Week 5: infectious diseases of the CNS (Commins and Landolph) Flashcards
List three symptoms or signs of acute meningitis.
- fever
- headache
- altered mental status
- lethargy
- signs of meningeal irritation, e.g. neck stiffness
List 3 complications of acute bacterial meningitis
- edema of the brain
- arteritis and phlebitis result in vascular thrombosis
- hemorrhagic necrosis due to arterial or venous occlusion
- pus accumulation at base of brain and in sulci, bathing cranial nerves, can result in permanent functional disturbances such as ocular palsies and deafness
What is the likely clinical outcome of acute viral meningitis and what type of inflammatory cells would you see? Where would they be located?
- self limited
- benigh
- resolves without sequelae
What is the clinical signs/symptoms of chronic meningitis? List the most common etiological agents, and one common long term sequelae. What type of inflammatory response would you see in histology?
- symptoms: fever headache, stiff neck, mental status change, cranial nerve deficits,
- causes: TB and cryptococcus (in US)
- generally no sequelae
- histology: epitheliod histiocytes and giant cells surrounded by lymphocytes in TB, granulomatous response in cryptococcus also that is similar to TB
How does acute bacterial meningitis differ from a bacterial abscess in terms of clinical presentation?
Clincal:
-headache and fever
-confusion, possible aphasia, IV drug use
-mild papilledema
Other:
-abscesses require dead brain tissue to get a start, often associated with endocarditis causing emboli
-most cerebral abscesses present as masses
-abscess has a contrast enhancing ring on imaging
For acute viral encephalitis/encephalomyelitis, list 3 major symptoms, 4 main pathologic features, and 3 etiologic agents.
Symptoms
-tropism
-latency
-headache, fever, mental status change,
Path features
-perivascular lymphocytes
-microglial activation with microglial nodules
-neuronophagia (activated microglia and PMNs and lymphocytes surround sick and dying neuron)
Viral agents: HIV, CMV, HSV, arboviruses, polio, rabies
What is a Negri body?
- viral inclusion (preference for Purkinje cell) in Rabies
- sharply defined, oval, eosinophic cytoplasmic inclusions
Is aspergillus an opportunistic infection? why does it appear as multiple soft areas with red brown discoloration on gross examination of an affected brain?
- Affects immunosuppressed, esp transplant patients
- necrosis and acute inflammation
- affinity for blood vessels-destroys and has surrounding hemorrhage and necrosis
Is cystercercosis an opportunistic infection? How does a human get it? what is a typical symptom?
=pork tapeworm
- not opportunistic
- from eating ova from recalling contaminated water or food
- symptoms: seizures, mass effects, obstruction of CSF, periventricular cystic lesions,
- cysts usually found in gray mater, meninges, or ventricular system
- illicit inflammatory reaction, develop granulation tissue, infection may become symptomatic when parasite dies
Define tropism of the polio virus in the CNS
- acute stage: infiltrates anterior horns of the spinal corn
- selectively infects motor neurons in spinal cord and brain stem, rarely in cortex
How do people contract an arbovirus? Although variable, what are the 3 most typical histopathological features seen in the brain at autopsy of someone who dies of an arbo virus encephalitis? List 2 etiologic agents of subacute or chronic viral encephalitis.
- virus alternates between mammalian or avian host and an insect vector
- pathology: affects gray matter, no viral inclusions, looks like nonspecific acute viral encephalitis
- causes of subacute/chronic viral encephalitis: measles, JC virus causing PML, HTLV, HIV,
How has effective antiretroviral treatment modified the natural history of HIV int rems of patient longevity, incidence of opportunistic infections, prevalence, and severity of neurocognitive dysfunction?
- greatly reduced opportunistic infections
- milder neurocognitive problems
What is HIV encephalitis? What is it look like histologically?
- HIV infects the brain directly via migration of infected monocytes, passes no to microglia
- inflammatory mediators and neurotoxic viral proteins cause white matter and neuronal damage
- histology: multinucleate giant cells, microglial nodules
What are the gross and histopathologic features of PML and how are they caused by the tropism of JC virus?
- multifocal areas of softening, discoloration, and crumbling of white matter
- staining for myelin with Luxol blue shows destruction of myelin
- infected oligodendroglial enlarged with inclusions
List 3 opportunistic infections affecting the CNS in AIDS.
-CMV, toxoplasmosis, PML, mycobcteria
List 3 major ways a person can get a human spongiform encephalopathy.
- transmitted through ingestion
- inoculation of infected tissue
- familial, e.g. sporadic CJD
Why do you not see much inflammation on histologic exam of a brain with a spongiform encephalopathy?
-there is no infectious agent involved
Explain how spongiform encephalopathies differ from viral encephalitis in terms of: how they are acquired, latency, causative agents.
- caused by prions, misfiled protein
- long incubation periods but rapidly progression dementia