10 Neuropathology (CNS infections) Flashcards
Name the 4 routes via which infectious agents can enter the CNS
- hematogenous
- direct implantation
- local extension from adjacent site of infection
- axoplasmic transport along peripheral nerve axons
Bacteria and yeast most often cause what type of meningitis?
pyogenic or granulomatous
Hyphal forms of fungi most often cause ____ and _____
cerebritis
abscesses
T/F- bacterial is the most common type of CNS infection and results in meningitis more frequently than abscess
true
Viral infections usually cause what?
encephalitis, meningoencephalitis
Describe the CSF findings in bacterial pyogenic meningitis
many neutrophils
high protein
low glucose
Describe the clinical symptoms of bacterial pyogenic meningitis
headache
altered mental state-encephalopathy
increased intracranial pressure
seizures
What 2 organisms cause acute (purulent) meningitis in neonates
Group B strep
Listeria Monocytogenes
What 3 organisms cause acute meningitis in young children
N. meningitidis
Strep pneumoniae
H. influenzae (unvaccinated)
What 2 organisms cause acute meningitis in older children/adults?
Strep. pneumoniae
Neisseria meningitidis
T/F- in bacterial meningitis you’ll likely see pmns in leptomeninges
true
Name 2 complications of meningitis
infarcts
chronic hydrocephalus
Lymphocytic meningitis (aka aseptic/viral) is usually self limited. What will you see in the CSF?
lymphocytes
moderately high protein
Normal glucose
Name 2 most common causes of lymphocytic/aseptic meningitis
echovirus
coxsackie virus
Name 3 causes of chronic (granulomatous) meningitis
- M. tuberculosis/avium
- Yeast forms of fungi (cryptococcus, coccidioides, blastomyces)
- rarely sarcoidosis
What is a feared complication of chronic meningitis?
obliterative endarteritis leading to infarction of underlying brain
chronic meningitis has a predilection for _____
base of brain
What bacteria commonly cause cerebrates and abscess in the brain?
Anaerobic strep
Strep pneumoniae
Staph sp.
What fungi cause cerebrates and abscess of the brain?
aspergillus
mucor
candida
What protozoal infection can cause cerebrates and abscess of the brain?
toxoplasma
What is the most common method of pathogen “spread” leading to cerebritis and abscess?
Direct spread (50%) hematogenous spread (25%)
Rank the following from most to least common location of brain abscess: parietal, cerebellum, frontal
Frontal»parietal>cerebellum
What is cerebritis?
focal infection/inflammation before an established abscess (with a wall) forms
T/F- abscesses present as a ring enhancing lesion on CT
true
What type of pathogen (virus, bacteria, etc) is most often responsible for encephalitis?
viruses
Will you see microglial nodules and neuronophagia with viral encephalitis?
yes
Rabies: ____ body inclusion
Herpes: ____ body inclusion
negri body
cowdry type A
What virus causes progressive multifocal leukoencephalopathy?
JC virus
In HIV encephalitis, you’ll often see multinucleated giant cells located where?
around vessels
in PML you’ll see bizarre, atypical ______ as well as intranuclear inclusions in ______ cells
- astrocytes (reactive, not neoplastic)
2. oligodendroglial cells
Is toxoplasmosis a ring enchancing lesion?
yes
In spongioform encephalopathy are the vacuoles in the white or gray matter?
gray
Classic triad of symptoms in prion diseases?
rapid dementia
myoclonus
periodic short wave activity on EEG
Are most cases of CJD sporadic or familial?
most are sporadic
only 10-15% familial
What chromosome is the normal gene for protease resistant prion protein on?
chrom20
Describe the pathogenesis of prion disease
- Disease occurs with conformational change of PrP 3D structure into ß-pleated sheet
- Single pathogenic PrP can induce further protein conversions of wild type protein creating a chain reaction
- PrP accumulates in and outside of cells in the form of amyloid
Is there a mutation that increase your risk for sporadic CJD?
Homozygosity for Met or Val at codon 129 increases risk of sporadic CJD
T/F- CJD brain will always show atrophy
false, may look normal or may show atrophy
Describe the microscopic appearance of CJD
Neuronal loss, gliosis, and spongiform change (often patchy), defined by small “punched out” vacuoles in gray matter (cortex ± deep nuclei)
