulation grainy balls. Chronic forms of encephalitis lead to fibrillar the gliosis and demyelination, and sometimes atrophic changes in certain parts of the brain.
Some forms of encephalitis occur with the acute alteration of nerve tissue that is to treat them as "acute necrotizing" encephalitis [Grune (J. E. Gruner) and others] with sometimes severe hemorrhagic component [Bellucci (C. Berlucchi)]. The number of cases of acute necrotizing" encephalitis currently has increased significantly in many countries. It can be accompanied by the formation of intracellular inclusions.
Authentic cases of so-called borne encephalitis in which of the brain tissue would have been able to highlight the influenza virus is unknown. Rare inflammatory brain damage after a recent myocardial flu most likely belong to the activation of other nairovirus, such as herpes virus that has convincingly shown Cabin (A. Sabin).
Postvaccinal encephalitis after the use of smallpox vaccine and measles characterized periodogram distribution infiltrates with subsequent demyelination mainly in the white matter of the big hemispheres of a brain and presumably refers to allergic lesions of the Central nervous system.