Neuro infection Flashcards
Define meningitis, encephalitis and myelitis
Meningitis; inflammation (/infection) of the meninges
Encephalitis; inflammation (/infection) of the brain substance
Myelitis; inflammation (/infection) of the spinal cord
What is the classical triad of clinical features associated with meningitis?
Fever
Neck stiffness
Altered mental status
Describe the clinical presentation of meningitis
Progressive headache "classical triad" Meningism Cerebral dysfunction including confusion/delirium and declining conscious level Petechial skin rash Other - cranial nerve palsy - seizures - focal neurological deficits
What type of meningitis is most closely associated with a petechial skin rash?
Meningococcal meningitis
can present in viral meningitis but this is less common
Describe what is meant by “meningism”
Pattern of symptoms including;
- neck stiffness
- photophobia
- nausea/vomiting
Why is an LP contraindicated in patients with a reduced conscious level? What should be done instead?
Reduced conscious level could be a sign on raised ICP, and doing an LP could result in tonsillar herniation (due to release of pressure at the bottom of the spinal cord).
A CT scan should be done first - if this is clear then an LP can be done
Give five contraindications to performing an LP
Focal neurological deficit New-onset seizures Papilloedema Abnormal level of consciousness that interferes with proper neurological examination Severe immunocompromised state
Describe the differential diagnosis of meningitis aetiology
Inflammation - e.g. sarcoidosis Infective - bacterial, viral, fungal Drug-induced - NSAIDs, IVIG Malignancy - metastatic cancer - haematological cancer e.g. leukaemia, lymphoma, myeloma
Which bacteria are most commonly associated with meningitis?
Meningococcus e.g. neisseria meningitidis
Pneumococcus e.g. streptococcus pneumoniae
Haemophilus influenzae
Which viruses are most commonly associated with meningitis?
Enterovirus (transmission route - through intestine)
What investigations should be done if meningitis is suspected?
Blood cultures (look for bacteraemia) Lumbar puncture (CSF culture and microscopy) Imaging (used if LP is contraindicated)
What would you expect to find in the CSF of a patient with bacterial meningitis?
Increased opening pressure
High cell count, mainly neutrophils
Low glucose
High protein
What would you expect to find in the CSF of a patient with viral meningitis?
Opening pressure is high or normal
High cell count, mainly lymphocytes
Normal glucose
Protein is slightly increased
Which virus is the commonest cause of viral encephalitis in europe? How is this diagnosed? Which drug is used to treat it?
Herpes simplex virus
Lab diagnosis by PCR of CSF
Treat with aciclovir (on clinical suspicion; don’t wait for test results)
Which arboviruses can cause encephalitis?
West-Nile virus St Louis encephalitis Western equine encephalitis Tick-borne encephalitis Japanese encephalitis
