CNS Infections Flashcards
In what ways can the CNS become infected?
Direct invasion by neurotropic micro-organisms
Iatrogenic
Latent viral infection
Toxin mediated disease
Immune mediated disease
What does neurotropic mean?
Micro-organism has a tendency to attack the CNS
Give an example of a CNS infection caused by direct invasion by neurotropic micro-organisms?
Encephalitis
Meningitis
Meningoencephalitis
Give some examples of iatrogenic causes of CNS infection?
Neurosurgery
Shunts: to drain excess fluid on the brain in hydrocephalus
Give an example of a latent viral infection that causes CNS infection?
Shingles: Herpes Zoster
Give some examples of toxin mediated CNS infections?
What does ‘toxin mediated’ mean?
Botulism
Tetanus
The pathogen releases a toxin that causes the damage to the body
Give an example of some immune mediated diseases that are linked with CNS infections?
Guillain Barre
Post-infection inflammation
ADEM + AHLE
(diseases to do with demyelination)
What is Guillain Barre syndrome briefly?
When the body’s immune system attacks the peripheral nervous system
It occurs shortly after an infection, this triggers the immune system to go into overdrive
What is meningitis?
Inflammation of the meninges
Often caused by infection, but not always
What are the clinical features of meningitis?
Fever
Severe headache
Meningismus:
- photophobia
- neck stiffness
Altered mental state, not always
What is meningismus?
Symptoms that meningitis causes:
- photophobia
- neck stiffness
Only meningitis causes meningismus.
True or false?
False!
Can be caused by encephalitis and para-meningeal infections too
What is a para-meningeal infection?
Just another type of infection, such as tonsillitis
They can cause meningismus
What can cause meningitis?
Infection:
- bacteria
- virus
- fungal
- tuberculous
Non-infectious:
- tumours + cysts
- drugs
- autoimmune: SLE
- post-neurosurgery
When you see a patient with meningitis-like symptoms what should you do?
Always err on the side of caution and check for bacterial meningitis
It is very severe and if missed can be fatal
Which are common bacteria that cause meningitis in adults and children?
Neisseria meningitidis
Strep. pneumoniae
Listeria monocytogenes
Which are common bacteria that cause meningitis in neonates?
E. coli
Group B strep
Which pathogen is screened for in pregnant women? Why?
Group B streptococci
It can be picked up by neonates in the birth canal and can cause meningitis
Which viruses cause meningitis?
Mumps
Enteroviruses (like polio)
Investigations of meningitis?
Lumbar puncture promptly!
Analyse:
- cell count
- protein level
- glucose level
Blood cultures
CT: check for raised inter-cranial pressure
What is meningococcal septicaemia?
Septicaemia: infection in the bloodstream
Caused by a meningococcal pathogen