Neuro

Question 1

What 3 bugs are most commonly implicated in community acquired bacterial meningitis?

Answer 1

1. Step pneumoniae
2. Neisseria meningitidis
3. Haemophilus influenzae

Question 2

What is the pathogenesis of acute bacterial meningitis?

Answer 2

1. Nasopharyngeal colonisation occurs.
2. Blood stream invasion occurs across the mucosa
   3 Circulation of bacteria to the CNS via bloodstream
   - In immunocompetent the bacteria is usually cleared by mucosal immunity. Co-infeciton with a resp virus increases inflammation.
   -Occasionally it spreads directly through the olfactory bulb and therefore no bacteraemia is present (10-30%\0

Question 3

When should dexamethasone be given in meningitis and why?

Answer 3

In suspected pneumococcal ABM with first antibiotics
- Decreases morbidity a.w CNS tissue damage e.g. deafness, CVA, epilepsy, LD

Question 4

How does meningitis present?

Answer 4

Early - headache, leg pain, cold hands and feet, abnormal skin colour
Later - neck stiffness, photophobia, kernig +ve, reduced GCS, seizures, opishotonus, petechial rash, sepsis

Question 5

What are the CI to LP in suspected ABM?

Answer 5

If suspected mass lesion, focal signs, papilloedema, trauma, middle ear pathology, coagulopathy

Question 6

What is a normal CSF opening pressure?

Answer 6

7-18cm

Question 7

What might the LP show in ABM?

Answer 7

• Raised opening pressure
• Turbid appearance
• Predominant cell type = polymorph
• Glucose = < 1/2 plasma
• Protein (g/L) > 1.5
• Cell count 90-1000+/mm3
• Bacteria on smear and culture
• Lactate > 3.5 predicts bacterial meningitis quite well

Question 8

What are the LP findings in TB meningitis?

Answer 8

• Appearance = fibrin web
• Predominant cell type = mononuclear
• Cell count = 10-1000
• Glucose = < 1/2 plasma
• Protein = 1-5
• Bacteria - often none seen

Question 9

What are the LP findings in someone with viral meningitis

Answer 9

• Appearance = clear
• Predominant cell type = mononuclear
• Cell count = 50-1000
• Glucose = > 1/2 plasma
• Protein = < 1
• Bacteria = none seen of culutres

Question 10

What are the normal CSF values?

Answer 10

1. < 5 lymphocytes may be normal as long as there are no neutrophils
2. Protein 0.15-0.45 g/L
3. Gluc 2.8-4.2

Question 11

What causes reduced CSF glucose?

Answer 11

Sepsis
Parasitic meningitis e.g. from eating snails
Herpes encephalitis
Low blood glucose
Sarcoid
CNS vasculitis