CNS Infections and Meningitis

Question 1

What are the main routes of pathogen entry into the CNS

Answer 1

haematogenous (most common)
direct implantation (trauma)
local extension (eg from ear)
PNS -> CNS

Question 2

give a pathogen that gets into the CNS via the PNS

Answer 2

rabies

Question 3

what is the classical presentation of meningitis

Answer 3

fever, headache, neck stiffness, disturbance of brain function

Question 4

what are the 3 main causes of acute meningitis

Answer 4

neisseria meningitis
haemophillus influenza
strep pneumonia

Question 5

what are the 2 main causes of chronic meningitis

Answer 5

bac - TB

fungal - cryptococcus neoformans

Question 6

most common cause of encephalitis in UK

Answer 6

HSV1

Question 7

most common cause of encephalitis worldwide

Answer 7

west nile virus

Question 8

how will encephalitis present

Answer 8

inflam of brain perenchyma

-> confusion and disruption of brain function

Question 9

what are the 4 components of septicaemia

Answer 9

capillary leak -> hypovolaemia
coagulopathy -> bleeding and thrombosis
metabolic derangement (acidosis)
myocardial/ multi organ failure

Question 10

what causes aseptic meningitis

Answer 10

caused by viruses (no pus)

coxsakie group B, echoviruses

Question 11

who gets aseptic meningitis and how will it progress

Answer 11

self limiting inf that normally affects <1y olds

Question 12

what is the most common cause of brain abscesses

Answer 12

strep

Question 13

what imaging technique is best for looking at perenchymal abnomallies

Answer 13

MRI > CT

Question 14

what does normal CSF looks like

Answer 14

clear 
leukocytes = 0-5
neg gram stain
prot = <0.4
glucose = 2.2-2.3

Question 15

what will the CSF look like in bac meningitis

Answer 15

turbid
100-200 polymorphs
pos gram stain
pro = 0.5-3
glucose < 2.2

Question 16

what will the CSF look like in viral meningitis

Answer 16

slightly turbid/clear
15-500 polymorphs
neg gram stain
pro 0.5-1
gluc normal

Question 17

what will the CSF look like in chronic meningitis/brain abscesses

Answer 17

slightly turbid/clear
30-500 lymphocytes
neg gram stain
prot 1-6
gluc <2.2