Vascular pathology of the CNS--Parks Flashcards
(26 cards)
What is another name for a stroke? 2 types?
cerebral vascular accident (CVA) OR focal cerebral ischemia
ischemic: thrombotic, embolic
hemorrhagic: vascular rupture
Aside from stroke, what are other important forms of vascular pathology in the CNS?
global cerebral ischemia
AV malformations
aneurysms
What exactly is an ischemic stroke?
occurs when oxygen rich blood flow to the brain is restricted by a blood clot or other blockage
Tell the story. Hear a bruit over the carotid artery during physical exam. Within several days a patient has had a stroke. Why?
Bruit indicates possible carotid artery stenosis due to an atherosclerotic plaque.
Even if carotid artery isn’t completely occluded, parts of this thrombus can break off & lodge as an embolus in smaller cerebral vessels, such as the MCA. Ischemic infarct follows.
What is a common area for large vessel thrombi to form?
at bifurcation of vessels
Ex: bifurcation of the common carotid into the internal & external carotid arteries.
atherosclerotic plaque possible.
Aside from a fragment of atherosclerotic plaque leaving a thrombus as an embolus to cerebral vessels…what else can cause an embolic ischemic stroke from an atherosclerotic plaque?
a narrowed lumen can cause turbulent flow
somehow this can cause platelet aggregation that can break off into an embolus that lodges in smaller cerebral vessels downstream.
What is one of the risks of catheterizing a patient with atherosclerotic plaques?
just be catheterizing them you could break off parts of the plaque & cause an emboli–ischemic stroke
Patient presents with motor deficits in right arm. Where is the stroke?
probably in a lenticulostriate artery supplying the internal capsule–motor function. could be thrombus or embolus
What would be the clinical symptoms of a stroke @ the trifurcation of the middle cerebral artery?
cortical infarcts with motor & sensory loss & aphasia
What would you see on autopsy (axial section of the brain) of a patient with an MCA occlusion via thrombosis-atherosclerotic plaque?
large infarct of one hemisphere
swelling
focal dusky discoloration
What’s the deal with angiograms? What might you see?
performed by radiologists, they insert a catheter to view vessels
can see narrowing of vessels, suggestive of plaques
Why is it that old age is a risk factor for strokes?
b/c it takes time to develop atherosclerotic plaques
What is a high risk plaque?
unstable plaque, lipid rich with a thin fibrous capsule
it can rupture & you can get complete occlusion of the blood vessel (localized thrombosis)
stroke!
What is the treatment of stroke?
if ischemic, TPA if within 4 hour time limit
How does neuronal communication normally work (apart from ischemia)?
impulse travels down to presynaptic terminal
causes release of glutamate synaptic vesicle
glutamate activates NMDA receptors on next neuron.
Calcium & sodium are released into neuron w/ a short burst.
Glutamate is taken back up by glial cells & presynaptic terminal.
How does neuronal cell death happen in stroke?
impulse travels down presynaptic terminal. A TON of glutamate is released at once. NMDA receptors are activated on next neuron w/ uncontrollable release of calcium & sodium into cell. Calcium is damaging.
Glial cells & presynaptic terminal don’t take it back up.
Called excitotoxicity.
What happens once there is uncontrollable release of calcium into a cell in ischemic stroke or MI?
complex mechanism, including nitrogen free radicals.
If mild–apoptosis.
If extreme-necrosis.
What is the penumbra?
this is the tissue surrounding the dead tissue that can be saved w/ proper management & reperfusion. If not saved, will be gone forever.
What will the histo look like for an acute cerebral infarct?
edema from cell injury
red neurons
dead neurons & glial cells
neutrophils around blood vessels
When would a hemicranectomy be called for?
when there is such high ICP (perhaps from a stroke) that brain herniation is possible.
Which cell type do you see with a new infarct? After 10 days? Old infarct?
New infarct: neutrophils
After 10 days: macrophages–microglia
Old infarct: astrocytes (brain equivalent of fibroblasts)
What is the scarring of old inflammation called in the brain?
gliosis
What can gliosis cause?
epilepsy
can be confused with a low grade glioma by a pathologist
Which special type of necrosis do you sometimes see in the brain w/ infarction?
liquefactive necrosis–with cysts & everything. seen with ischemic infarct in CNS.
usu only see w/ infection in the body, like the lung.
