CNS Infections

Question 1

what is encephalitis

Answer 1

infection of the brain parenchyma

Question 2

what is meningitis

Answer 2

infection of the meninges around the brain

Question 3

what is acute aseptic meningitis

Answer 3

a meningitis infection where the cause is not bacterial (pyogenic) usually viral instead

Question 4

how does pyogenic meningitis present

Answer 4

exudate in basal and convexity surface

Question 5

list the early features of meningitis

Answer 5

headache
fever 
leg pains 
cold feet 
abnormal skin colour

Question 6

list the late features of meningitis

Answer 6

neck stiffness, photophobia - meningism
reduced GCS
seizures and focal CNS signs
shock - prolonged cap refill

Question 7

list the 2 most common causative organisms for meningitis

Answer 7

strep pneumonia
neisseria meningitidis
gram positive and gram negative respectively

Question 8

immunocompromised, older patients and alcoholics are more likely to develop meningitis from which organisms

Answer 8

listeria monocytogenes

haemophilus influenzae

Question 9

what is the treatment for a common community acquired bacterial meningitis

Answer 9

ceftriaxone IV 2g BD

dexamethasone IV 10mg QDS

Question 10

why is dexamethasone prescribed in meningitis

Answer 10

has an anti-inflammatory effect, reduces swelling in the brain which prevents secondary complications such as oedema and raised ICP

Question 11

what antibiotic is given first line for meningitis if someone is penicillin allergic

Answer 11

chloramphenicol

Question 12

what viruses are most likely to cause viral meningitis

Answer 12

ECHO virus

Question 13

what is the treatment for viral meningitis

Answer 13

supportive treatment as condition is usually self-limiting

Question 14

describe the symptoms of encephalitis

Answer 14

changes to mental state 
confusion 
focal neurological signs 
meningism 
fever 
psychosis

Question 15

if a neonate develops meningitis what bacterium are most likely to cause it

Answer 15

listeria
group B strep
E. Coli

Question 16

if a child develops meningitis what bacterium are most likely to cause it

Answer 16

haemophilus influenzae - usually eradicated by vaccine

Question 17

most likely causative organism for meningitis in adults

Answer 17

strep pneumoniae

Question 18

most likely causative organism for meningitis in patient with head trauma

Answer 18

staph

gram -ve bacilli

Question 19

list the main complications of meningitis

Answer 19

exudate forming around cranial nerves III and VI
oedema
ventriculitis
hydrocephalus

Question 20

list the most likely routes of entry for bacterial meningitis

Answer 20

nasopharyngeal colonisation
direct extension from bacterial infection eg sinusitis or mastoiditis
remote foci and spread through blood - endocarditis §

Question 21

when is a lumbar puncture contraindicated in patient with meningitis

Answer 21

when there is risk of raised ICP

elderly patient also

Question 22

list signs of raised ICP

Answer 22

vomiting and nausea 
papilloedema 
headache 
confusion 
pupils do no dilate 
hypertension

Question 23

list the components of the 4 samples that are sent off containing CSF

Answer 23

1 - haematology cell count, differential
2 - microbiology, gram stain, cultures
3 - chemistry, protein and glucose
4 - haematology, cell count, differential

Question 24

list the components of CSF in bacterial meningitis

Answer 24

WCC raised predominately neutrophils
appears cloudy and turbid
glucose low
protein elevated

Question 25

list the CSF findings of a normal sample

Answer 25

WBC 0-5 (primarily lymphocytes, no neutrophils)
RBC 0-10
protein <1% serum
glucose >60% plasma glucose concentration

Question 26

list the components of CSF in aseptic meningitis

Answer 26

WBC slightly elevated predominately lymphocytes
glucose normal
protein slightly elevated
sample appears clear

Question 27

what is the treatment for aseptic meningitis that is HSV positive

Answer 27

IV aciclovir

Question 28

list the occasions where CT is the first investigation before lumbar puncture in the event of suspected meningitis

Answer 28

immunocompromised patient 
history of CNS disease 
new onset seizure 
papilloedema 
focal neurological deficit eg non-reactive pupil, abnormal visual field

Question 29

all adults with suspected meningitis should receive a lumbar puncture in hospital true/false

Answer 29

false - all should get in unless a clear contraindication or confident enough based off of meningococcal rash

Question 30

what antibiotic is added into the prophylaxis if an elderly person has suspected meningitis

Answer 30

amoxicillin - to cover for listeria