Cerebrovascular disease Flashcards
How long does it take for ischemia to cause irreversible brain damage?
6-8 minutes
List the CNS cells in order of susceptibility to ischemia from most sensitive to least sensitive
Neurons > oligodendrocytes > endothelial cells > astrocytes
What specific brain regions are particularly susceptible to ischemia?
Pyramidal neurons in CA1 hippocampus
Purkinje cells of the cerebellum
Cortical layers 3 & 5
What are the two broad categories of cerebrovascular disease?
Cerebral ischemia: can be global or focal
Intracranial hemorrhage: can be intraparenchymal or subarachnoid
What are the major etiologies of global cerebral ischemia?
Low perfusion (atherosclerosis)
Acute decrease in blood flow (cardiogenic shock)
Chronic hypoxia (anemia)
Repeated episodes of hypoglycemia (insulinoma)
What regions of the brain are affected by moderate global ischemia?
Watershed areas, which are the most distally perfused regions of the brain, which are the most vulnerable to infarction
What is the first histological change seen after global cerebral ischemia?
Red dead neurons: cytoplasmic eosinophilia, loss of Nissl substance and dark pyknotic nuclei
What is laminar necrosis?
The cerebral cortex layers 3 and 5 are susceptible to ischemia, resulting in ribbon-like laminar necrosis
What are the different types of focal ischemia?
Thrombotic, embolic, and small vessel
What is the etiology of thrombotic ischemic stroke?
Atherosclerotic plaque, most often at bifurcation of internal carotids (Flow is most turbulent at these points)
What is the etiology of embolic ischemic stroke?
Distant source of clot, most often from atrial fibrillation
Symptoms of a MCA ischemic infarct
Contralateral hemiparesis and hemisensory loss (lower face, upper extremity>lower extremity)
Contralateral visual field deficits
What is the difference between dominant and non-dominant hemispheric infarcts?
Dominant infarcts are associated with expressive aphasia
Nondominant are associated with neglect syndrome
What is the major gross difference between embolic and thrombotic infarcts?
Embolic cause red infarcts
Thrombotic cause pale infarcts
Describe how cerebral ischemic infarcts change grossly over time
6-48h: pale, swollen, indistinct border, blurred grey-white junction
2d-3wk: gelatinous, distinct border, liquefaction
>3wks: cystic, secondary degeneration
Describe how cerebral ischemic infarcts change microscopically over time
6-12h: red neurons, pallor 1-3d: neutrophils 4-7d: macrophages 7-14d: vascular proliferation >3wks: astrocytic gliosis, residual macrophages
Typical appearance of an embolic infarct
Most often MCA
Smaller than thrombotic, centered at junction between gray and white matter
Most common location of lacunar infarct
basal ganglia, thalamus, pons and subcortical white matter