Encephalitis Flashcards
def
inflammation of brain parenchyma
aetiology
most cases are due to viral infection
non-viral causes are rare
what are the viral causes of encephalitis
1 HSV 1+2 (most common in UK) 2 arboviruses 3 CMV (immunocompromised) 4 EBV 5 VZV
what are arboviruses transmitted by
mosquitoes
what are the non-viral causes of encephalitis
1 any bacterial meningitis 2 TB 3 malaria 4 legionella 5 aspergillosis
epi
10 per 100,000 PA in UK
history
subacute onset (hours to days) of: 1 headache 2 neck stiffness 3 photophobia (symptoms of meningism) 4 behavioural changes 5 drowsiness + confusion
associated with seizures + foreign travel + animal bite
examination
associated with decreased consciousness (plus deteriorating GCS), seizures, pyrexia
signs of meningism
signs of raised intracranial pressure
what are the signs of meningism
neck stiffness
photophobia
kernigs test positive
what is kernigs test and what does a positive result indicate
thigh flexed at the hip and knee at 90 degree angles
subsequent extension in the knee is painful (leading to resistance)
meningitis
SAH
what are the signs of raised intracranial pressure
HTN
bradycardia
investigations
1 bloods -FBC (increased lymphocytes) -glucose (compare with CSF glucose) -viral serology 2 MRI/CT -HSV produces characteristic bilateral oedema in temporal lobes 3 LP -typically increased lymphocytes and protein, with decreased glucose
what are the risk factors for encephalitis
> 65yrs
animal/insect bites
foreight travel
management
aciclovir
why is blood glucose compared with csf glucose in encephalitis
discriminates between bacterial meningitis and viral menigitis
bacterial meningitis - low CSF glucose
viral meningitis - normal CSF glucose