Neuropathology IV Flashcards
(53 cards)
what are the causes of CNS infections?
- Bacteria
- Virus
- Fungus
- Parasite
- Prion
what are the routes of entry for CNS infections?
- hematogenous: arterial blood (most common), retrograde anastomoses of face and sinus veins
- direct implantation: trauma or lumbar puncture (iatrogenic; rare)
- local extension: sinusitis, tooth infection, osteomyelitis
- transport along peripheral nerves: rabies, herpes
what are the common bacterial causes of Acute Pyogenic Meningitis in neonates?
Group B Streptococcus
E coli
Listeria Monocytogenes
what are the common bacterial causes of Acute Pyogenic Meningitis in children?
- Neisseria meningitidis ( Associated with Waterhouse-Friedrichsen Syndrome)
- Streptococcus pneumoniae
- Haemophilus Influenzae ( Virtually eliminated due to vaccination)
what are the common bacterial causes of Acute Pyogenic Meningitis in elderly?
Streptococcus pneumoniae
Neisseria meningitidis
E coli
Staph Aureus
Which organisms are commonly associated with meningitis in patients with shunt infections?
Staphylococcus epidermidis and Staphylococcus aureus.
Which organisms commonly cause bacterial meningitis after neurosurgery?
Staphylococcus aureus and Staphylococcus epidermidis
What are the typical organisms causing meningitis in patients with a skull fracture?
Streptococcus pneumoniae and Haemophilus influenzae
what are the clinical features of APM?
Headache
Nuchal rigidity
Clouding of consciousness
Fever (can be absent in up to 50% of cases)
Irritability
how does the CSF change in a patient with acute pyogenic meningitis?
Pleocytosis (neutrophils)
High protein
Low glucose
Bacteria on smear or culture
what are the common viruses that cause acute viral meningitis?
Enterovirus
HSV-2
WNV
What are the typical clinical features of acute viral meningitis?
Symptoms are similar to bacterial meningitis but usually less severe (less fulminant)
What are the typical cerebrospinal fluid (CSF) findings in acute viral meningitis?
- Pleocytosis (mainly lymphocytes)
- Slightly elevated protein
- Normal glucose
- Viral culture or PCR positive
What are the common infectious causes of chronic meningitis?
M. tuberculosis
Cryptococcus
Histoplasma
Coccidioides immitis
Syphilis
What are the characteristic features of CNS tuberculosis (tuberculous meningitis)?
Gross pathology: Greyish, gelatinous, viscous exudate at the base of the brain
CSF findings: Elevated protein, low glucose
What is the most common cause of fungal meningitis, especially in immunocompromised patients?
Cryptococcus neoformans, often acquired from pigeon droppings.
What are the characteristic histologic findings in cryptococcal meningitis?
“Soap bubble” cysts in the brain parenchyma
How is Cryptococcus neoformans visualized in the lab?
Budding yeast seen with India ink or mucicarmine staining
What is the most common cause of a brain abscess?
bacterial infections through direct implantation, local extension (e.g. mastoiditis), and hematogenous spread
What predisposing conditions can lead to brain abscesses via hematogenous spread?
Acute bacterial endocarditis and chronic pulmonary infections (e.g. bronchiectasis)
How might a brain abscess appear on imaging and what condition can it mimic?
As a ring-enhancing lesion, mimicking a brain tumor
What is the typical pathological appearance of a brain abscess?
A discrete destructive lesion with central necrosis surrounded by granulation/fibrous tissue
What symptoms are typically seen with brain abscess due to increased intracranial pressure?
Progressive focal neurological deficits and general signs like headache, nausea, and vomiting and very high mortality rate
What is the preferred specimen for microbiological diagnosis in brain abscess and what is the treatment?
Direct culture of the drained abscess (not CSF)
Surgery plus antibiotics