2: CNS Infections Flashcards
4 main routes of CNS infection
- hematogenous: MC
- direct implantation from trauma
- local extension: sinuses, teeth, cranial osteomyelitis
- PNS (rabies, herpes)
how often does a complete exchange of CSF occur?
every 3-4hrs
how does cerebral edema occur in terms of infection?
infection -> loss of cap integrity -> loss of BBB -> intravascular fluid enters brain/SC
what drug can slow and reverse cerebral edema caused by infection?
corticosteroids
ventriculitis with meningitits
fulminant meningitis can extend inflammation into the ventricles
focal cerebritis
inflammatory cells infiltrate walls of the veins and extend in the brain surface
if CSF shows gram neg diplococci…
N. meningitidis
if CSF shows gram pos diplococci…
S. pneumoniae
if CSF shows gram neg pleomorphic cells…
H. influenzae
if CSF shows gram positive cocci…
S. aureus or S. epidermitis
if CSF shows gram neg bacilli…
E. coli or other gram neg
N. meningitidis meningitis sx
septicemia, fever, hypotension, DIC, petechial and purpuric lesions (purpura fulminans), can turn into gangrene, Waterhouse-Friderichsen syndrome (adrenal gland hemorrhagic infarct)
why is it important to get a culture in addition to a smear in chronic meningitis?
CSF smear is positive in 10-20% of cases, but CSF culture is positive in 40-90%
lymphatics in the head
none in CSF, but lymphatics are present in the epidural space
four protozoal CNS infections
malaria toxoplasmosis, amebisis, trypanosmiasis
