Chapter 23: Edema, herniation and hydrocephalus Flashcards
Within how many hours can irreversible hypoxic-ischemia be neuronal injury evident on hematoxylin and eosin staining?
12h
Hoe will irreversible hypoxic-ischemia appear?
There is shrinkage of the cell body, pyknosis of the nucleus, disappearance of the nucleolus, loss of Nissl substance, and intense eosinophilia of the cytoplasm (“red neurons”)
What does axonal injury lead to?
cell body enlargement and rounding, peripheral displacement of the nucleus, enlargement of the nucleolus, and peripheral dispersion of Nissl substance (central chromatolysis)
Many neurodegenerative diseases are associated with specific intracellular inclusions, name some examples
e.g., Lewy bodies in Parkinson disease and tangles in Alzheimer disease
Can pathogenic viruses also from inclusions in infected neurons/other cells?
Yes
In some neurodegenerative diseases, neuronal processes become thickened and tortuous. How is this termed?
Dystrophic neurites
Astrocytes are the principal cells responsible for repair and scar formation in the brain. How is this process called?
Gliosis
How do astrocytes respond to injury?
They unergo hypertrophy and hyperplasia. The nucleus enlarges and becomes vesicular, and the nucleolus becomes prominent. The cytoplasm expands and takes on a bright pink hue, and the cell extends multiple stout, ramifying processes (called gemistocytic astrocyte)
How do oligodendrocytes respond to injury?
Oligodendrocytes, which produce myelin, exhibit a limited spectrum of specific morphologic changes in response to various injuries. In progressive multifocal leukoencephalopathy, viral inclusions can be seen in oligodendrocytes, with a smudgy, homogeneous-appearing enlarged nucleus.
What will microglial cells do when injured?
When activated by tissue injury, infection, or trauma, they proliferate and become more prominent histologically. Microglial cells take on the appearance of activated macrophages in areas of demyelination, organizing infarct, or hemorrhage; in other settings such as infections, they develop elongated nuclei (rod cells)
How are aggregates of elongated microglial cells at sites of tissue injury termed?
Microglial nodules (similar collections can be found congregating around and phagocytosing injured neurons (neuronophagia))
Substantial increases in the intracranial pressure compromise the ability of the cardiovascular system to deliver blood to the brain, resulting in decreased brain perfusion, with serious or fatal consequences. What are disorders that may cause a dangerous increase in the volume of intracranial contents?
Cerebral edema, hydrocephalus, hemorrhages, ischemia, and mass lesions such as tumors.
What is cerebral edema?
Cerebral edema is the accumulation of excess fluid within the brain parenchyma
What are the two types of cerebral edema?
- Vasogenic edema
* Cytotoxic edema
How does vasogenic and cytotoxic edema occur?
- Vasogenic edema occurs when the integrity of the normal blood-brain barrier is disrupted, allowing fluid to shift from the vascular compartment into the extracellular spaces of the brain. Vasogenic edema can be localized or generalized.
- Cytotoxic edema is an increase in intracellular fluid secondary to neuronal and glial cell injury, as might follow generalized hypoxic or ischemic insult or exposure to certain toxins.
