Flashcards in NS Infection - Meningitis/Encephalitis Deck (16):
Causes of Meningitis?
- Inflammatory e.g. Sarcoid
- Drugs Induced e.g. NSAIDs
- Malignant (Metastatic or Leukemia)
How do we approach meningitis?
- Blood Cultures & Gram Stain
- LP (CSF culture & Microscopy)
- Only image if LP is contraindicated
How do we approach encephalitits?
- Blood Culture
- LP (PCR of the CSF for viral DNA)
When would an LP be contraindicated?
You don't do it if there's sign of a mass or swelling as the pressure could cause herniation when you repressurise by puncturing it.
- Focal Neuro deficits
- New Seizures
- Severe Immunocompromisation
What would you find on an LP in meningititis?
- raised pressure
- Raised cell count (Mainly Neutrophils)
- Low Glucose (Bacteria consume it)
- Very High Protein
- Normal/raised pressure
- Raised Cell Count (Mainly Lymphocytes)
- Normal glucose (~60% of blood glucose)
- Slightly raised protein
Causes of Encephalitis?
- Infective (HSV is main cause of encephalitis, Enterovirus etc)
- Inflammatory (i.e. autoimmune)
- Metabolic (Hepatic, uraemic, hyperglycaemic)
- Malignant, either a metastases or a paraneoplastic syndrome
- Post Ictal (After Seizure)
What microorganisms cause infective meningitis?
Neisseria Meningitidis (Meningococcus)
Streptococcus Pneumoniae (Pneumococcus)
How do we treat viral encephalitis?
Aciclovir based on clinical suspicion of Viral encephalitis.
How does HSV cause encephalitis?
It goes latent, in your trigeminal or sacral ganglion
It reactivates later and encephalitis is a rare complication, which mostly results from Type 1 HSV
Name some enteroviruses and how you spread/test for them in encephalitis?
Polioviruses, coxsackie virus, echovirus
Do PCR of a stool sample if you suspect
Other than HSV and Enteroviruses what else causes infectious encephalitis?
Common in other parts of the world they are vector-transmitted (tick or mosquito) so a travel history is important
E.g. West Nile Virus (Location name viruses dont relate to current geographical distribution)
How does Meningitis Present?
Classic Triad of Fever, neck stiffness and altered mental status
- Short history of headache
- Meningism (Stiff neck, photophobia, N&V)
Cerebral dysfunction e.g. confusion is common and many have a lowered GCS
Cranial Nerve Palsies, Seizures and focal neuro deficits can occur
What presentation of meningitis is specific to which cause?
Petechial Skin Rash
A hallmark of meningococcal meningitis (But can occur in viral)
How does Encephalitis Present?
Flu-like Prodrome for 4-10 days
- Progressive Headache with Fever
- Progressive cerebal dysfunction (Seen as confusion, memory issues, behaviour etc)
- Focal Signs
How is viral encephalitis different from bacterial meningitis?
It has a slower onset and more prominent cerebral dysfunction...generally