Diseases Patterns of the CNS

• REACTIONS OF NEURONS TO INJURY

  • Can be due to acute processes: 
  • Oxygen depletion: such as in cerebrovascular cases ( stroke) 
  • Glucose depletion (hypoglycemia) 
  • Trauma
• REACTIONS OF NEURONS TO INJURY

  • May be due to chronic processes: Abnormal protein aggregates 
  • Seen in neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, Amyotrophic Lateral Sclerosis, Lewy-Body Dementia
• Morphology (ACUTE NEURONAL INJURY): 

  • Shrinkage of cell body
  • Pyknosis 
  • Disappearance of nucleolus 
  • Loss of Nissl substance 
  • Intense eosinophilia of the cytoplasm
  • Formation of Red Neurons
• SUBACUTE AND CHRONIC NEURONAL INJURY

  • Neuronal death due to progressive disease ("degeneration") 
  • Seen in slowly evolving neurodegenerative diseases
  • Morphology: 
  • Best indicator: Cell loss due to apoptosis with reactive gliosis 
  • Gliosis: Inflammatory proliferation in response to loss of neurons and brain tissue damage