Infection: Encephalitis

Question 1

What is encephalitis?

Answer 1

Inflammation of the brain substance, although meninges often also affected

Question 2

Encephalitis can be caused by…

Answer 2

Direct invasion of brain by neurotoxic viruses e.g HSV
Delayed brain swelling following dysregulated neuroimmunological response to an antigen (usually a virus) = post infectious encephalopathy - can follow chickenpox
A slow virus infection such as HIV or subacute sclerosing panencephalitis (SSPE) following measles

Question 3

Initially it may not be possible to differentiate meningitis for encephalitis. True or false?

Answer 3

True - treatment for both should be started

Question 4

What are the most common causes in the UK?

Answer 4

Enteroviruses
Respiratory viruses e.g influenza
Herpes viruses e.g HSV, VZV, HHV-6

Question 5

Is HSV a rare cause of childhood encephalitis?

Answer 5

Yes but can have devastating long term consequences, so all children with encephalitis should be treated with high dose IV acyclovir until diagnosis ruled out

Question 6

Do most children with HSV encephalitis have outward signs of herpes infection?

Answer 6

No

Question 7

What is used to detect HSV in the CSF?

Answer 7

PCR

Question 8

HSV encephalitis is a destructive infection, so what what may the electroencephalogram and CT/MRI show?

Answer 8

Focal changes - especially within temporal lobes

CT shows gross atrophy from loss of neuronal tissue

Question 9

How long should acyclovir be given?

Answer 9

3 weeks, as relapses May occur with shorter course