Meningitis

Question 1

What organisms commonly cause meningitis?

Answer 1

• Bacterial meningitis;
  
  • Neisseria meningitidis (aka meningococcal, gram +ve diplococcus)
  • Streptococcus pneumoniae (aka pneumococal)
• Tuberculosis meningitis
• Viral
• Fungal;
  
  • Cryptococcus neoformans

Question 2

Outline the pathophysiology of bacterial meningitis

Answer 2

Bacteria enter meningeal space due to hole in dura or via blood stream

Strep. pneumoniae & Neiseria meningitidis enter via nasopharynx

Question 3

What is the clinical presentation of bacterial, TB, fungal & viral meningitis?

Answer 3

• Acute - bacterial & viral
• Subacute - TB & fungal

Early;

• Headache
• Fever [not TB]
• Vomiting
• Low consciousness [not Viral]
• Leg pains & cold hands & feet
• Abnormal skin colour

Late;

• Meningism;
  
  • Neck stiffness
  • Photophobia
  • Kernig’s sign (pain + resistance on passive knee extension with hip fully flexed)
• Petechial rash (non-blanching)
• Seizures +/- focal CNS signs +/- opisthotonus

Signs of galloping sepsis; slow cap refil, DIC, low BP, high temp, fast pulse

Question 4

Outline the investigation & management pathway for meningitis

Answer 4

1. Classic meningococcal rash/ severe sepsis?
   
   • Yes - sepsis 6 pathway + ceftriaxone
   • No - next
2. Is the patient having seizures/ focal neurological signs/ GCS <15?
   
   • Yes - DXM + ceftriaxone + amoxicillin (>50yrs)/ aciclovir (encephalitis)
   • No - next
3. Lumbar puncture for microbiology, virology, biochemistry & cytology
   
   • DXM + ceftriaxone
   • CSF results;
     
     • Acellular - another diagnosis
     • Neutrophil -continue ceftriaxone + DXM (+amoxicillin if >50)
     • Lymphocytes - other diagnosis (viral/ TB meningitis)

• TB meningitis
  
  • CXR - pulmonary or miliary TB?
  • Tuberculin skin test
  • CT/ MR scan of brain - visualise tuberculomas & rule out abscess/ tumour
  • CSF examination - high lymphocytes & high protein
  • Treatment same as any TB
• Viral meningitis
  
  • High neutrophils early on, then high lymphocytes
  • PCR useful
• Fungal - CSS contains yeast with india ink stain