Encephalitis W4 Flashcards
what is encephalitis?
inflammation of the brain parenchyma (functional tissue in brain)
types of encephalitis?
viral
autoimmune/paraneoplastic
aetiology of viral encephalitis?
herpes simplex virus (HSV) (90% HSV1, 10% HSV2)
Varicella zoster (VZV)
HIV patients
what does varicella zoster cause other than viral encephalitis
chicken pox
shingles
co-occurring symptoms in viral encephalitis due to varicella zoster
dermatomal rash
what may be present in viral encephalitis due to varicella zoster
immunosuppression (due to eg HIV, steroids etc)
what condition should be tested for in patients with suspected viral encephalitis?
HIV
global causes of encephalitis?
Japanese encephalitis
west Nile
rabies
what is rabies?
a form of viral encephalitis
pathophysiology of viral encephalitis?
virus invades brain tissues
inflammation arises
secondary swelling, necrosis, haemorrhage
clinical features reflect inflammation and necrosis
how do different viruses invade the brain (viral encephalitis)
HSV - via olfactory nerves
VZV - via retrograde transport eg trigeminal nerve
which area of the brain does HSV classically inflame?
HSV causes inflammation in temporal lobes
clinical features of encephalitis?
headache
fever
seizures (classic symptom)
confusion
decreased consciousness
focal deficits
meningism not typical
onset and progression of encephalitis?
acute onset
rapid progression
rapidly fatal if untreated
diagnosis for encephalitis - CT features?
low sensitivity compared to MRI
may see hypoattenuating regions (darkness)
diagnosis for encephalitis - MRI features?
highly sensitive
areas of oedema +/- haemorrhage
diagnosis for encephalitis - CSF investigations?
lumbar puncture
elevated lymphocytes and protein. normal glucose
diagnosis for encephalitis - EEG?
electroencephalography
particularly useful if seizures are suspected
may show slowing or epileptiform discharges (spikes/sharp waves)
management of viral encephalitis?
antiviral therapy
if suspected then treat even before diagnostic tests
supportive therapy (seizure management, ICU support)
rehabilitation
issues in survivors of viral encephalitis?
cognitive impairment (memory, planning, reasoning, communication)
weakness, dysphasia
complications and outcomes of viral encephalitis
decreased consciousness and coma
seizures
cerebral oedema
permanent focal damage
secondary autoimmune encephalitis
what can permanent focal damage due to viral encephalitis lead to?
dysphasia, motor weakness, visual field defects, impaired swallowing, amnesia, cognitive impairment
