Reasons for cerebral hypoxia

  • Functional hypoxia (anemia, high altitude)
  • Ischemia (transient or permanent)

Ischemic encephalopathy

The brain is highly dependent on blood supply.

  • Neurons are far more sensitive than glial cells to ischemia
    • Do not have glycogen stores
    • Some regions of the brain are more sensitive

Morphology

  • Swelling and cerebral edema are seen
  • Red neurons -- dying neurons
  • Liquefactive necrosis that is resolved within several weeks and replaced by gliosis

Types

  • Global
  • Focal

Global

Due to systemic hypotension (>50mmHg), seen in cardiac arrest and shock.

  • If the ischemia is short-lasting, there will be a complete recovery
  • If the ischemia is long-lasting, there will be widespread neuronal death
  • "Brain death" refers to individuals who lost all of their voluntary and reflex brain function
  • "Respirator brain" refers to the autolysis of the brain that requires a ventilator, since even the respiratory center is damaged
    • The ventilator comes after the brain damage! It does not induce brain damage
  • Watershed infarcts refer to infarcts formed in vulnerable regions, such as the border between

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