Flashcards in Meningitis Deck (16)
What morbidity does meningitis cause?
What is meningitis?
Inflammation of the lepto - meningeal membranes
What are the 4 types of meningitis?
Para - meningeal foci
Neoplastic or paraneoplastic
What 4 infectious agents cause meningitis?
Virus - enterovirus, mumps
Bacteria - meningococcus, H. influenzae
Fungus - cryptococcus
Parasite - naegleria
What prevents infection reaching the brain?
How to organisms reach the CNS?
Bacteraemia/ Parasitaemia / viraemia - BBB most vulnerable in the capillaries of choroid plexus (leaky so pathogens get through)
Direct spread - chronic infections in cranial bones, ears, sinus, oral cavity, Upper Resp tract
Indirect spread - infection of peripheral neurones, axonal transport, cell - cell spread of infection to connecting neurones in CNS
How does meningitis develop?
BBB more permeable, blocked blood vessels,
Oedema, CSF flow disturbances
Intercranial pressure increase, cerebral flow decreases
Cerebrovascular autoregulation lost
What factors influence the cause of meningitis?
Age - extremes - week BBB in 75 yrs
Geography - overcrowding, high temp, tropical
Immunity - chemo, steroids, transplant
Trauma - base of skull fracture
How will someone with meningitis present?
Stiff neck, fever, altered mental stability, headache
Clinically, if they show these signs then 95% meningitis but only 5% meningitis will show these signs (95% specific, 5% sensitive)
How do you collect CSF?
lumbar puncture to test CNS
How does normal CSF present?
sterile, low protein, 60%blood glucose, lymphocytes
How does CSF present in bacterial infection?
+ve gram stain, high protein, low glucose, lots neutrophils
How do you exclude other pathologies?
MRI / CT scan
What are the 5 complications with bacterial meningitis?
3) SCARRING - epilepsy
4) HYDROCEPHALUS - CSF in ventricles builds up. Ventricles swell and brain is compressed
5) TRANSENTONIAL HEMIATION - increase intercranial pressure. Brain expands inwards, compressing brain stem, compressing vasomotor and resp centres, coma/death
What is the management for meningitis?
-Antimicrobial therapy -
-Antibiotics - penicillin, chloramphenicol, vancomycin
-Steroids - good before antibiotics because their efficiency at decreasing inflammation is better
-Prophylaxis - antibiotics (prevent spread) and vaccines