CNS infections Flashcards
Time course = diffuse and acute
meningitis (bacterial) or toxic/metabolic cause
Time course = focal and subacute
brain abscess, spinal abscess, venous vascular, trauma
Time course = diffuse and subacute
meningitis (bacterial or viral), encephalitis, AI, T/M
Time course = focal and chronic
brain abscess or tumor
Three major locations of the BBB:
1) arachnoid epithelium
2) meninges surface
3) choroid plexus
The medications which can cross the BBB ONLY in the presence of inflammation include:
penicillins
3/4th gen cephalosporins
vanco
Pathogens that cause CNS infections:
1) encapsulated organisms (N. meningitidis, S. pneumoniae, H. influenzae, C. neoformans)
2) intracellular organisms (L.monocytogenes, enterovirus or arbovirus)
3) if trauma = normal flora of site
4) some organisms if systemic (S. aureus, GBS, TB, HIV)
(3) DO NOT MISS findings on PE
1) meningeal irritation
2) intracranial HTN signs
3) focal neurologic sign
The single most important diagnostic test for Meningitis_____?
the lumbar puncture, but not if contraindications!
(4) Contraindications for LP:
1) intracranial mass lesion
2) intracranial HTN
3) severe thrombocytopenia or coagulopathy
4) agitated pt.
(T/F) Attempts to safely perform LP should NEVER delay the administration of Abx for possible bacterial meningitis.
TRUE!!!
-start empiric treatment and don’t forget the blood culture!
classic triad of sxs for meningitis
fever, nuchal rigidity, altered mental status (most have 2/3)
-also HA and vomiting
Ways in which neonatal meningitis is different from non-neonatal?
- clinically indistinguishable from other sepsis syndromes
- must be considered in any febrile illness of a newborn
CSF findings in bacterial meningitis
WBC: 1000-5000
primary cell: PMN
Glucose:
How do I treat meningitis?
most often: vanco + 3rd gen cephalosporin
+ adjunctive steroid therapy to suppress inflammation (S. pneumoniae, H. influenzae, TB)
(T/F) The most common etiology of encephalitis is bacteria?
False! >80% is idiopathic, otherwise is viral (HSV, VZV)
HSV Encephalitis
treatable!
- involves the temporal lobe
- sxs: fever and personality change, also: seizure, aphagia, motor deficit
Gold standard for HSV encephalitis diagnosis =
HSV PCR on CSF
-CSF will also often show elevated RBCs, but may also be normal
How do I treat HSV encephalitis?
Acyclovir at a high dose!
- should be started immediately if suspected, do not wait for results.
- consider HSV in all pts w/ encephalitis
(3) pathogenesis of the signs and sxs of meningitis:
1) inflammation (of meninges and surrounding tissue)
2) increase intracranial pressue
3) direct injury to nerve tissues
