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10.11 Viral Infections of the Brain
1:10 by Dr. Del Valle
26
Microbiology
Professional
10/11/2011

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Term
What is a viral encephalitis?
Definition
a viral infection of the brain parenchyma
Term
What is a viral myelitis?
Definition
a viral infection of the spinal cord
Term
What are the most important viral encephalitises/myelitis/meningitis?
Definition
poliomyelitis, rabies, herpes simplex encephalitis, progressive multifocal leukoencephalopathy, subacute sclerosing panencephalitis, CMV, and AIDS encephalopathy
Term
Which type of poilomyelitis virus is most commonly associated with CNS disesae?
Definition
type 1
Term
Which part of the spinal cord is generally spared by polio?
Definition
cervical and lower sacral regions
Term
What is the most characteristic finding of polio in its early stages?
Definition
perivascular infiltrates of neutrophils (after several days to a week, they arereplaced by lymphocytic infiltrate)
Term
T/F Bats can apparently transmit rabies without themselves being infected.
Definition
true
Term
T/F Even if the animal is infected, it is rare to get rabies following a mouse or guinea pig bite.
Definition
true
Term
What determines the incubation period of rabies?
Definition
the distance from the peripheral nerves at the inital site of infection, and the CNS
Term
Where are the lesions in the first and second form of rabies?
Definition
first form: brainstem and cranial nerve ganglia
second form: cortex and gray matter
Term
What are the characteristic findings of rabies encephalitis?
Definition
1) lymphocytic infiltrates concentrated in the meninges and around parenchymal vessels 2) typical glial nodule 3) negri body- eosinophilic, cytoplasmic inclusion with a basophilic core
Term
Where are the two most common locations for negri bodies?
Definition
hippocampus and purkinje cells in cerebellum
Term
What are the symptoms of herpes encephalitis?
Definition
rapid onset of fever, chills, restlessness, and signs of increased intracranial pressure
Term
What is the mortality rate of herpes encephalitis?
Definition
25%
Term
What is the characteristic gross appearance of herpes encephalitis?
Definition
edema, hemorrhages and necrosis confined primarily to the temporal lobes. Degree of edema= medial displacement of the uncal gyrus. Can be bilateral or unilateral. Can extend into the cingulate gyrus
Term
What are the findings of acute stage versus later stage herpes encephalitis?
Definition
early: vascular destruction with infiltrates of neutrophils and lymphocytes. Later: glial proliferation
Term
What is the histological feature that characterizes herpes simplex encephalitis?
Definition
eosinophilic intranuclear inclusion bodies (Cawdry type A) in neurons, astrocytes, and oligodendroglia. Charactersistic bull's eye apperance
Term
What types of encephalitises can occur secondary to a measles virus?
Definition
1) SSPE 2) acute encephalitis with lymphocytic infiltrate in meninges and around vessels with acute rash of measles 3) post measles demyelinating process, autoimmune hyperallergenic phenomenon
Term
What are the symptoms of subacute sclerosing panencephalitis?
Definition
progressive motor and mental deterioration with myoclonus. 1-3 years
Term
What is the frequency and male:female ratio of SSPE?
Definition
1/1 million
4:1
Term
85% of SSPE arise in ____ environments.
Definition
rural
Term
What is the gross pathology of SSPE?
Definition
atrophy of cortex, loss of white matter, ventricular enlargement.
Term
What are the histological findings of SSPE?
Definition
eosinophilic intranuclear inclusions with features virtually identical to inclusions found in cases of herpes simplex encephalitis (found in neurons, astrocytes and oligodendroglia)
Term
What are the three contexts in which Cytomegalic inclusion disease (CID) is found?
Definition
1) treatment induced immunosuppressed adults 2) neonates with widespread infection 3) intrauterine infection with CMV (3rd trimester)
Term
Infants who survive congenital CMV rae left with...
Definition
microcephaly and mental retardation. Grossly periventricular calcium deposites
Term
What is the characteristic histologic appearance of CMV?
Definition
basophilic intranuclear inclusions in neurons. INclusions also found in the adventitial cells of blood vessels
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