Vascular pathology of the CNS--Parks

Question 1

What is another name for a stroke? 2 types?

Answer 1

cerebral vascular accident (CVA) OR focal cerebral ischemia

ischemic: thrombotic, embolic
hemorrhagic: vascular rupture

Question 2

Aside from stroke, what are other important forms of vascular pathology in the CNS?

Answer 2

global cerebral ischemia
AV malformations
aneurysms

Question 3

What exactly is an ischemic stroke?

Answer 3

occurs when oxygen rich blood flow to the brain is restricted by a blood clot or other blockage

Question 4

Tell the story. Hear a bruit over the carotid artery during physical exam. Within several days a patient has had a stroke. Why?

Answer 4

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.

Question 5

What is a common area for large vessel thrombi to form?

Answer 5

at bifurcation of vessels
Ex: bifurcation of the common carotid into the internal & external carotid arteries.
atherosclerotic plaque possible.

Question 6

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?

Answer 6

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.

Question 7

What is one of the risks of catheterizing a patient with atherosclerotic plaques?

Answer 7

just be catheterizing them you could break off parts of the plaque & cause an emboli–ischemic stroke

Question 8

Patient presents with motor deficits in right arm. Where is the stroke?

Answer 8

probably in a lenticulostriate artery supplying the internal capsule–motor function. could be thrombus or embolus

Question 9

What would be the clinical symptoms of a stroke @ the trifurcation of the middle cerebral artery?

Answer 9

cortical infarcts with motor & sensory loss & aphasia

Question 10

What would you see on autopsy (axial section of the brain) of a patient with an MCA occlusion via thrombosis-atherosclerotic plaque?

Answer 10

large infarct of one hemisphere
swelling
focal dusky discoloration

Question 11

What’s the deal with angiograms? What might you see?

Answer 11

performed by radiologists, they insert a catheter to view vessels
can see narrowing of vessels, suggestive of plaques

Question 12

Why is it that old age is a risk factor for strokes?

Answer 12

b/c it takes time to develop atherosclerotic plaques

Question 13

What is a high risk plaque?

Answer 13

unstable plaque, lipid rich with a thin fibrous capsule
it can rupture & you can get complete occlusion of the blood vessel (localized thrombosis)
stroke!

Question 14

What is the treatment of stroke?

Answer 14

if ischemic, TPA if within 4 hour time limit

Question 15

How does neuronal communication normally work (apart from ischemia)?

Answer 15

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.

Question 16

How does neuronal cell death happen in stroke?

Answer 16

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.

Question 17

What happens once there is uncontrollable release of calcium into a cell in ischemic stroke or MI?

Answer 17

complex mechanism, including nitrogen free radicals.
If mild–apoptosis.
If extreme-necrosis.

Question 18

What is the penumbra?

Answer 18

this is the tissue surrounding the dead tissue that can be saved w/ proper management & reperfusion. If not saved, will be gone forever.

Question 19

What will the histo look like for an acute cerebral infarct?

Answer 19

edema from cell injury
red neurons
dead neurons & glial cells
neutrophils around blood vessels

Question 20

When would a hemicranectomy be called for?

Answer 20

when there is such high ICP (perhaps from a stroke) that brain herniation is possible.

Question 21

Which cell type do you see with a new infarct? After 10 days? Old infarct?

Answer 21

New infarct: neutrophils
After 10 days: macrophages–microglia
Old infarct: astrocytes (brain equivalent of fibroblasts)

Question 22

What is the scarring of old inflammation called in the brain?

Answer 22

gliosis

Question 23

What can gliosis cause?

Answer 23

epilepsy

can be confused with a low grade glioma by a pathologist

Question 24

Which special type of necrosis do you sometimes see in the brain w/ infarction?

Answer 24

liquefactive necrosis–with cysts & everything. seen with ischemic infarct in CNS.
usu only see w/ infection in the body, like the lung.

Question 25

What is atrial fibrillation a risk factor for stroke?

Answer 25

left atrial appendage can get a clot (greater risk w/ a fib) & that can be thrown thru LV & into the aorta, up to the brain to occlude a smaller vessel.

Question 26

What are vegetations? what causes them? What are they a risk factor for?

Answer 26

Vegetations: seen on the heart valve, tannish red. not calcified.
Caused by: infective endocarditis
Risk factor for: embolic stroke. can even cause small infarcts all over w/ cystic degeneration. can find some bacteria in these cysts.