Micro: Greenberg 1 Flashcards
What part of the CNS rarely gets infected?
spinal cord itself - but spaces around it do
What are the three possible categories of infections within the calvarium?
meningitis - symptoms of meningeal inflammation
encephalitis - requires evidence of cerebral dysfunction = parenchymal inflammation
meningoencephalitis - usually see the meningitis first
What kinds of abscesses are seen in infections?
epidural > subdural
What are some non-infectious causes of meningitis?
neoplastic conditions chemical meningitis (IVIG)
What are the two most common causes of infectious meningitis in the US?
bacterial and viral
What is the classic presentation of infectious meningitis?
triad of fever, headache, stiff neck - but can’t rely on this presentation to screen - only 44% of pts actually have triad
How is meningitis diagnosed?
most important test is CSF analysis
obtaining cultures critical - need CSF before antibiotics
What are some things to consider when testing CSF and cultures for treating meningitis?
LP has risks (herniation)
Cultures needed early - if you wait or give antibiotics first, the CSF changes and you don’t know if you’re treating correctly
biggest factor is time to first antibiotics but testing can take time
Why are steroids given before empiric antibiotics when treating meningitis?
reduce morbidity not mortality
most common sequelae = hearing loss - admin of steroids lessens inflammation that occurs after lysis of encapsulated organisms (secondary inflammation is thought to cause damage to CNS and CNs) = why pts get worse before better
What is the difference between bacterial and viral meningitis?
viral requires only supportive care - assume bacterial til proven otherwise
no clinical ways to differentiate
What causes the majority of infectious encephalitides?
viruses: arbovirus (west nile), HSV = most common cause of sporadic viral, enteroviruses
What are acute complications of bacterial meningitis?
edema and herniation, hydrocephalus, SIADH or CW, sepsis, multiorgan failure
What is partially treated meningitis?
give viral treatment but it is actually bacterial - LP later won’t be accurate because incorrect treatment has caused CSF to look like viral - BAD
What are important conclusions found about viral encephalitis?
lots of viral and non-infectious encephalitis pts have NO WBCs in CSF
2/3 of pts never obtain dx - hard to figure out causative agent
What are the three broad causes of encephalitis?
infectious, toxin, immune mediated post-infectious/autoimmune
