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Flashcards in Infections Deck (39):
1

Potential spaces in the brain that can be infected

Epidural
Subdural
Subarachnoid
Intraparenchymal
Draining veins/sinuses

2

Abscess

epidural infection (enclosed)
tend to be ocal
can present like tumours
could be due to osteomylitis

3

Empyema

subdural infection
can spread
mass effect, push brain over

4

Meningitis

subarachnoid

5

Encephalitis

diffuse parenchymal infection

6

Brain abscess

parenchymall focal infection
like a brain tumour

7

Septic thrombophlebitis

infected venous clot

8

Hematogenous sources

most agents

9

Contiguous sources

sinus/ear/face
bacterial

10

Direct inoculation

trauma/surgery
bacterial

11

Nervous sources

HSV
VZV

12

CSF studies

increased protein: may mean inflammation causing leaky blood vessels
high gluc: usually diabetes
low gluc: fungal/TB
Electrophoresis for protein peaks to identify unusual infections

13

Bacterial meningitis

Life-threatening

change in LOC

14

Bacterial meningitis CSF

+++ WBC
+++ PMN
low glucose

15

Viral meningitis

self-limiting

no change in LOC

16

Meningitis presentation

fever, headache, stiff neck
usually CT --> lumbar puncture
but imaging usually normal

17

viral meningitis CSF

+/- WBC
+ lymphocytes
normal gluc
do PCR for HSV, enterovirus, etc

18

Fungal meningitis CSF

+/- WBC
+ lymphocytes
normal gluc

19

Bacterial meningitis pathogens

Newborn: GBS, E coli, Listeria
Infant: GBS, E coli, Hemophilius
Adult: pneumococcus, meningococcus, haemophilus, listeria, staph

20

Pathogenesis of meningitis

1) Nasopharyngeal colonization
2) Local invasion
3) bacteremia
4) endothelial cell injury --> increased BBB permeability
5) meningeal invasion
6) subarachnoid space inflammation --> increased BBB permeability, cerebral vasculitis, cytotoxic edema, cerebral infarction
7) increased CSF outflow resistance
8) hydrocephalus/interstitial edema
9) increased ICN
10) decreased cerebral blood flow

21

Pia-arachnoiditis SSx

headache
stiff neck
Kernig/Brudzinski signs

22

Subpial encephalopathy ssx

confusion
stupor
coma
convulsions

23

Inflammatory/vascular involvement of CN roots SSx

ocular palsies
facial weakness
deafness

24

Thrombosis of meningeal veins SSx

focal seizures/cerebral defects
e.g. hemiparesis, aphasia
may be a spinal cord infarction

25

Cerebellar/cerebral hemisphere herniation SSx

upper cervical cord comrpession with quadriplegia or
signs of midbrain-third nerve compression

26

Meningitis tx principles

start appropriate abx ASAP
if LP is delayed due to need for CT, obtain blood cultures + start Abx immediately

27

Meningitis empiric therapy

Ceftriaxons 2g iv q12h
+ vancomycin (for penicillin-resistant S pneumoniae)
+/- ampicilin (elderly, immunosuppressed, pregnant)
+/- dexamethasone (prior to/with first dose of Abx)

28

Viral meningitis etiology

enteroviruses - echo/coxsackie
HSV, varicella, HIV, mumps
HSV - medical emergency
consider encephalitis if altered LOC
lymphocytic choriomeningitis
adeno
CMV

29

Bacterial brain abscess causes

trauma
emboli
osteomyelitis

30

Parasitic/fungal brain abscess

in immunocompromised

31

Immunocompetent brain abscess agents

Parasitic: toxoplasma gondii
Fungal: cryptococcus neoformans
Mycobacterial: TB
Polymicrobial bacterial infection:
- strep anginosus
- anaerobes
- staph aureus
- gram negative

32

Symptoms of brain abscess

headache
fever
focal neurological deficits
mental status changes
seizures
N/V
nuchal rigidity

symptoms not acute as meningitis

33

Brain abscess tx

aspiration
empiric antibiotics:
ceftriaxone + metronidazole +/- vanco
OR meropenem +/0 vancomycin
GCs for swelling (dexamethasone)

34

Subdural empyema overview

Bacterial: S aureus
usually due to trauma/surgery/sinus disease
tx with drainage/antibiotics

35

Encephalitis SSx

acute fever
convulsions, delirium, confusion, stupor/coma
aphasia, hemiparesis
involuntary movements, ataxia
myoclonic jerks, nystagmus
could have a meningitis component

36

Meningitis vs encephalitis

Meningitis: intact brain fxn
Encephalitis: abnormal brain fxn - altered mental status, motor/sens deficits, change in behaviour/personality, speech/movement disorder

37

Viral causes of encephalitis

HSV, varicella, EBV
WEE, EEE, West Nile
HIV
Rabies
viral infections cross BBB

38

Other causes of encephalitis

CJD - spongiform encephalopathy
- usually presents more as a dementia rather than acute infection

Prion disease

39

Septic thrombophlebitis overview

bacterial - trauma, surgery, facial infection, sinusitis
Symptoms: headache, obtundation, seizures, venous infarctions