CNS Infections Flashcards
What is meningitis?
Inflammation of meninges (dura mater/arachnoid mater & pia mater) surrounding brain & spinal cord
Result in irritation of nerves that pass through meninges
What are the causes of meningitis?
Viral, bacterial and fungal
What is the early signs of meningitis?
Meninges are highly inflamed and red in colour
What is the late/chronic sign of meningitis?
White colour = fibrosis
*extensive meningitis = whole brainstem affected
What are the symptoms of meningitis?
- Fever
- Headache
- Irritability
- Delirium
- LOC
- Stiff neck (May feel pain when flexing neck + chin cannot touch sternum; *most common sign)
- Vomiting
- Joint pain
- Purpura (in some cases)
*meningococcal meningitis can cause ecchymoptic patches over skin
What are the 2 signs that confirms the diagnosis of meningitis?
- Kernig sign (hamstring muscle spam when trying to extend flexed knee when hip is flexed)
- Brudzinski sign (severe neck stiffness which causes hips and knees to flex when neck is flexed)
What are the causal bacteria for bacterial meningitis?
- Streptococcal pneumonias
- Haemophillus influenzae
- Meningococcus
What does bacterial meningitis show?
- Purulent exudate and thormbosed veins on surface and base of brain
- Haemorrhagic infarction of penetrating vessels
- Neutrophils in subarachnoid space and CSF
What can bacterial meningitis cause?
Septicaemia and haemorrhage over body = high mortality
What is bacterial meningitis associated with?
Adrenal haemorrhagic necrosis (Waterhouse-friderischen syndrome)
How is TB spread for TB meningitis
Haematogenous spread to CNS (primary site: lungs)
What can you see in TB meningitis?
Small yellow nodules (tubers) on brain surface
Histology shows langerhans giant cells, lymphocytes and vasculitis
What viruses are involved in viral meningitis?
- Mumps
- Measles
- Echovirus
What investigations are done for meningitis?
- CT scan (to exclude mass lesion in drowsy/unconscious pt)
- Lumbar puncture
- CSF contains
a) neutrophils (>5000 cells/mm3): bacterial meningitis
b) lymphocytes (viral and tb meningitis)
c) increased protein
d) decreased glucose (esp bacterial meningitis)
e) gram stain may show organisms (gram +ve/-ve)
- CSF contains
- Blood culture (TRO septicaemia)
What are the treatments available for meningitis?
- IV abx
- Supportive measures
- Rifampicin prophylactics for contacts of meningococcal meningitis
- Vaccination
- quadrivalent vaccine A, C, Y, W135
- HIB vaccine against H. Influenza B meningitis