Viral CNS Infections Flashcards
Two primary ways that viruses get into the CNS?
Blood and Neurons
What is meningitis?
Inflammation of the lining of the brain
What is Encephalitis?
Inflammation of the brain tissue
What is Meningoencephalitis?
Widespread infection of the meninges and brain
What is encephalopathy? Common cause?
Damage to brain tissues: Prions
What is aseptic meningitis?
Meninges are inflamed and pyogenic bacterial source is not to blame; Infectious bug cannot be determined.
What are typical causes of aseptic meningitis? What is the most common type of viral infection?
Virus, fungi, TB; Enterovirus (90%)
Describe lumbar puncture findings of aseptic meningitis
Increased WBCs but no CSF
What Tx is used for aseptic meningitis?
Not many options but few options for herpes, fungal, and mycobacterial infections
What is Brudzinski’s sign?
Lift patient’s head upward when in the supine position and knees will bend up indicating meningitis
Describe the general progression of encephalitis
Virus (generally) -> influx of immune cells in brain -> Cerebral edema destroys neurons -> Hemorrhage
What are some urgent Syx of encephalitis?
Unresponsive/Coma, Seizures/Weakness/Paralysis, Memory Loss/Flat Affect/Withdrawal/Poor Judgement
How do you diagnose encephalitis?
Spinal tap indicates inflammation in CSF, blood (possibly), PCR for viruses; EEG/MRI/CT
What is the treatment for encephalitis? If herpes?
Supportive care/Syx relief, sedate (phenytoin), anti-inflamm/reduce edema (dexamethasone); Acyclovir
What are typical complications of meningitis? Encephalitis?
Generally benign, resolve in 2 wks; Permanent neurologic ipairments to memory, speech, vision, hearing, muscle control, or sensation
What are risk factors for viral CNS infection?
- Age (older)
- Immune status (Immunoincompetent)
- Genetics (Innate resistance of viruses)
- Exercise (may increase dissemination of virus)
What is Acute Disseminated Encephalomyelitis (ADEM)?
Postinfectious encephalitis following viral infection by 1-2 wks; possibly autoimmune etiology
What are the Alphaherpesviruses?
HSV-1/2, VZV;
When can herpetic meningitis occur?
In both primary and recurrent infections
What is the most common herpes virus that causes meningitis? What are other less frequent offenders?
HSV-1/2; VZV, CMV, EBV;
Tx for herpesvirus meningitis?
Acyclovir, valaciclovir, famciclovir
Describe the dessemination of Rabies Virus. Why is this relatively easy to treat?
Inoculated within an injured site -> Replicated w/i muscle -> Travel up nerve (slowly) -> Brain; It is so slow!
How is rabies spread? What does the virus have a tropism for?
Through salivary glands! or organ transplants!
What is the transmission of picornaviruses? Who does it affect? What are two to major Picornaviruses and which one are we currently worried about? What do we have a vaccine for?
Fecal-oral; Young children (mild disease), Old children, adult (asymp - paralytic); Polio and entero; Only to Polio
What is the general rount of dissemination of picornavirus?
Mouth -> Oral/GI Mucosa -> Blood -> Brain
What is the general circulating pattern of Arboviruses? What are the dead end hosts?
Betwixt birds and mosquitos; Horses and humans
Name 4 Togaviruses
Venezuelan equine encephalitis, Eastern Equine Encephalitis, Western Equine Encephalitis, Chikungunya virus
What are the subtypes of arbovirus we should know about?
Togavirus (WEE, VEE, EEE, Chikungunya) and Flavivirus (Japanese Encephalitis, St. Louis Encephalitis)
When during the year are arboviruses most common?
Summer months
How are arboviruses spread?
Mosquito
Describe the basic pathogenesis of prion disease
Proteins (Prions) misfold -> aggregate -> fibril formation -> Disease (May come from exogenous causes as well)
What is the major etiology of CJD? 2nd most? 3rd?=
Sporadic; Genetic; Iatrogenic
Describe the pathology found in CJD? Time frame? Prognosis?
Brain atrophy, spongiform pathology; Dementia, loss of brain fn., 6-9 months until dead;
Describe the Dx process for CJD
MRI (only suggestive), 14-3-3 protein in CSF, post-mortem analysis (autopsy general way to make Dx)
Describe precautions for prion diseases. What are the highest risk body parts?
Currently all surgical/medical equipment is thrown out/incincerated; Brain, spinal cord, eye tissue
What is a distinguishing feature of encephalitis?
Intracerebral hemorrhage
What type of viral encephalitis would a patient likely get in the summer?
Enterovirus
What is the route other than viremia where a virus may disseminate to the brain?
Retrograde transport from peripheral nerve endings or nasal mucosa!
