Vascular Path of the CNS - Parks Flashcards
what common bifurcating artery in the neck may occlude causing an ischemic stroke?
the carotid bifurcation
which part of an atherosclerotic plaque can break off and emobolize?
the outer, non calcified portions
What are the two common ways that common carotid stenosis can lead to embolization?
- fragment of the plaque itself breaks off and lodges in the brain
- PLT aggregates forms an embolus which lodges in the brain
Narrowing of the common carotid leads to what physical exam finding?
bruit
a thrombus or embolus will lead to (focal/global) ischemia
focal ischemia
infarcts of the internal capsule have what types of symptoms?
motor symptoms and hemiparesis
What are the common locations for focal embolus or thrombus?
carotid bifurcation
MCA
penetrating arteries
what happens to the brain that is downstream from an embolus?
it swells
What are the characteristics of a high risk plaque?
lipid rich
thin fibrous capsule
can rupture and thrombose
T/F: thrombosis due a high risk plaque rupture is an indication for the use of tPA
true
What happens when you rupture a high risk plaque?
complete occlusion of the artery
What ion enters the cell as it is dying which then leads to membrane damage, nuclear damage, and decreased ATP?
Ca
Explain how calcium enters dying neurons uncontrollably? what is this called?
EXCITATORY CYTOTOXICITY
Normally Na and Ca enter cells in small bursts due to glutamate. In stroke, surrounding neurons have released glutamate, but can’t take it back up because they’re dying, so the neurons are taking in more and more calcium from the glutamate
Mild ischemia leads to cell death via what mechanism while severe ischemia leads to cell death via….
mild: apoptosis
severe: necrosis
what type of free radicals are generated in ischemia?
nitrogen free radicals
what is the name for the tissue at risk?
penumbra
t/f: reperfusion of the penumbra will reduce the final size of the lesion
true
when looking at a histo slide of neurons from an ischemic stroke, why is there so much empty space between the neuons?
edema from cell injury
Edema post stroke peaks on what day?
2-3
edema post stroke can have a mass effect for how many days?
10
edema from a stroke can lead to what serious complication?
herniation
24-48 hours after a stroke, what type of infiltrate is present?
neutrophils
After day 10, what type of infiltrate is present in stroke tissue?
macrophages and microglia
An old infarct will see proliferation of what cell type because the brain doesn’t have fibroblasts?
astrocytes
What is the name for brain scarring?
gliosis
Gliosis become sites for future…
seizures
Cystic degeneration means that you are looking at the area of an old…
infarct
liquefactive necrosis leads to what type of degeneration?
cystic degen
why do you want to stop A fib?
it can embolize to the brain
What change to the heart valve can embolize and cause a stroke?
vegetations; they are friable
where do vegetative emboli from the heart tend to lodge in the brain?
MCA
you can find bacteria in the areas of infarct if the emboli was caused by…
infective endocarditis
when do you get global ischemia?
follows cardiac arrest where no blood is being pumped
severe hypotension in shock, aka hypovolemic shock from blood loss
or ischemic/hypoxic encephalopathy
loss of sulci on MRI is due to edema from….
global ischemia
are neurons or glial cells more sensitive to ischemia?
neurons
Describe neruonal vulnerability
neurons in different parts of the brain are more vulnerable to ischemia
What is a watershed infarct?
an infarct due to global ischemia that occurs at the distal ends of the arteries where there is the least blood flow
what are the two pathologic changes that occur in global ischemia?
watershed infarct
cortical laminar necrosis
Border zone infarcts are aka
watershed infarcts
What artery supplies the internal capsule and other deep brain structures?
the MCA
The deeper the lesion in the brain, the (blank) it is
worse
HTN will cause a hemorrhage into superficial or deep areas of the brain?
deep
HTN accelerates what process that leads to MI and stroke?
atherosclerosis
Blow out hemorrhages occur because of ….
uncontrolled HTN
what is the name for the penetrating arteries of the brain?
lenticulostriate arteries
What other organs besides the brain have small arteries coming off of a big hose?
kidneys and eye;
therefore the brain, kidneys, and eye are the most susceptible to HTN damage
Lacunar infarcts can happen as a result of….
HTN
T/F: lacunar infarcts are commonly asymptomatic
true
what is notable about the symptom presentation of lacunar infarcts?
tend to be whole-body hemiparesis; face-arm-leg or arm-leg
T/F: berry/saccular aneurysms pose no direct threat as long as they don’t rupture
true
Are berry aneurysms acquired
no, all congenital
Where do berry aneurysms commonly present in the circle of willis?
- anterior cerebral artery near anterior communicating
- MCA-either farther out or near posterior communicating
- Basilar-posterior junction
Where does the blood go when a berry aneurysm ruptures?
either over the brain or into the brain
What happens when a ruptured aneurysm bleeds over the brain?
subarachnoid hemorrhage
When aneurysms rupture, you get a ….
strok
What makes berry aneurysms worse?
HTN
What disease is associated with aneurysms?
polycystic kidney disease
The likelihood of an aneurysm to rupture is directly related to…
its size
Ateriovenous malformations can rupture and cause a stroke with the first sign often being…..
a headache
