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Medicine II: Infectious Disease > CNS Infections > Flashcards

Flashcards in CNS Infections Deck (28):
1

Blood Brain Barrier

tight junctions linking endothelial cells of vessels in the brain. This protects the CNS from invading pathogens or toxic substances. (the limiter permeability acts as a barrier). It also prevents entry of immunoglobulins, compliment and abx. Thus if a pathogen gets here there is rapid progression.

2

Pathogens of Community Acquire Bacterial Meningitis

streptococcus pneumoniae, neisseria meningitidis, listeria monocytogenes, H. influenza

3

What does s. pneumoniae infect?

ears, sinus, lungs and spreads to blood stream

4

What does n. meningitidis infect?

isolated sporadic infection or epidemic, attacks nasopharynx -> sore throat

5

What does listeria monocytogenes infect?

attacks the weak, youmg, or prego (GI mediated)- food

6

Primary sites of infection leading to bacterial meningitis

most commonly blood borne, primary infections of the ears, sinuses, throat, lungs, heart and GI tract via basilar skull fracture

7

CSF findings that indicate bacterial meningitis

increased WBC (more than 90% PMNs)- PMNs increase at site as organism proliferates; lyse and lead to tissue necrosis- Hypoglycorrachia (low glucose)-due to inflammation of arachnoid and pia matter, Rise in protein- due to leakage of serum from damaged vessicles, Increased ICP

8

Indications for LP

no focal neurological deficits are present and no papillodema, no AIDS patients on immunosuppressants- higher frequency of cortical space occupying lesions

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What do you do if you cant get and LP?

send for CT, get a blood culture and treat

10

T/F: Gram stain is 75% gram pos for bacterial meningitis

True

11

Tx for bacterial meningitis

tx with in 30 min, maximal dose abx b/c of limited passage through BBB. Give dexamethasone before abx to prevent neurological damage.-------------------------------------------------------------------------If 3mo-60yr give ceftriaxone or cefotaxime (3rd gen ceph), if severely ill give vancomycin, in >60yo or immunocomprimised give ceftriaxone/ceftotaxime PLUS ampicillin PLUS vancomycin. If nosocomial give vancomycin PLUS ceftazidime/cefepime

12

Etiologies for Viral Meningitis

enteroviruses, echinoviruses and coxsackie viruses

13

Clinical manifestations of viral meningitis

headache, stiff neck, photophobia, conjunctivitis, rash

14

Dx of viral meningitis

CSF: increased lymphocytes, normal glucose, mild protein increase. PCR can make dx of HSV and enterovirus

15

Tx of Viral meningitis

supportive care: adequate hydration, antipyretics, antiemetics, analgesia (for headaches). IF HSV use antiviral therapy AND supportive (IV acyclovir)

16

Cryptococcal Meningitis

organism is inhaled, high concentrations of yeast like fungus in pidgeon droppings. Thick capsule that is immunosuppressive. Produces melatonin and manitol which increase virulence and increase cerebral edema.

17

Symptoms of Cryptococcal Meningitis

Severe intermittent headache is most common symptom. Also personality changes, stupor/coma. More common in immunosuppressed patients (AIDS). Can have occular motor palsies and hearing loss (decreased visual acuity and diploplia)

18

Dx of Cryptococcal Meningitis

LP: WBC 20-200 (predominance of mononuclear cells), mild protein elevation, moderate decrease in glucose. Mix 1:1 with india ink to see encapsulated particles. CT and MRI show discrete cryptococcomas

19

Aseptic meningitis (signs and symptoms)

headache, neck stiffness, photophobia, nausea during primary HIV infection

20

Lab findings for asceptic meningitis

moderate to no immunosupression; moderate rise in CSF count

21

Tx for asceptic meningitis

no specific tx, spontaneously resolves

22

Encephalitis

3 major categories: mosquito borne (arbovirus), animal to human (rabies), human to human (herpes)

23

Symptoms of encephalitis

hallucinations, seizures, ataxia (w/rabies ascending paralysis, rapid short respirations, possibly RBCs)

24

Dx of encephalitis

CSF: WBC below 500, mild increase in protein, possibly RBCs. May need brain biopsy to dx

25

Tx of encephalitis

acyclovir

26

Brain Abscess

symptoms initially nonspecific and delay in dx is common. Severe head ache at point of abscess. Alterations in mental status and neck stiffness. Vomiting and INCREASED ICP. Can be caused via direct ear infection, dental infection or frontal sinus.

27

Dx of brain abscess

MRI not CSF

28

Tx of Brain abscess

PCN or metronidazole