chem path + microbio

Question 1

3 layers of BBB

Answer 1

1. endothelial - protects from blood borne exogenous agents
2. csf + tight junctions - prev large and/or hydrophylic molecules
3. arach epith

Question 2

csf gluc conc relation for mening

Answer 2

n - 0.6 to 0.8 (same as plasma)
low - bacterial mening

exceptions herpes, mumps, malig dx

Question 3

scf lactate levels rel to mening

Answer 3

used to distinguish early bacterial from viral

higher is in bacterial

nb increased in hypoxic state, isch or seizure

Question 4

asdenosine deaminase (ada) in csf of mening

Answer 4

used to distinguish tb mening from other forms
inc ada suggestive of tb

Question 5

csf testing in demyelinating dx

Answer 5

measure csf and serum IgG and albumin
this used to calc IgG index
n= 0.3-0.7
>0.7 suggestive of multiple scler
&
inc myelin basic protein in csf
(prot released into scf my damaged sheat)

Question 6

csf analysis of subarach haem

Answer 6

if pt presents after 12 hours ct gives no result

after haem into csf rbcs are conv to bili which stains it yellow

the concs of the different stages of degradation of rbs can help det the time of bleed

Question 7

xanthochromia

Answer 7

yellow tint csf

Question 8

causes of xanthochromia

Answer 8

usually previous subarach haem

very high csf prot conc
jaundice (inc bili)
meningeal melanoma
rimfampicin therapy

Question 9

test for csf leak

Answer 9

b 2 transferin only present in csf

so if its not clear what fluid is leaking post trauma, check for this

Question 10

neonatal mening cause and common microbe

Answer 10

gr b streptococ - natural part of vaginal flora

during birth process/ hands of healthcsre workers/ mum