Term
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Definition
Increase in size & weight; abnl influx of fluid from intravascular --> interstitial, extracellular of CNS parenchyma, esp. white matter |
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Term
What are some gross features of Cerebral Edema? |
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Definition
- Swelling and flattening of the gyri
- compression of adjacent sulci
- compression of ventricles by swollen white matter
- effacement of they gray-white boundaries
- midline shift
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Term
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Definition
| unilateral swelling --> swelling of cerebral hemisphere --> displacement of interhemispheric midline toward contralateral side --> called midline shift |
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Term
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Definition
| Injury to the endothelial cells of the microvasculature w/ opening of the endothelial junctions --> abnl vascular permeability --> fluid to white matter |
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Term
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Definition
Using intralvital dyes (e.g. methylene blue) it was found that these circulate throughout the whole body except the CNS. |
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Term
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Definition
The fxn of the BBB that prevents harmful/beneficial (toxins/antibiotics) substances into the CNS parenchyma |
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Term
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Definition
Tight endothelial junctions are the cellular and anatomic basis of the BBB. |
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Term
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Definition
Intracellular edema in response to toxic-metabolic dzs w/ involvement of the gray matter, where neurons and glial swell |
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Term
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Definition
| Stretching of the ependymal cells lining dilated ventricles w/ increased intraventricular pressure --> cell margin open --> CSF enters adjacent CNS parenchyma |
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Term
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Definition
When the degress of swelling reaches an order of magnitude exceeding the intracranial volume, herniation of certain structures through adjacent potential spaces occur. |
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Term
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Definition
Subfalcine Herniation
(black arrow) |
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Term
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Definition
Lateral displacement of the cingulate gyrus through the subfalcine space, beneath the free margin of the falx. |
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Term
Which artery is compressed in a subfalcine herniation? |
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Definition
Anterior Cerebral Artery (ACA) |
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Term
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Definition
a. subfalcine herniation
b. uncal herniation
e. transtentorial herniation |
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Term
Transtentorial Herniation |
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Definition
The hippocampal gyrus, w/ anterior portion: uncus, herniates through the tentorial notch (horiz. layer of dura separating the middle from posterior fossa).
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Term
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Definition
In mild degrees of swelling only anterior portion of the hippocampal gyrus: UNCUS, adjacent to tentorial notch herniates. |
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Term
What two structures near tentorial notch may be compressed in a transtentorial herniation? |
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Definition
Oculomotor Nerve (III) and Posterior Cerebral Artery (PCA) |
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Term
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Definition
When CN III is compressed causing paralysis of parasympathetic tone and dominance of sympathetic impulses --> fixed, dilated pupil on the ipsilateral side
*As seen in transtentorial herniation |
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Term
What artery is compressed in transtentorial herniation and what is the resulting Phys. Dx sign? |
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Definition
| compression of PCA --> hemorrhagic infarction in mesial-inferior surface of temporal and occipital lobes assoc. w/ visual cortex --> contralateral hemianopsia w/ sparing of the fovea centralis |
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Term
Kernohan's Notch Phenomenon |
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Definition
transtentorial herniation --> ipsilateral injured cerebral hemisphere w/ displacement and compression of the contralateral cerebral peduncle of the midbrain against the contralateral free margin of the tentorium. |
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Term
What does the Kernohan's Notch Phenomenon result in? |
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Definition
| It leads to an ipsilateral hemiparesis due to the compression of corticospinal tract fibers descending from the motor cortex of the contralateral hemisphere. |
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Term
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Definition
Cerebellar tonsils are forced through the bony aperture of the foramen magnum at the base of the skull. |
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Term
What is a life-treathening complication that happens in tonsillar herniation? |
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Definition
compression of the adjacent cardio-respiratory centers in the medulla --> death. |
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Term
Central (Axial) Herniation |
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Definition
severe cerebral edema --> Brainstem is forced downward along its own axis. |
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Term
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Definition
@ level of midbrain and upper pons when brainstem is moving downward and basilar artery deep penetrating branches are ripped out of the parenchyma |
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Term
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Definition
| herniation through unnatural aperture or defect in the convexity of the skull due to trauma (e.g. gunshot). The swollen cerebral cortex and subjacent CNS parenchyma extrudes through this artifical aperture in the shape of a mushroom. |
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Term
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Definition
Abnl. dilated ventricles due to abnl accumulation of CSF derived from the intraventricular choroid plexus. |
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Term
Non-Communicating Hydrocephalus |
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Definition
blockage of the ventricular system @ some point btwn. the foramen of Monro and the 4th ventricles |
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Term
Communicating Hydrocephalus |
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Definition
| Abnormality/block in the subarachnoid space, distal to the 4th ventricle foramina, leading to the delayed absorption of the CSF. |
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Term
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Definition
Results from the elongation and herniation of cerebellar tonsils through foramen magnum, thereby blocking CSF flow. |
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Term
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Definition
| failure of foramina of Luschka and Magendie to open --> dilation of 4th ventricle, agenesis of cerebellar vermis, and posterior fossa cyst. |
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