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28 Cards in this Set
- Front
- Back
Different causes of hypoxia
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Low level of oxygen of blood (CO poisoning, drowning)
Low blood flow (aka ischemia) Oxygen utilization by tissue is impaired (cyanide poisoning) |
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Low blood flow
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Ischemia; causes more damage than hypoxia; no outflow of metabolites
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Global ischemia is defined as?
Where is brain damage most severe? |
systolic pressure <50 mmHg (d/t shock, heart attack, shock)
Brain damage is most severe in watershed areas; if severe enough vegetative state or brain death may occur |
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Focal ischemia is typically d/t?
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arterial stenosis, thrombosis, atheroemboli, or thromboemboli
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Where are the watershed areas?
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Between ACA and MCA
Between MCA and PCA |
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What are the selective vulnerable regions Cells and regions?
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Cells: Neurons>Oligodendroytes>astrocytes
Regions: Hippocampus (CA1 sector)>lamina 3 and 5 of cortex>Purkinje cells in cerebellum |
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What determines the selective vulnerability?
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Variable oxygen/energy requirements of different neurons and neuronal populations
Glutamate receptor densities-->glutamate is neurotoxic when present in excess, as occurs in hypoxic/ischemic brain damage |
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Acutely hypoxic/ischemic neurons histological appearance?
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"red is dead"
shrunked and dark nucleus, no nucleolus visible Red cytoplasm (no Nissl substance) |
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Pathology?
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Hippocampal infarct; loss of neurons in the CA1 sector of the hippocampus d/t selective vulnerability
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Most common sites of thrombosis (atherosclerosis)
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Carotid bifurcation
Origin of MCA origin or end of basilar artery |
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Common sources of Emboli?
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Cardiac: Mural thrombus-->left atrium or ventricle (d/t afib, MI, valve disease)
Non-Cardiac Source-->Atheroma (plaques in carotid aa.) Fat, neoplasm, air |
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What is the most frequent vessel affected by emboli?
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Middle cerebral artery is most frequent vessel affected by emboli
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Hyaline arhteriolosclerosis caused by hypertension and diabetes mellitus?
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Lacunar infarcts/slit hemorrhages
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Chronic inflammation, fibrinoid necrosis of the wall; multinucleated giant cells and wall destruction
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Primary angiitis (vasculitis) of CNS
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Acute, subacute, and chronic gross morphology of infarct
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Actue-->up to 48 hours: soft, swollen, gray white distinction blurred
Subacute: up to 2-3 weeks: liquefactive necrosis Chronic: several months: CAVITATED, all dead tissue removed |
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Acute, subacute, and chronic microscopic morphology of infarct
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Acute: red neurons pallor, up to 48 hours-->neutrophils
Subacute: macrophages, necrotic tissue, reactive astrocytes, vascular proliferation (picture) Chronic: several months: cavity with GLIAL SCAR |
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Pathology?
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Chronic infarct
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Typical locations of venous thrombosis?
D/t? |
Usually superior sagittal sinus or lateral sinuses
Results in parasaggital hemorrhagic infarct Infection, injury, neoplasm, surgery Pregnancy, oral contraceptives, hematologic abnormalities, dehydration and malignancy |
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Most common cause of intracerebral hemorrhage (ICH)
Common locations? |
Hypertension
Putamen, thalamus, pons, cerebellum |
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Weakens the arteriole and predisposes to rupture?
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Hyaline arteriolosclerosis
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What age group presents with arteriovenous malformations? (Tangled network of vessels with arteriovenous shunt)
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M>F
Presentation between 10-30 years Most often distribution of MCA |
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Capillary telangectasia: location? bleed? Intervening brain tissue?
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Pons
DONT usually bleed Capillary telangiectasia |
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Cavernous angioma: location? bleed? Intervening brain tissue?
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Cerebellum, pons, white matter
Evidence of prior bleeding (greatly enlarged blood vessels are evidence of prior hemorrhage) NO intervening brain tissue |
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Lobar hemorrhage causes (closer to the surface of the brain)
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Neoplasms, drug abuse, vasculitis, hemorrhagic diathesis, amyloid angiopathy
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The work headache ever!
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Saccular (Berry) aneurysims-->subarachnoid hemorrhage; mosly by the ACA/ant comm artery
Increased risk with HTN, smoking, AVM DEFECT in media is CONGENITAL |
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Strokes that are in large vessels or at the end branches
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"pump" Cardioembolism stroke
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Hypoperfusion if no flow?
Low flow? |
NO flow=cortical laminar necrosis
Low flow=watershed injury |
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Sites for lacunes and hemorrhages
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Basal Ganglia, pons, thalamus, cerebellum
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