Meningitis

Question 1

Define meningitis

Answer 1

Inflammation of the leptomeningeal (pia and arachnoid mater) coverings of the brain, most commonly due to infection

Question 2

List the broad causes (aetiology) of meningitis

Answer 2

Bacteria
Viruses
Fungal

Other ;

1. Aseptic meningitis (not due to microbes)
2. Mollaret’s meningitis (recurrent benign lymphocytic meningitis)

Question 3

Name the risk factors for meningitis?

Answer 3

RISK FACTORS;

Close communities (e.g. college halls)
Basal skull fractures
Mastoiditis

Sinusitis
Inner ear infections
Alcoholism

Immunodeficiency
Splenectomy - 2ndary to sepsis - immunodeficient
Sickle cell anaemia

CSF shunts
Intracranial surgery

Question 4

What is the role of the spleen in the immune system?

Answer 4

1. HUGE reservoir for monocytes, which become dendritic cells & macrophages.
2. Important in generation of IgM memory B cells - helps in response to repeat infections.
3. Massive role in combat against Pneumonia and meningits (S,pneumoniae + N. meningitidis) - due to the memory B cells.

So without a spleen - huge risk of sepsis meningitis and pneumonia

Question 5

Why is sickle cell disease an issue in meningitis aetiology?

Answer 5

In sickle cell, the macrophages get ‘blocked’ when engulfing the abnormally shaped RBCs = less of them to respond to infection.

Question 6

Summarise the epidemiology of meningitis

Answer 6

• UK: 2500 notifications/yr

Question 7

Recognise the presenting symptoms of meningitis

Answer 7

Cardinal;
• Severe headache
- if bacterial meningtis then sudden onset, within minutes - life threatening
- if viral meningitis, is progressive
• High Fever!
• Vomiting

• Photophobia
• Neck or backache
• Irritability
• Drowsiness
• High-pitched crying or fits (common in children)
• Reduced consciousness

Question 8

Which areas of history is particularly important for menigitis diagnosis?

Answer 8

IMPORTANT: take a good travel history and exposure history and take not of exposure to any of the following;

○ Rodents (lymphocytic choriomeningitis virus)
○ Ticks (Lyme borrelia, Rocky Mountain spotted fever)
○ Mosquitoes (West Nile virus)

○ Sexual activity (HSV-2, HIV, syphilis)
○ Travel

Question 9

Recognise the signs of meningitis on physical examination

Answer 9

• Signs of MENINGISM
○ Photophobia
○ Neck stiffness
○ Kernig’s Sign - with the hips flexed, there is pain/resistance on passive knee extension
○ Brudzinski’s Sign - flexion of the hips when the neck is flexed

Signs of INFECTION
○ Fever
○ Tachycardia
○ Hypotension
○ Non- blanching purpuric RASH
○ Altered mental state - CONFUSION

Question 10

Identify appropriate investigations for meningitis

Answer 10

• Bloods
○ Two sets of blood cultures - for septicaemia

• Imaging
○ CT scan - if raised ICP suspected before Lumbar Puncture. Excludes mass lesion

• Lumbar Puncture
○ MC& S - microscopy, culture & sensitivity

○ Bacterial meningitis:
• Cloudy CSF
• High neutrophils!!!
• High protein
• Low glucose

○ Viral meningitis:
• High lymphocytes
• High protein
• Normal glucose

○ TB meningitis:
• Fibrinous CSF
• High lymphocytes
• High protein
• Low glucose

Question 11

Generate a management plan for meningitis

Answer 11

• IMMEDIATE IV Antibiotics (before LP)
○ First choice: 3rd generation cephalosporin (e.g. cefotaxime or ceftriaxone) -> 3 C’s

○ Benzylpenicillin may be used as an initial blind therapy (i.e. in the community)

• Dexamethasone IV - antiinflammatory actions
○ Given shortly before or with the first dose of antibiotics
○ Associated with a reduced risk of complications

• Resuscitation
○ Manage in ITU
○ Notify public health services

Question 12

Identify possible complications of meningitis

Answer 12

• Septicaemia
• Shock
• DIC
• Renal failure
• Seizures
• Peripheral gangrene
• Cerebral oedema
• Cranial nerve lesions
• Cerebral venous thrombosis
• Hydrocephalus
• Waterhouse-Friderichsen Syndrome (bilateral adrenal haemorrhage caused by severe meningococcal infection)

Question 13

Summarise the prognosis for patients with meningitis

Answer 13

• Mortality rate from bacterial meningitis: 10-40% with meningococcal sepsis
• Viral meningitis is self-limiting

Question 14

opening pressures?

Answer 14

Normal - Viral

High - everything else