Flashcards in CNS Infections Deck (77)
What can an untreated CNS infection cause?
Brain herniation and death
Cord compression and necrosis with subsequent permanent paralysis
What does the gross morphology of pyogenic (bacterial) meningitis show?
Thick layer of suppurative exudate covering the leptomeninges over the surface of the brain
Exudate in basal and convexity surface
What does pyogenic meningitis show microscopically?
Neutrophils in the SA space
What is the DDx for fever and altered mental status?
Severe sepsis syndrome due to infection elsewhere
When does viral meningitis usually present?
What causes viral meningitis?
Enteroviruses e.g. ECHO virus
Other microbes and non-infectious causes also
How is viral meningitis diagnosed?
Viral stool culture, throat swab and CSF PCR
What is the treatment for viral meningitis?
Supportive as self-limiting
What viruses can cause viral encephalitis?
What is the treatment of HSV encephalitis?
Aciclovir IV high doses- must be recognised, admitted and treated within 6 hours
What is the history and treatment of VZV encephalitis?
History of shingles
High dose acyclovir
What are the travel related causes of viral encephalitis?
West Nile, Japanese B encephalitis, Tick Borne encephalitis
What are the occupational related causes of viral encephalitis?
What are the non-infectious causes of viral encephalitis?
What are the clinical features of encephalitis?
Insidious onset-sometimes sudden
Seizures, partial paralysis
Speech, memory symptoms
What investigations are required in viral encephalitis?
If there is a delay in investigations in suspected viral encephalitis what should be done?
Start pre-emptive acyclovir as prompt therapy improves outcome
What are the MRI findings in encephalitis?
Inflamed portion of the temporal lobe, involving the uncus and adjacent parahippocampa I gyrus (brightest white on MR)
What are the common causes of bacterial meningitis related to age?
Neonates: listeria, group B streptococci, E. coli
Children: H. influenza
10 to 21: meningococcal
21 onward: pneumococcal >meningococcal
What are the common causes of bacterial meningitis related to RFs?
Decreased CMI: listeria
S/P neurosurgery or opened head trauma: Staphylococcus, Gram Negative Rods
Fracture of the cribiform plate: pneumococcal
What is the likely causative organism in bacterial meningitis due to an immunocompromised state?
aerobic GNR (including Ps.aeruginosa)
What is the likely causative organism in bacterial meningitis due to a basilar skull fracture?
beta-hemolytic strep group A.
What is the likely causative organism in bacterial meningitis due to head trauma or post-neurosurgery?
What is the likely causative organism in bacterial meningitis due to a CSF shunt?
What can be some long term effects of meningitis and septicaemia?
Severe mental impairment
What is the pathogenesis of bacterial meningitis?
1. Nasopharyngeal colonisation
2.Direct extension of bacteria: parameningeal foci (sinusitis, mastoiditis, or brain abscess), across skull defects
3. From remote foci of infection: (e.g. endocarditis, pneumonia, UTI etc)
What are some agents of meningitis in immunocompromised patients?
Conventional agents- s.pneumonia, s.aureus etc
Cryptococcus neoformans (AIDS)
What does Neisseria meningitides cause?
What are the symptoms in meningococcal meningitis due to?
Endotoxin from bacteria