Acute and subacute encephalitis Flashcards
What are symptoms of encephalitis?
Altered level of consciousness, focal neurologic deficits (hemiparesis, aphasia, hemispatial neglect, movement disorders), Seizures can occur, coma
Can meningitis and encephalitis coexist?
Yes, called “meningoencephalitis”
What are a significant proportion of encephalitis cases likely caused by?
autoimmune disorders and postinfectious encephalitis caused by aberrant immune response to primary infection
What is the proposed case definition for encephalitis?
encephalopathy for 24 hours, plus 2 of the following: Hisroy of fever, seizures/focal neurological deficits, CSF pleocytosis, electroencephalogram characteristics consistent with encephalitis, neuroimaging abnormalities
Is viral encephalitis higher in adults or children?
Children
What is most common cause of encephalitis?
Idiopathic
What are the most common causes of encephalitis (not idiopathic) in order?
HSV-1 and HSV-2 (11-22%), VZV (4-14%), Postinfections (measles, mumps, rubella, flu) (2-11%), TB (5-8%), Autoimmune (4-8%), Enterovirus (1-4%)
How do you diagnose HSV-1 or 2 encephalitis?
PCR of the CSF
What are minor causes of encephalitis?
Arboviruses, other herpesviruses (EBV, HHV-6, HCMV), JC virus, Respiratory viruses, Rabies, mumps and measles (direct, primary infection), Bacteria
What is the differential for encephalitis?
Alphaherpesviruses, Postinfection immune responses (acute disseminated encephalomyelitis), Tuberculosis, Autoimmune, Enteroviruses, rare causes
If a patient presents with altered state of consciousness and unexplained seizure, fever or new focal neurological deficits, what should you be concerned about?
Encephalitis
What are the 3 things to do when diagnosing encephalitis?
CT scan, lumbar puncture, EMPIRIC THERAPY PRIOR TO CSF RESULTS: ACYCOLOVIR
What happens to glucose and protein levels in bacterial encephalitis?
Protein goes up, glucose down
What happens to glucose and protein levels in viral encephalitis?
Protein goes up, glucose stays the same
What should happen to a CSF sample in someone suspected to have viral encephalitis?
PCR for HSV, HSV-2, VZV and enteroviruses. Will cover 90% of everything
What lobe under an MRI would be affected in an HSV infection causing encephalitis?
Temporal lobe, it’s where the trigeminal nerve ends
What area of the brain do flaviviruses typically infect for encephalitis?
Basal ganglia and thalamus
What happens to the level of lymphocytes and neutrophils upon viral encephalitis?
Neutrophils are increased initially, decrease later and lymphocytes increase dramatically
What are the WBC counts of autoimmune causes of encephalitis?
Very low
What WBC is increased in West Nile Virus encephalitis?
neutrophils
What WBC is increased in ADEM (acute disseminated encephalomyelitis) encephalitis?
neutrophils in CSF (sometimes)
What causes of encephalitis will most likely have an abnormal MRI?
HSV (temporal lobe), ADEM (supra tentorial)
What is the tree of HSV-1 and -2?
DNA vrus, icosahedral nucleocapsid, enveloped, dsDNA linear genome (class 1)
What is the major target of antiviral therapy against herpesviruses?
proteins that are required to promote DNA replication
Are babies more likely to get encephalitis caused by HSV-1 or HSV-2?
HSV-2
What is the most common cause of encephalitis among immunocompromised patients?
VZV
How does acyclovir affect viruses?
guanine nucleoside analogue that has a high affinity for viral DNA pol and inhibits viral DNA replication. Has lower affinity for human DNA pol
Can treating patients with acyclovir/antiviral agents clear the body of the virus?
No, only works to decrease the spread of the disease, will not clear a latent infection
What is most common causes of postinfectious encephalitis?
measles, mumps, rubella, VZV, influenza
What is the most common form of postinfectious encephalitis?
Acute disseminated encephalomyelitis (ADEM)
Describe ADEM. When does it occur?
inflammatory demyelinating condition that occurs anywhere from days to 4 weeks post-viral infection (caused by type 2 hypersensitivity reaction)
What usually causes ADEM? (what kind of hypersensitivity)
type 2 hypersensitivity
What is the tree of measles virus?
Virus, ssRNA (-) group V, nonsegmented, helical nucleocapsid, enveloped, paramyxoviridae, morbillovirus
What form of encephalitis can measles complicate to?
subacute sclerosing panencephalitis (SSPE), acute postinfectious encephalomyelitis, primary measles encephalytis
What is the treatment of primary measles encephalitis?
Supportive
How does primary measles encephalitis establish itself?
invades and replicates within brain cells, injuring neurons and triggering lymphocytic infiltration.
What is the treatment of measles-induced acute disseminated encephalomyelitis?
Corticosteroids to dampen the immune response
How does measles-induced acute disseminated encephalomyelitis occur? What are some basic markers in CSF?
Can be seen with recent history of measles (last several weeks to months), coupled with myelin basic protein found in CSF with absence of infectious virus.
What are symptoms of measles-induced acute disseminated encephalomyelitis?
motor and sensory defects, ataxia, mental status change, myelin basic protein found in CSF.
What age of contraction of measles puts children at greater risk for contracting subacute sclerosing panencephalitis?
Before 2 years old
Describe subacute sclerosing panencephalitis disease process?
Measles virus infects neurons and spreads slowly between other neurons causing them to fuse. Symptoms don’t show up until 10-15 years later, and by that time the patient only has 1-3 years of life
What are the different kinds of picornaviruses?
poliovirus, coxsackievirus A and B, echovirus, enterovirus
What kind of viruses are picornaviruses (poliovirus, coxsackie, echo, entero)
ssRNA (+) group IV
What kind of viruses spread from arthropod vectors?
Arboviruses
What kind of arboviruses cause encephalitis?
West nile, La Crosse encephalitis virus, St. Louis Encephalitis virus, Powassan Virus
