Viral Encephalitis Flashcards
What is the break down of causes of encephalitis?
50% are idiopathic
20-50% are viral
incidence is higher in children
What is the most common viral causes of aseptic meningitis
Enteroviruses are the most common
- influenza
- mumps
- HIV
- herpes
- varicella zoster
What is the most common fungal cause of aseptic meningitis?
Cryptococcus neoformans
- \only in immunocompromised patients*
Symptoms of viral meningitis
Sudden fever
Severe headache
Nausea/vomiting
Double vision
Drowsiness
Photophobia
Stiff neck
What are lab result indicative of viral meningitis
Protein < 100mg/dL
- higher = bacterial
Normal glucose
- less = bacterial
Predominantly lymphocytes with <2000 cells/mcL
Encephalitis vs meningitis main differences
Encephalitis
- produces AMS w/ motor/sensory defects, Behavior changes and speed problems
Meningitis
- normal mental study’s and cerebral function
Treatment of acute encephalitis
Empirical treatment with acyclovir, vancomycin and a 3rd gen cephalosporin.
if you know the agent you can treat the agent specifically, but this is life threatening so dont wait
What are herpes type 1 and 2 most commonly known for
1 = cold sores
2 = genital lesions
What are the 1st and 2nd stages of herpes infections
1st = primary mucocutaneous infections
2nd = latent infection that reoccurs with stress.
- the virus moves to the neuronal ganglia
Herpes simplex encephalitis
- Most common sporadic cause of encephalitis*
- accounts for 50-75% of identified viral causes of encephalitis
- single most important cause of fatal sporadic encephalitis
Is a neurotrophic virus
Is predominately caused by the HSV-1 strain
Where in the brain is herpes simplex encephalitis localized to?
Frontal and temporal lobes
- induces hemorrhagic and lysis processes
Treatment of herpes simplex encephalitis
Early IV acyclovir
- when surviving, patients often experience epilepsy*
How does acyclovir stop herpes virus?
Acyclovir is converted via viral thymidine kinases and viral DNA polymerases into acyclovir triphosphate.
Acyclovir triphosphate is added to DNA strand and halts synthesis (since it cant add any more nucleotides to the strand)
Varicella zoster encephalitis
2nd leading cause of viral encephalitis
Common in:
- children with cerebellar ataxia or within 1 week after chickenpox rash
- adults following reactivating (2/3 of adult patients have a zoster rash)
- adults with altered mental status, focal neurologic signs and cranial neuropathies
Treatment of varicella zoster encephalitis
IV acyclovir
there is a vaccine to prevent before getting it
Rabies encephalitis
Replication of the rabies virus in the CNS via traveling up neurons attached to myocytes.
Treatment of rabies
Human rabies IgG and vaccinations
must administer before symptoms
Arboviruses
Any large group of viruses that a re transmitted by mosquitoes, ticks and other Arthropoda
Mosquitoes
- equine encephalitis
- St. Louis encephalitis
- La crosse encephalitis
- west Nile
Ticks
- powassan
LaCrosse Encephalitis
Occurs primarily in late spring and early fall
Most common in children under 16
Symptoms
- vomiting, headache, fever and lethargy
- seizures and coma are rare but possible
West Nile encephalitis
Most common cause of epidemic viral encephalitis in the US
Usually mild but can be fatal
Most common in elderly diabetic patients and the immunocompromised
If reaches brainstem, does cause coma
Lymphocytic choriomenigitis virus
Virus found in rodents and only infects humans via bite, direct contact with contaminated material or inhalation of viral particles
Clinical hall mark = biphasic illness
- fever, headache, malaise, nausea and myalgia
- gets bad at first, then better temporally and then enters a CNS phase
- once it hits CNS phase, gets really bad.
