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Flashcards in Neuro Deck (229)
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61

Brain Abscess

  • destructive lesion coming from bacterial endocarditis, congenital heart disease, chronic pulmonary sepsis, or immunosuppression.
  • mainly strep and staph.
  • morphology: central region of liquefactive necrosis.  older have fibrous capsule with reactive gliosis and marked vasogenic edema.
  • presentation: progressive focal neurologic deficits and signs of ↑ ICP.
    • subdural space infected ⇒ thrombophlebitis ⇒ venous occlusion and brain infarction.

62

Tuberculous Meningitis

  • can ⇒ arachnoid fibrosis, hydrocephalus, obliterative endarteritis
  • morphology: diffuse meningoencephalitis.  subarachnoid has gelatinous or fibrinous exudate of chronic inflammatory cells.  granulomas at base of brain are rare ⇒ obliterate cisternae and encase cranial nerves.
    • arteries in subarachnoid may have obliterative endarteritis.
  • presentation: headache, malaise, mental confusion, vomiting.
    • mod CSF mononuclear cell pleocytosis, ↑ protein, mod ↓ or normal glucose.

63

Neurosyphilis

  • tertiary stage of disease, 10%.
  • ↑ risk in HIV pts.
  • meningovascular neurosyphilis = chronic meningitis associated with obliterative endarteritis.
  • paretic neurosyphilis = from brian invasion by spirochetes with neuronal loss and microglial proliferation
    • have insidious loss of mental and physical capacity with mood alterations ⇒ severe dementia.
  • tabes dorsalis = from spirochete damage to dorsal root sensory neurons ⇒ impaired joint position sense, locomotor ataxia, loss of pain with secondary skin and joint damage (Charcot joints), absent deep tendon reflexes.

64

Neuroborreliosis

  • in Lyme disease.
  • includes septic meningitis, facial nerve palsies, encephalopathy.
  • microglial proliferation and scattered organisms.

65

Arthropod-Borne Viral Encephalitis

  • inflammed meninges or spinal cord.
  • from Eastern and Wester Equine viruses, Venezuelan virus, St. Lous virus, La Crosse virus, West Nile virus.
  • all have animal hosts and mosquito or tick vector.
  • presentation: seizures, confusion, delirium, stupor or coma.

66

Hereps Simplex Virus Type I

  • inflammed meninges or spinal cord.
  • most common in kids or young adults.
  • morphology: hemorhagic, nectrotizing encephalitis of inferomedial temporal lobes and orbital gyri of frontal lobes.
    • perivascular infiltrates with Cowdry A intranuclear viral inclusion bodies in neurons and glia.
  • presentation: alterations in affect, mood, memory, and behavior.
    • protracted course = weakness, lethargy, ataxia, and seizures.

67

Herpes Simplex Virus Type II

  • severe generalized encephalitis in 50% neonates born vaginally.
  • meningitis in adults, severe hemorrhagic, necrotizing encephalitis in HIV pts.

68

Varicella Zoster (Brain)

  • shingles can cause persistent painful post-herpetic neuralgia syndrome.
  • granulomatous arteritis, or necrotizing encephalitis in immunocompromised

69

Cytomegalovirus (Brain)

  • in utero infection ⇒ periventricular necrosis, microcephaly, and periventricular calcification.
  • in AIDS = opportunistic infection ⇒ subacute encephalitis with microglial nodules or periventricular hemorrhagic necrotizing encephalitis and choroid plexus.
  • has classic CMV inclusions.

70

Poliomyelitis

  • inflammation confined to anterior horns but can extend to posterior horns.
  • meningial irritation and CSF picture of aseptic meningitis.
    • involves lower motor neurons ⇒ flaccid paralysis with hyporeflexia and 2° muscle wasting.
    • can get myocarditis, death from respiratory muscle paralysis.
  • presentationpost-polio syndrome = 25-35yrs after polio, progressive weakness associated with pain and ↓ muscle mass.

71

Rabies (Brain)

  • severe encephalitis from rabid animal or exposure to a bat without a bite.
  • over 1-3 months the virus travels up peripheral nerves ⇒ CNS excitability, hydrophobia, flaccid paralysis
  • death from respiratory center failure.
  • widespread neuronal necrosis and inflammation.
    • worst in basal ganglia, midbrain, medulla.
  • Negri bodies in hippocampal pyramidal cells and Purkinje cells.

72

HIV (Brain)

  • 10% get aseptic meningitis within 1-2 wks of primary HIV infection.
  • HIV encephalitis in symptomatic pts.
  • only microglia express CD4 and chemokine receptors for efficient HIV infection.
  • 80-90% get CNS lesions: direct viral pathogenic effects, opportunistic infections, and/or CNS lymphomas.
  • HIV-associated dementia = related to extent of activated CNS microglia.
  • morphology: chronic inflammatory reaction with widely distributed microglial nodules, multinucleated giant cells, with necrosis and gliosis.
    • most affects subcortical white matter, diencephalon, brain stem.

73

Progressive Multifocal Leukoencephalopathy

  • from oligodendrocyte infection by JC polyomavirus in immunosuppressed pts.
  • have evidence of prior JC exposure so is reexposure.  
  • develop progressive neuro manifestations from focal myelin destruction.
  • morphology: demyelinated patches, greatly enlarged oligodendrocyte nuclei with viral inclusions.  astrocytes with enlarged atypical nuclei.

74

Subacute Sclerosing Panencephalitis

  • SSPE.  progressive syndrome of cognitive decline, limb spasticity, and seizures.
  • occurs months to years after early age measles infection.  
  • presistent but nonproductive CNS infection.
  • widespread gliosis and myelin degeneration, associated with nuclear inclusions in oligodendrocytes and neurons.
  • variable inflammation with neurofibrillary tangles.

75

Fungal Meningoencephalitis

  • in immunocompromised patients with widespread hematogenous dissemination
    • Candida, Mucor, Aspergillus, Cryptococcus.
  • Histoplasma, Coccidioides, and Blastomyces involve CNS after pulmonary or cutaneous infections.
  • meningitis: by Cryptococcus.
    • fulminant and fata within 2 wks or chronic and indolent over months-yrs.
  • vasculitis: Mucor and Aspergillus.
    • vessel invasion with thrombosis and hemorrhagic infarction.
  • granulomas or abscesses with Candida and Cryptococcus.

76

Toxoplasma gondii (Brain)

  • seen in HIV pts.
  • symptoms over 1-2 wks, are focal.  
  • multiple ring-enhanced lesions.
  • abscesses with fre tachyzoites and encysted bradyzoites.
  • maternal infection can ⇒ fetal cerebritis with multifocal necrotizing lesions that calcify.

77

Naegleria (Brain)

  • causes rapidly fata necrotizing encephalitis.

78

Acanthamoeba

  • associated with chronic granulomatous meningoencephalitis

79

Prion Diseases

  • have spongiform changes (neuronal and glial intracellular vacuoles) caused by prion proteins. (PrP).
  • infectious, sporadic, or familial.  
  • Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome, fatal familial insomnia, and kuru.
  • pathogenesis: disease when becomes abnormally folded as beta-pleated sheet.
    • can induce changes in normal PrP.
  • polymorphisms at codon 129 (for methionine or valine) influence disease.
  • heterozygosity at codon 129 is protective.

80

Creutzfeldt-Jakob Disease

  • 85% sporadic.  peaks btw 60-70yrs.  
  • presentation: subtle memory and behavior changes, then rapidly progressive dementia, with involuntary jerking muscle contractions.
  • fatal.  die ~7months after symptom onset.

81

Variant Creutzfeldt-Jakob Disease

  • in young adults.
  • early behavior manifestations and slower neurologic progression.
  • linked to bovine spongiform encephalopathy.
  • extensive cortical plaques with surrounding halo of spongiform change.

82

Gerstmann-Strauss-Scheinker Syndrome

  • inherited disease with PRNP mutations.
  • morphology: spongiform transformation of cerebral cortex and deep gray matter structures (caudate and putamen).
    • advanced = severe neuronal loss, reactive gliosis, expansion of vacuolated areas into cystlike spaces (status spongiosus).
    • kuru plaques = extracellular aggregates of PrPsc proteins on congo-red and PAS-pos.
  • presentation: chronic cerebellar ataxia, then progressive dementia.
    • death a few years after symptom onset.

83

Fatal Familial Insomnia

  • PRNP mutations substitute aspartate for asparagine at 178 of PrPc.
    • mutation and methionine at 129 ⇒ FFI.  
    • valine at 129 ⇒ CJD.
  • morphology: NO spongiform changes.  neuronal loss and reactive gliosis in inferior olivary nuclei and anterior ventral and dorsomedial nuclei of thalamus.
  • presentation: sleep disturbances in initial stages.

84

Multiple Sclerosis

  • autoimmune demyelinating disorder with distinct episodes of neurologic deficit separated in time and attributable to white matter lesions that are separated in space.
  • F>M.  peak age btw childhood and 50yrs.
  • relapsing and remitting with acute deficit onset and slow partial remission.
    • relapse frequency increases over time but have steady neuro deterioration.
  • pathogenesis: cellular immune response against myelin.
    • susceptibility linked to DR2 locus of major histocompatibility complex and polymorphisms in IL-2 and IL-4 receptor genes.
    • initiated by TH1 and TH17 cells ⇒ myelin destruction.
      • TH1 ⇒IFNgamma ⇒ activate macrophages
      • TH17 ⇒ recruit leukocytes.
    • CSF has oligoclonal Ig response = B cell response.
  • morphology: plaques are sharply defined areas of gray discoloration  of white matter around ventricles.
    • active plaques have myelin breakdown, lipid-laden macrophages, and relative axonal preservation.
      • lymphocytes and mononuclear cells at plaque edges and venules.
    • inactive plaques lack inflammatory infiltrate, show gliosis.
    • axons remain but are unmyelinated.
  • presentation: unilateral vision impairment from optic neuritis.
    • cranial nerve signs, ataxia, nystagmus, internuclear ophthalmoplegia from brainstem involvement.
    • limb and trunk motor and sensory impairment, spasticity, and bladder dysfunction from spinal cord lesions.

85

Neuromyelitis Optica

  • aka Devic disease.
  • bilateral optic neuritis and spinal cord demyelinating lesions.
  • white matter lesions = necrosis with acute inflammation, vascular Ig and complement deposits.
  • Ab to aquaporins - important for astrocyte foot processes and BBB.

86

Acute Disseminated Encephalomyelitis

  • diffuse demyelinating disese after viral infection.
  • perivenular demyelination with axonal preservation, early neutrophil infiltrates then mononuclear cell inflammation and lipid-laden macrophages.
  • presentation: headache, lethargy, and coma.  no focal deficits.  20% die.

87

Acute Necrotizing Hemorrhagic Encephalomyelitis

  • fulminant, commonly fatal, demyelinating syndrome in kids and young adults after upper respiratory tract infection.  
  • small vessel destruction and disseminated CNS necrosis.
  • have perivascular demyelination with axonal preservation.  early neutrophils then mononuclar cells then lipid-laden macrophages.

88

Central Pontine Myelinosis

  • myelin damage with axonal preservation but without inflammation in basis pontis and portions of pontine tegmentum ⇒ spastic paresis.
  • associated with rapid correction of hypnatremic state.

89

Alzheimer Disease

  • begins after age 50yr.  progressive insidious impairment of higher intellectual function over 5-10yrs.
  • mostly sporadic.
  • common cause of death = intercurrent disease (pneumonia)
  • morphology: cortical atrophy with narrowed gyri and widelned sulci in frontal, temporal, and parietal lobes.  hydrocephalus ex vacuo, medial temporal structures involved early.
    • neuritic plaques and neurofibrillary tangles.
    • cerebral amyloid angiopathy (CAA) = alpha-beta amyloid deposition
    • granulovacuolar degeneration = formation of small clear intraneuronal cytoplasmic vacuoles.
    • Hirano bodies = elongated, glassy eosinophilic paracrystalline arrays of beaded filaments, mostly actin.
  • pathogenesis: AB deposition can be neurotoxic ⇒ synaptic dysfunction, inflammation
    • familial forms = mutation in APP on chromosome 21
      • Down syndrome have early onset.
      • early onset from mutations in presenilin (PS1 or PS2) ⇒ enhanced gamma-secretase activity.
      • apolipoprotein epsilon4 ⇒ ↑ risk

90

Frontotemporal Dementia with Parkinsonism Linked to Tau Mutations

  • have parkinsonian symptoms
  • mutation in MAPT (tau) gene, affects tau in microtubules.
  • morphology: frontal and temporal lobe atrophy.
    • neuronal loss, gliosis, tau-containing neurofibrillary tangles.
    • can have nigral degeneration or glial cell inclusions.