Meningitis Flashcards
Define meningitis
Inflammation of the leptomeningeal (pia and arachnoid mater) coverings of the brain, most commonly due to infection
List the broad causes (aetiology) of meningitis
Bacteria
Viruses
Fungal
Other ;
- Aseptic meningitis (not due to microbes)
- Mollaret’s meningitis (recurrent benign lymphocytic meningitis)
Name the risk factors for meningitis?
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
What is the role of the spleen in the immune system?
- HUGE reservoir for monocytes, which become dendritic cells & macrophages.
- Important in generation of IgM memory B cells - helps in response to repeat infections.
- 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
Why is sickle cell disease an issue in meningitis aetiology?
In sickle cell, the macrophages get ‘blocked’ when engulfing the abnormally shaped RBCs = less of them to respond to infection.
Summarise the epidemiology of meningitis
• UK: 2500 notifications/yr
Recognise the presenting symptoms of meningitis
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
Which areas of history is particularly important for menigitis diagnosis?
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
Recognise the signs of meningitis on physical examination
• 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
Identify appropriate investigations for meningitis
• 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
Generate a management plan for meningitis
• 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
Identify possible complications of meningitis
- 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)
Summarise the prognosis for patients with meningitis
- Mortality rate from bacterial meningitis: 10-40% with meningococcal sepsis
- Viral meningitis is self-limiting
opening pressures?
Normal - Viral
High - everything else
