encephalitis

Question 1

define encephalitis?

Answer 1

inflammation of the brain parenchyma

Question 2

cause of encephalitis?

Answer 2

• Most commonly due to VIRAL INFECTION

* Commonly affects the temporal and inferior frontal lobes.

Question 3

most common viral cause of encephalitis?

Answer 3

o Herpes Simplex Virus - MOST COMMON in the UK (95%)

Question 4

presenting complaint of encephalitis?

Answer 4

• Subacute onset (hours to days)
• Headache
• Fever
• Vomiting
• Neck stiffness
• Photophobia
• Behavioural changes
• History of seizures
• Obtain a detailed TRAVEL HISTORY

Question 5

how to differentiate encephalitis from meningitis?

Answer 5

altered mental state.

Question 6

what might seizures of the temporal lobe present as?

Answer 6

motionless staring, confusion, disorientation, aura (feeling of unfamiliarity)

Question 7

other signs of encephalitis?

Answer 7

•	Signs of Meningism: 
o	Neck stiffness  
o	Photophobia 
o	Kernig's test positive  
•	Signs of raised ICP: 
o	Cushing's Response: 
hypertension + bradycardia + irregular breathing  
o	Papilloedema  
•	Focal neurological signs  
•	MMSE may reveal cognitive/psychiatric disturbance

Question 8

what might a lumbar puncture show?

Answer 8

lymphocytosis, elevated protein

Question 9

what investigations should be carried out?

Answer 9

o CT: medial temporal and inferior frontal changes
o MRI is better
o EEG pattern: lateralised periodic discharges at 2Hz
o PCR for HSV
o Glucose is usually normal