HSV Encephalitis Case

Question 1

Encephalitis and meningitis often appear the same, but what are some symptoms that would clue you into encephalitis?

Answer 1

seizures, stupor, coma and focal neurological findigns are much more common in encephalitis

also CT changes

Question 2

Is encephalitis more often viral or bacterial

Answer 2

viral

Question 3

If the encephalitis is bacterial, what is usually the cause?

Answer 3

Rickettsial - RMSF, lyme, anaplasmosis, powasan

Question 4

What lab test do you largely use to determine what virus is causing the encephalitis?

Answer 4

PCR

Question 5

What is targeted in viral encephalitis compared to post-infectious encephalitis?

Answer 5

viral = the neurons themselves are damaged

post-infectious = neurons spared, but you get perivascular inflammation and demyelination

Question 6

What forms of viral encephalitis are more common in the summer/fall? Winter/spring? anytime?

Answer 6

summer/fall - west nile, st louis encephalitis, eastern equine, california encephalitis

winter/spring - mumps, measles

any season - HSV1, HIV

Question 7

Besides the neurological finginds, what are some clinical presentation specific tot he following:

mumps

west nile

st. louise

rabies

VSV

Answer 7

mumps - parotitis

west nile = flaccid paralysis and tremor of eyelids

st louis = tremor of eyelids

rabies = hydrophobia, aerophobia, throat spasms, hyperactivity

VXV = vesicles

Question 8

WHat virus is the most commonc cause of fatal sporadic encephalitis in the US?

Answer 8

HSV type 1

(note HSV2 is more common worldwide andin neonates)

Question 9

What are the three potential routes of pathogenesis for encephalitis?

Answer 9

1. immediate CNS invasion via the trigeminal nerve or olfactory tract
2. CNS invasion after episodes of recurrent HSV-1 infection
3. Reactivaiton of latent HSV virus within the CNS

Question 10

Are the symptoms of encephalitis more likely to e due to cell damage from the virus or from the immune system?

Answer 10

the immune system

Question 11

What would you see in CSF with a viral encephalitis?

Answer 11

increased WBCs with lymphocytes

increased RBCs

increased protein

Low glucose would be very uncommon in this place

Question 12

What is the gold standard to diagnose an HSV1 encephalitis?

Answer 12

PCR ont he CSF looking for herpes simplex DNA

Question 13

What sort sof imaging studies should you do if you suspect a viral encephalitis?

Answer 13

head CT first, but it’s poorly sensitive and will often be normal in ealry disease

MRI is the most sensitive and specific for this - especially with temporal lobe abnormalities like our patient had

EEG

Question 14

What is the empiric treatment for viral encephalitis?

Answer 14

IV acyclovir