Infections

Question 1

Potential spaces in the brain that can be infected

Answer 1

Epidural
Subdural
Subarachnoid
Intraparenchymal
Draining veins/sinuses

Question 2

Abscess

Answer 2

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

Question 3

Empyema

Answer 3

subdural infection
can spread
mass effect, push brain over

Question 4

Meningitis

Answer 4

subarachnoid

Question 5

Encephalitis

Answer 5

diffuse parenchymal infection

Question 6

Brain abscess

Answer 6

parenchymall focal infection

like a brain tumour

Question 7

Septic thrombophlebitis

Answer 7

infected venous clot

Question 8

Hematogenous sources

Answer 8

most agents

Question 9

Contiguous sources

Answer 9

sinus/ear/face

bacterial

Question 10

Direct inoculation

Answer 10

trauma/surgery

bacterial

Question 11

Nervous sources

Answer 11

HSV

VZV

Question 12

CSF studies

Answer 12

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

Question 13

Bacterial meningitis

Answer 13

Life-threatening

change in LOC

Question 14

Bacterial meningitis CSF

Answer 14

+++ WBC
+++ PMN
low glucose

Question 15

Viral meningitis

Answer 15

self-limiting

no change in LOC

Question 16

Meningitis presentation

Answer 16

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

Question 17

viral meningitis CSF

Answer 17

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

Question 18

Fungal meningitis CSF

Answer 18

+/- WBC
+ lymphocytes
normal gluc

Question 19

Bacterial meningitis pathogens

Answer 19

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

Question 20

Pathogenesis of meningitis

Answer 20

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

Question 21

Pia-arachnoiditis SSx

Answer 21

headache
stiff neck
Kernig/Brudzinski signs

Question 22

Subpial encephalopathy ssx

Answer 22

confusion
stupor
coma
convulsions

Question 23

Inflammatory/vascular involvement of CN roots SSx

Answer 23

ocular palsies
facial weakness
deafness

Question 24

Thrombosis of meningeal veins SSx

Answer 24

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

Question 25

Cerebellar/cerebral hemisphere herniation SSx

Answer 25

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

Question 26

Meningitis tx principles

Answer 26

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

Question 27

Meningitis empiric therapy

Answer 27

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

Question 28

Viral meningitis etiology

Answer 28

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

Question 29

Bacterial brain abscess causes

Answer 29

trauma emboli osteomyelitis

Question 30

Parasitic/fungal brain abscess

Answer 30

in immunocompromised

Question 31

Immunocompetent brain abscess agents

Answer 31

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

Question 32

Symptoms of brain abscess

Answer 32

``` headache fever focal neurological deficits mental status changes seizures N/V nuchal rigidity ``` symptoms not acute as meningitis

Question 33

Brain abscess tx

Answer 33

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

Question 34

Subdural empyema overview

Answer 34

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

Question 35

Encephalitis SSx

Answer 35

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

Question 36

Meningitis vs encephalitis

Answer 36

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

Question 37

Viral causes of encephalitis

Answer 37

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

Question 38

Other causes of encephalitis

Answer 38

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

Question 39

Septic thrombophlebitis overview

Answer 39

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