Encephalitis (N) Flashcards
Define encephalitis.
Inflammation of the brain parenchyma associated with neurological dysfunction, such as altered state of consciousness, seizures, personality changes, cranial nerve palsies, speech problems, and motor and sensory deficits
What are the causes of encephalitis? (4)
- most commonly viral infection (HSV-1 most common)
- non-viral infections: bacterial, fungal, parasitic (syphilis, S. aureus)
- also in immunocompromised patients (CMV, toxoplasmosis, Listeria)
- also in those with autoimmune/paraneoplastic syndromes (associated with certain antibodies: anti-NMDA, anti-VGKC)
What is the most common cause of viral encephalitis?
HSV-1
What are some other causes of viral encephalitis? (8)
- HSV-1
- VZV
- mumps
- adenovirus
- Coxsackie
- EBV
- HIV
- Japanese encephalitis
What demographics is encephalitis most common in?
Bimodal distribution:
- age <1y
- age >65y
Describe the onset and severity of encephalitis.
- subacute onset (hours to days)
- self-limiting and mild (in most cases)
What are the clinical features of encephalitis? (8)
- initial flu-like symptoms with pyrexia and headache that persist
- altered mental state
- fever + malaise
- rash
- headache
- focal neurological deficits - depending on which area of brain is inflamed
- seizures
- meningismus - headache, photophobia, neck stiffness
What are some focal neurological deficits you might see in encephalitis? (4)
- changes in personality or behaviour
- difficulty speaking, dysphagia
- weakness or loss of movement / hemiplegia
- loss of consciousness
What are some signs of meningism you might find in encephalitis? (3)
- headache
- photophobia
- neck stiffness
What might you see on examination in encephalitis? (9)
- altered mental state + reduced consciousness
- bizarre encephalopathic behaviour
- deteriorating GCS
- acute flaccid paralysis
- seizures
- pyrexia
- meningism - headache, photophobia, neck stiffness, Kernig’s test +ve
- signs of raised ICP (Cushing’s triad, papilloedema)
- focal neurological signs
What might MMSE reveal in encephalitis?
Cognitive/psychiatric disturbance
What issue may arise secondary to encephalitis, and what are the features of this?
Raised ICP:
- Cushing’s triad:
- widened pulse pressure (hypertension)
- bradycardia
- irregular breathing
- papilloedema
What key clinical features distinguish encephalitis from meningitis? (2)
- altered mental state (and personality change)
- seizures
What do we need to remember to ask about in encephalitis?
Travel history
What are some risk factors for encephalitis? (9)
- age <1 or >65
- immunosuppression
- post-infection / viral infection
- bodily fluid exposure
- organ transplantation
- animal/insect bites
- travel
- season
- nasal/sinus irrigation
