CNS Infections Flashcards
Differential diagnosis of CNS infection?
Meningitis Encephalitis Subarachnoid Haemorrhage Brain Abscess Space occupying lesion
Viral meningitis:
Most common cause?
Also, list the 3 ways bacteria can spread into the CNS.
Most common cause is ECHO virus.
From the nasopharynx, direct extension due to skull fractures or spread from remote foci due to sepsis.
Herpes simplex encephalitis managament?
Recognition has to be rapid e.g. <6hours.
Give high dose IV aciclovir.
If delay in investigations (LP, EEG, MRI) start pre-emptive treatment as prompt therapy improves outcomes.
Triad of meningism?
1) Photophobia
2) headache
3) Neck stiffness.
Most common cause of bacterial meningitis in under 4years?
H. Influenzae
Most common cause in 10-21 years old?
Meningococcal.
21 and onwards most common cause?
Pneumococcal > meningococcal
Pneumococcal - Strep pneumonia
What is the most common cause of bacterial meningitis in the immunocompromised?
Listeria monocytogenes.
What is the bacteria in meningococcal meningitis?
Neiseria meningitidis.
Military recruits are vaccinated with a purified capsular polysaccharide to prevent epidemics in training camps.
What is the antibiotic of choice in listeria monocytogenes meningitis?
IV ampicillin/amoxicillin.
Ceftriaxone no value as intrinsically resistant.
3 main signs in bacterial meningitis?
Fever
Stiff neck
Alteration in consciousness
Lumbar puncture principles?
- Only if clinical feasible.
- Be cautious if increased ICP possible.
- Utilise sitting position if necessary.
- Measure opening pressure if flow fast.
- Be careful in setting of delirium.
- Treat with antibiotics FIRST.
- CSF pleocytosis is NOT bacterial meningitis.
Typical CSF findings in viral meningitis?
Lymphocytes
Normal or slightly high protein
Usually normal glucose.
CSF findings in bacterial meningitis?
Predominantly polymorphs / neutrophils
High Protein
Less than 70% blood glucose.
TB meningitis CSF findings?
Lymphocytes
High or very high protein
Less than 60% blood glucose.
