5/6 Brain Infections (Ch 26) Flashcards Preview

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Flashcards in 5/6 Brain Infections (Ch 26) Deck (37)
1

what are the 4 cardinal manifestations of brain inflammation?

-fever

-headache

-altered mental status

-focal neuro signs

2

Define meningitis

-inflammation of the membranes of the brain or spinal cord.

-infection involving the subarachnoid and Virchow-Robin spaces (perivascular canals) over the surface of the brain

3

Define encephalitis

inflammation of the brain parenchyma

inside your brain, yo.

4

define myelitis

inflammation of the spinal cord

5

define encephalopathy

disorders/diseases of the brain that include non-infectious causes

6

why is the brain particularly vulnerable to poor outcomes from infection?

-brain has a narrow array of host defenses, and the BBB keeps usual defenses (antibodies, complement) from entering the brain space.

-limited drug penetration into CNS

-brain swelling -> further damage given the space constraints

7

Acute meningitis:

2 examples?

major symptoms?

Bacterial example: Meningococcus.

Aseptic example: Enterovirus

s/s: fever, headache, nuchal rigidity

8

Chronic meningitis: example? symptoms?

Ex: cryptococcus

can be asymptomatic or insidious

9

Acute encephalitis - hematogenous:

example? symptoms?

Ex: west nile virus

s/s: fever, ha, altered mental status

10

Acute encephalitis- neuronal

2 examples? symptoms?

Herpes simplex, Rabies

s/s: fever, ha, altered mental status

11

Chronic encephalitis: example? symptoms?

ex: syphilis

s/s: sensory changes, ataxia, dementia

12

Space occupying lesions:

2 examples?

symptoms for each?

-Brain abscess --> fever, ha, confusion, hemiparesis

-Epidural abscess --> fever, back pain, loss of leg strength/rectal tone/urinary continence

13

Toxin-mediated syndromes: 2 examples? s/s?

-Clostridium tetani (tetanus) --> NO FEVER, spastic paralysis

-Clostridium botulinum (botulism) --> NO FEVER, respiratory paralysis, cranial nerve paralysis

 

14

three causes of encephalitis?

what is their relative mortality?

-Arboviruses (fatal: 1-50%)

-Herpes simplex viruses (fatal: 70% untreated; 10% treated)

-Rabies (fatal: 99% without early PEP)

15

Clinical features of encephalitis? (laundry list)

Acute febrile illness with ha, altered mental status, focal neuro signs +/-

-behavior change, disorientation

-speech issues

-seizures

-motor weakness

-hyper-reflexia

-tremor

-pituitary involvement (hypothermia, diabetes insipidus, SIADH)

-myelitis (flaccid paralysis, bladder/bowel dysfxn, loss of deep tendon reflexes)

-raised intracranial pressure

16

Route of acquisition of viral encephalitis?

HSV and Rabies are acquired via neuronal transmission

Arboviruses (West Nile) are acquired hematogenously

17

Arboviral encephalitis: what are the most common mosquito-borne viruses in the US?

what animals are involved in their lifecycle?

West Nile Virus, Western equine, California encephalitis, St Louis encephalitis, Eastern equine encephalitis

Life cycle: host (birds) and vector (mosquitoes). humans and horses are accidental hosts: mosq bite -> viremia

18

West Nile Virus: 

Clinical features?

-Pt will be ill 3-14 days after mosquito bite

-Most will get West Nile fever: fatigue, fever, ha, muscle weakness, rash (in half)

-Neuroinvasive disease (rare): encephalitis is most common.

19

West Nile: how to diagnose?

-Serology: PCR

-CSF: lymphocytic pleocytosis (=migraine + elevated WBCs), elevated protein; may see CSF antibody

-Imaging is often normal

-EEG may show general slowing

20

West Nile: treatment? prevention?

Treatment is supportive

Prevention: mosquito control and repellants

21

Herpes Simplex encephalitis: three possible routes for CNS infection?

These occur equally: 

-Primary infection via oropharynx, via trigeminal nerve or olfactory tract. (generally in pts <18y)

-CNS invasion after recurrent HSV1 infection, viral reactivation with subsequent spread

-presumed reactivation of latent HSV in situ within CNS

22

Presentation of HSV1 encephalitis v HSV2 encephalitis?

HSV1: localized inflammation 

HSV2: can be more generalised

23

HSV encephalitis: clinical features?

altered level of consciousness (96%)

fever (89%)

ha (78%)

personality change (61%)

seizures (38%)

24

Herpes simplex encephalitis: how to diagnose?

-CSF: high opening pressure, incr WBCs, many RBCs, glucose normal, raised protein

-PCR: pretty good sensitivity and specificity

-EEG

-MRI

-Biopsy

 

25

Herpes simplex encephalitis: treatment?

high dose IV acyclovir

26

Rabies: what is the reservoir? how is it transmitted?

Reservoir = mammals (wild animals: raccoons, skunks, foxes, dogs, bats)

transmitted via saliva

animal rabies is the major reservoir for human infection

most animals with rabies develop acute fatal encephalitis

 

27

Rabies transmission to humans: what % of bites transmit rabies?

more rare types of transmissions?

-5-80% of bites result in transmission (ie we have no effing clue what this number is. presumably this accounts only for bites by a rabid animal but not specified)

-rarer transmission via animal scratches, mucous membrane exposures [omg how would that occur], unwitnessed bat bites, corneal transplant, lab accidents. 

28

Rabies pathophys? how does it reach CNS?

-virus replicates in the muscle cells at the wound site.

-virus taken up by peripheral nerves, transported to CNS at rate of 8-20 mm/day

-serum antibody develops in 10 days (but cannot reach intraneural virus)

 

29

Rabies: incubation time from exposure to clinical disease?

Depends on inoculation distance from the CNS. Symptoms occur when virus reaches the spinal cord.

30

Rabies: two types of presentations? description of each?

1. 80% of cases: "furious" encephalitic rabies. agitation, hydrophobia, salivation, arrythmias, coma, seiz, death

2. 20%: Paralytic/dumb rabies: ascending paralysis, weakness, meningeal signs. 

31

Rabies prevention?

-animal vaccination

-basic wound care for animal bites

-human vaccination (vets, travelers to highly endemic areas)

-post-exposure prophy with rabies vaccine and immunoglobulin

32

Post-infectious encephalomyelitis: define.

 

Post-infectious encephalomyelitis aka acute demyelinating encephalomyelitis (ADEM)

-autoimmune demyelinating disease, looks like acute viral encephalitis.

-may also have rash, fever, resp issues, GI illness.

-more common in children than adults

33

Post-infectious encephalomyelitis: findings on CSF or MRI?

-CSF: normal/nonspecific

-MRI: enhancing multifocal white matter disease c/w (consistent with??) demyelination

34

what are the 2 main "space-occupying lesions" in the brain?

Brain abscess, malignancy

35

Brain abscess: pathophys?

-local extension of an existing infection

-hematogenous spread

36

Bacterial brain abscess: risk factors?

otitis media

mastoiditis

sinusoiditis

dental sepsis

penetrating trauma

congenital heart disease

bacterial lung inf

bacterial endocarditis

immunocompromised patients

37

Diagnosis of space occuping lesions? (ie brain abscess, malignancy)

-Imaging = critical

-Drainage, tissue diagnosis, culture -> antibiotic

-Empiric therapy for presumed bacterial abscess: "Vanco/ceftriaxone/metronidazole directed at mouth, URI, bacteremia pathogens"

-If HIV: empiric treatment for toxoplasma