Encephalitis and meningitis often appear the same, but what are some symptoms that would clue you into encephalitis?
seizures, stupor, coma and focal neurological findigns are much more common in encephalitis
also CT changes
Is encephalitis more often viral or bacterial
If the encephalitis is bacterial, what is usually the cause?
Rickettsial - RMSF, lyme, anaplasmosis, powasan
What lab test do you largely use to determine what virus is causing the encephalitis?
What is targeted in viral encephalitis compared to post-infectious encephalitis?
viral = the neurons themselves are damaged
post-infectious = neurons spared, but you get perivascular inflammation and demyelination
What forms of viral encephalitis are more common in the summer/fall? Winter/spring? anytime?
summer/fall - west nile, st louis encephalitis, eastern equine, california encephalitis
winter/spring - mumps, measles
any season - HSV1, HIV
Besides the neurological finginds, what are some clinical presentation specific tot he following:
mumps - parotitis
west nile = flaccid paralysis and tremor of eyelids
st louis = tremor of eyelids
rabies = hydrophobia, aerophobia, throat spasms, hyperactivity
VXV = vesicles
WHat virus is the most commonc cause of fatal sporadic encephalitis in the US?
HSV type 1
(note HSV2 is more common worldwide andin neonates)
What are the three potential routes of pathogenesis for encephalitis?
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
Are the symptoms of encephalitis more likely to e due to cell damage from the virus or from the immune system?
the immune system
What would you see in CSF with a viral encephalitis?
increased WBCs with lymphocytes
Low glucose would be very uncommon in this place
What is the gold standard to diagnose an HSV1 encephalitis?
PCR ont he CSF looking for herpes simplex DNA
What sort sof imaging studies should you do if you suspect a viral encephalitis?
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
What is the empiric treatment for viral encephalitis?