CNS Infections- Viral – Flashcards
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| Name 3 ways in which viruses cross the blood brain barrier: |
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| Growing across it Being passively transported across it in intracellular vacuoles Being carried across by WBCs |
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| What is the receptor for measles? |
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| CD46 |
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| What is the receptor for polio? |
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| CD155PVR |
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| What is the receptor for HSV? |
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| Heparin sulfate, TNF receptor |
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| What is the receptor for rabies? |
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| AChR, NCAM |
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| What is the receptor for HIV? |
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| CD4+CCR5 or CXCR4 |
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| What is hematogenous entry and what two types of viruses can do this? |
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| Directly into blood stream Arboviruses- mosquito injection Rabies- from a bite |
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| What is neural entry into the CNS, and what viruses do this? |
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| Spread from distal neural structures to CNS- Rabies, HSV, VZV Travel up ganglia |
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| What are the symptoms of frontal lobe abscess? |
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| Frontal sinusitis Headache Memory defects Attention loss Diminished intelligence |
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| What are the symptoms of temporal lobe encephalitis? |
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| Personality changes, visual field defects, hemiparesis (with large lesion), focal seizures |
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| What are the symptoms of basilar meningitis? |
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| Headache- suboccipital Neck stiffness Diplopia Cranial Nerve palsy |
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| What are 3 important aspects of the immune response to CNS pathogens? |
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| -inflammation->edema->tissue death -decreased capillary perfusion to brain -neurological symptoms |
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| What is the main class of enteroviruses, and how are they spread? |
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| Picornaviridae- SMALL RNA VIRUSES- fecal-oral transmission without symptoms of diarrhea |
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| What changes do we see in CSF in bacterial infection? |
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| Highly elevated PMNs Protein above 100 Glucose less than 45 |
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| What changes do we see in CSF in viral infection? |
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| Presence of lymphocytes/monocytes Protein 50-100 Normal Glucose (Esper said differently) |
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| What are the classic symptoms of viral meningitis? |
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| Fever, nuchal rigidity, photophobia, headache -irritability, nausea/vomiting, rash, weakness x 18-36 hours |
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| How long does viral meningitis usually take to clear? |
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| Self limiting withing 7-10 days |
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| What virus causes Hand Foot and Mouth disease? |
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| Coxsackie A |
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| What virus causes viral myocarditis? |
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| Coxsackie B |
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| What class of virus is polio? Describe it? |
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| Enterovirus + stranded RNA, non-enveloped Spread fecal-oral |
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| What viruses are estimated to cause >85% of all meningitisWhen are we more likely to see these cases? |
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| Non-polio enteroviruses Warmer months Think coxsackie A and B |
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| What are some symptoms associated with enterovirus meningitis (besides the main meningitis symptoms)? |
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| Pharyngitis, pleurodyna (pain in pleura), rash, pericarditis |
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| Describe Arboviruses generally and what they cause: |
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| Postive stranded enveloped RNA viruses Mosquito vector borne Cause ENCEPHALITIS (and sometimes meningitis) |
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| What is the most common arbovirus in the US? |
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| Saint Louis Encephalitis (SLE) |
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| What is the most common arbovirus worldwide? |
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| Japanese B |
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| What is the most common clinical manifestation of arbovirus infection? |
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| Meningoencephalitis instead of pure aseptic meningitis |
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| Why are seizures more common in arbovirus infection? |
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| Because they cause encephalitis too |
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| Describe mumps and its most important permanent effect: |
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| Mumps- negative stranded RNA virus- helical- ENVELOPED Meningitis is a common complication Causes Bilateral Parotitis (chipmunk cheeks) CAN CAUSE STERILITY IN MALES (orchitis) |
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| What virus is the leading cause of encephalitis? |
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| HSV-1 |
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| Which herpes is responsible for genital infections and neonatal meningitis? |
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| HSV-2 |
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| Describe the structure of herpes viridae: |
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| DNA virus; Icosahedral; ENVELOPED |
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| When is VZV CNS infection most common? |
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| Zoster REACTIVATION |
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| What drug should be given immediately upon suspicion of herpes viral infection? |
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| Acyclovir IV |
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| What are two ways in which viral encephalitis can be prevented? |
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| Mosquito eradication Sanitation |
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| Your patient presents with obvious infectious lesions of the temporal lobes and obvious visible vesicular outbreak on their face. What is your best guess for the causative agent? |
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| HSV |
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| Your patient presents with a rash and encephalitis. You notice the rash covers a distinctive/definable region. What is your best guess for the causative agent? |
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| VZV- shingles |
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| Your patient presents with a bite and neurological symptoms. What is your best guess for a causative agent? You slay the offending animal and look at its brains. What do you find? |
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| Rabies NEGRI BODIES |
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| When is a patient most likely to acquire herpes encephalitis? |
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| On REACTIVATION of HSV-1 |
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| Where does HSV-1 reactivate and where does it infect? |
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| Usually reactivation in the trigeminal ganglia Infects temporal lobe |
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| What characterizes an "intermediate" host? |
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| Lower viral titers, difficult to spread A "dead end" for the virus |
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| Where on earth would you find arboviruses in their highest titre form(tricky question) |
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| Mosquito salivary glands |
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| What aspect of a patient history is super important in cases of encephalitis? |
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| Travel history |
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| Describe the structure of the rabies virus: |
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| Negative stranded RNA virus HELICAL, ENVELOPED BULLET SHAPED |
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| What does rabies cause? |
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| Acute, progressive, incurable and DEADLY encephalitis |
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| What 4 animals most commonly transmit rabies in the US? Worldwide? |
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| Racoons, bats, foxes, skunks Worldwide= dogs |
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| How long is the incubation period for rabies? |
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| 1-3 months |
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| How does rabies travel in the CNS? |
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| RETROGRADE TRANSPORT |
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| Describe the path of travel of the rabies virus in an infected person: |
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| From the brain, the virus returns to the periphery, to the salivary glands (which are highly innervated) |
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| What are the symptoms of rabies? |
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| Fever, chills, headache, difficulty swallowing, HYDROPHOBIA Hallucination, disorientation, paralysis, coma, death |
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| Describe the prodrome of rabies: |
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| Flu-like |
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| How does rabies eventually kill the patient? |
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| Cardiac or respiratory arrest |
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| How is rabies diagnosed? |
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| Perivascular cuffing Skin biopsy, corneal impression, brain biopsy with PCR/IF NEGRI BODIES |
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| How is rabies treated? |
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| Clean the wound, VACCINATION (only time we vaccinate after exposure) Half in the wound, half IM Confirm if animal is rabid |
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| Describe the structure of HIV: |
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| Positive stranded RNA RETROVIRUS Enveloped |
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| Describe the course of HIV encephalitis |
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| Invades CNS shortly after initial infection- pleocytosis in CSF, mild meningitis like illness Later subacute encephalitis with dementia |
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| Describe the pathology of HIV related dementia: |
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| Brain shrunken with enlarged ventricles Vacuolization of myelin tracts Virus infects the macrophages (microglia) in the CNS |
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| What does mumps encephalitis usually follow? |
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| Parotitis (7-10 days) |
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| What virus causes subacute sclerosing pan encephalitis (SSPE)? |
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| Measles |
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| What characterizes the pathology of subacute sclerosing pan encephalitis? |
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| Progressive neurological deterioration due to brain inflammation and nerve cell death |
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| What are some symptoms of SSPE? |
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| Behavior changes, intellect/memory issues, movement issues, gait problems, seizures, speech difficulty, dysphagia |
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| What causes myelitis? |
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| POLIO- replication in neurons of gray matter of brain and spinal cord FLACCID PARALYSIS without sensory loss |
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| What is affected in bulbar polio? |
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| Respiratory muscles, medulla oblongata |
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| What are the two types of polio vaccine and which can revert to virulent strain? |
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| Salk- Killed Sabin- Live- can revert Not used in US anymore |
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| What viruses that cause encephalitis can be revealed by a Tzanck test? |
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| Herpes, VZV |
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| What virus causes Progressive Multifocal Leukoencephalopathy, and in what patient population? |
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| JC Virus- immunocompromised patients |
