encephalitis Flashcards
definition of encephalitis
inflammation of the brain parenchyma
aetiology of encephalitis
viral - mainly
non-viral
immunocompromised
- CMV
- toxoplasmosis
- listeria
autoimmune or paraneoplastic
- Ab - eg anti-NMDA or anti-VGKC
viral causes of encephalitis
HSV1 and 2 - most common in UK
herpes zoster
mumps
adenovirus
coxsackie
echovirus
enterviruses
measles
EBV
HIV
rabies - Asia
Nipah (malaysia)
arbovirus transmitted by mosquitoes eg japanese B encephalitis (Asia), St. Louis and West Nile encephalitis (USA).
VZV
tick-borne encephalitis
non-viral causes of encephalitis
syphillis
staphyloccocal aureus
bacterial meningitis
TB
malaria
lyme disease
legionella
leptospirosis
aspergillosis
cryptococcus
schistosomiasis
typhus
epidemiology of encephalitis
Annual UK incidence is 7.4 in 100 000.
sx of encephalitis
many cases - mild and self limiting
subacute onset hrs-days
- headache
- fever
- vomiting
- neck stiffness
- photophobia ie symptoms of meningism with behavioural changes
- drowsiness, reduced GCS
- confusion
history of seizures
focal neurological symptoms - dysphagia, hemiplegia
travel history or animal bite
signs of encephalitis
reduced consciousness with deteriorating GCS
seizures
pyrexia
signs of meningism
- neck stiffness
- photophobia
- Kernig’s test positive
signs of raised ICP
- htn
- bradycardia
- papilloedema
focal neuro signs
mini mental exam - cognitive/psychiatric disturbances
Ix for encephalitis
blood
throat swab
MSU
MRI/contrast enhanced CT
LP
EEG - May show epileptiform activity, e.g. spiking activity in temporal lobes.
brain biopsy - rare
blood for encephalitis
FBC - high lymphocytes
UE - SIADH may occur
glucose - compare with CSF glucose
viral serology
ABG
blood cultures
serum for viral PCR
toxoplasma IgM titre
malaria film
MRI/contrast CT for encephalitis
excludes mass lesion
HSV produces characteristic bilateral oedema of the temporal lobe on MRI
Meningeal enhancement suggests meningoencephalitis.
do before LP
LP for encephalitis
high lymphocytes, monocytes, protein
glucose normal/low
CSF culture difficult - viral PCR normally 1st line including HSV
