encephalitis Flashcards
inflammation of brain parenchyma
encephalitis
what causes encephalitis?
viruses is by far the main cause of encephalitis
ocassionally bacteria is the culprit
what is the difference between encephalitis and meningitis?
both are associated with lethargy and headache but meningitis has no alteration of mental status
also more common with encephalitis is seizures, flaccid paralysis and paresthesia
major routes of entry to CNS (3)
- olfactory nerve pathway
- peripheral nerve pathway
- hematogenous spread
most pathogens enter hematogenous through (2) ways
- enter CSF via choroid plexus
2. direct infection of endothelial cell of brain vessels
Herpes simplex enters the CSF is through
direct peripheral neuronal spread
Two ways pathogens do damage in CSF
- Direct damage by viral invasion of neurons
- Post-infectious/ADEM- host inflammatory response that then results in damage due to influx of inflammatory cells, swelling, etc.
hallmark of encephalitis
altered mental status
Most causes of encephalitis cannot be distinguished by CSF profile!!
so true
the only one encephalitis virus that can be treated
Herpes viruses
Which herpes virus is more common to cause enccephalitis?
HSV-1
entry of HSV-1 to CNS? what type of encephalitis do we get?
from peripheral nerves causing a acute focal encephalitis with temporal lobe predilection
most sensitive way to pick-up differences in temporal lobe
EEG
diagnosis of HSV encephalitis
CSF PCR is highly sensitive and specific
***brain biopsy used to be the gold standard but it is not done anymore
first line treatment of HSV encephalitis
acyclovir
eastern equine encephalitis (EEE) end stage
humans and horses
entry of EEE
hematogenous route
Most severe arthropod-borne illness in North America
EEE
diagnosis of EEE
IgM ab to the virus in CSF and neutralizing ab
RNA flavivirus
Most common vector borne cause of encephalitis in US today. Cases began in U.S. in 1999
west nile virus
west nile virus is different due to one symptom we dont tend to see with other encephalitis
polio-like syndrome—> flaccid paralysis
west nile virus has a direct patient to patient transmission
nope, no direct. rarely can be transmitted by non-vectored means
west nile virus diagnoisis
serology (IgM)
2 forms of rabies but both lead to death
- encephalitic rabies
2. paralytic rabies
type of rabies:
- ascending paralysis
- later cerebral involvement
Paralytic Rabies
type of rabies:
Agitation
Hypersalivation
Hydrophobia
Bizarre behavior, disorientation, stupor, coma, death
encephalitic rabies
CNS pathology in rabies
negri bodies – eosinophilic cytoplasmic inclusions in neurons represent accumulated viral particles
rabies prevention
- neutralize virus with human rabies immune globulin
2. rabies virus specific immune response induction (vaccine)
