Vascular Pathology of the Brain - Parks

Question 1

What is another name for stroke?

Answer 1

Cerebral Vascular Accident

Question 2

What are some general causes of stroke?

Answer 2

1. thrombotic vessel occlusion
2. vascular rupture
3. embolic vessel occlusion

Question 3

What are some vascular pathologies of the CNS?

Answer 3

1. stroke
2. global Cerebra ischemia
3. A-V malformations
4. Aneurysms

Question 4

Describe an ischemic stroke.

Answer 4

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

Question 5

What are the 2 types of stroke?

Answer 5

1. ischemic - caused by an embolus or thrombus that blocks the flow of blood to a focal area of the brain
2. hemorrhagic - caused by the rupture of weakened/diseased blood vessels and the subsequent leaking of blood into brain tissue

Question 6

What are three common areas for blood clots leading to ischemic strokes?

Answer 6

1. the middle cerebral artery - this artery trifurcates and occlusions here lead to cortical infarcts with motor and sensory loss and often aphasia
2. the bifurcation of the carotid artery
3. Striate/penetrating branches of the internal carotid artery - causes infarcts in the internal capsule and causes a motor deficit

Question 7

Ischemic infarcts are usually what?

Answer 7

Well demarcated

Question 8

Describe two ways that the bifurcation of the carotid artery can lead to a stroke.

Answer 8

1. atherosclerotic plaque forms and a fragment breaks off and causes an occlusion further up
2. atherosclerotic plaque forms and platelets aggregate. The platelet aggregates break off and cause an occlusion further up

Question 9

What is the difference between an embolus and a thrombus?

Answer 9

A thrombus is a blood clot that forms in a vein.
An embolus is anything that travels through the blood vessels until it reaches one that is too small for it to pass through.

Question 10

What is a sign of the narrowing of the carotid artery?

Answer 10

A carotid bruit.

Question 11

What types of atherosclerotic plaques are dangerous?

Answer 11

Unstable ones. These are lipid rich with thin fibrous capsules. They can rupture and cause a thrombus and a stroke. They are more likely to be a thrombus rather than an embolus.

Question 12

What is a common treatment for a blood clot?

Answer 12

Tissue plasminogen activator or tPA.

Question 13

What comes into neurons during ischemia and triggers many processes?

Answer 13

Calcium. Increased cytosolic calcium leads to membrane damage, nuclear damage, a decrease in ATP, and cell death. If the the increase in calcium is severe then cell death occurs via necrosis and if less severe then cell death occurs via apoptosis.

Question 14

What is the role of NMDA receptors in ischemia?

Answer 14

Ischemia leads to the release of large amounts of glutamate without reuptake. These receptors allow calcium and sodium to go through into the cell uncontrolled and this causes cytotoxicity.

Question 15

After an ischemic stroke, describe the areas of the infarct.

Answer 15

1. The central core of the infarct is dead brain tissue
2. the area surrounding the dead tissue is called the penumbra and this is the tissue that is at risk and may die if there is no intervention

Question 16

What is a major goal of therapy for ischemic strokes?

Answer 16

The preservation of the penumbra or high risk areas of tissue surrounding the infarct.

Question 17

Describe a histopathologic slide of an acute cerebral infarct.

Answer 17

1. edema
2. hypereosinophilic neurons
3. perivascular, polymorphonuclear leukocytes - 24-48 afterwards neutrophils are present then later the area will have microglia and macrophages
4. an older infarct will show many astrocytes

Question 18

What is the danger of edema in acute stroke?

Answer 18

Edema leads to increased intracranial pressure which in turn leads to possible herniation

Question 19

What is gliosis?

Answer 19

Gliosis is like scarring of the brain. The brain does not have fibroblasts but it does have astrocytes. These cells will proliferate in areas of injury after the acute events.

Question 20

What other type of pathology can present after brain infarcts?

Answer 20

Liquefactive necrosis leading to cystic degeneration.

Question 21

What conditions are associated with increased chance of emboli to the brain?

Answer 21

1. A-fib - causes thrombi in the atrium

2. infective endocarditis - leads to friable vegetations which can break off and become emboli

Question 22

Describe global ischemia.

Answer 22

1. follows cardiac arrest where no blood is being pumped
2. follows severe hypotension in shock - such as hypovolemic shock from severe blood loss
3. follows ischemic/hypoxic encephalopathy - ie. during carbon monoxide poisoning

Question 23

What might you see on MRI after global ischemia?

Answer 23

1. At first the changes will not show up

2. after time you will see a ‘loss’ of sulci due to diffuse cell injury and diffuse edema

Question 24

Are some parts of the brain more susceptible to infarct than others?

Answer 24

Yes. This is because of the distribution of the vasculature.

Question 25

What are the parts of the brain that are more susceptible during global ischemia?

Answer 25

1. watershed infarcts - occurs in the superior cortical position at the distal portions of the anterior and middle cerebral arteries
2. laminar necrosis - involves short penetrating arteries
3. select neuronal systems - pyramidal cells of the Sommer sector, Purkinje cells

Question 26

Is it worse to have hemorrhages in deep areas of the brain or cortical areas?

Answer 26

Hemorrhages in deep areas of the brain are associated with a worse prognosis than cortical areas.

Question 27

What type of hemorrhage is almost always associated with hypertension?

Answer 27

A blowout hemorrhage.

Question 28

What is the association between hypertension and stroke?

Answer 28

1. HTN accelerates atherosclerosis
2. HTN increases the risk of MI
3. HTN increases the risk of blowout hemorrhages

Question 29

Describe lacunar strokes.

Answer 29

1. lenticulostriate arteries are small penetrating arteries that come off of the middle cerebral arteries.
2. These arteries are much smaller than the MCA so they are a place for emboli and they can also get aneurysms that burst
3. hemorrhages in the lenticulostriate arteries cause lacunae or small craters in blood tissue

Question 30

Why are the lenticulostriate arteries particularly vulnerable to the effects of hypertension?

Answer 30

Because they are much smaller than the MCA which they branch off of. Other areas such as the kidneys and the eyes also have this kind of vasculature that makes them vulnerable to damage mediated by HTN.

Question 31

What is another risk of hypertension?

Answer 31

HTN can irritate congenital aneurysms such as Berry aneurysms.

Question 32

What are some common places for Berry aneurysms?

Answer 32

The circle of Willis and around bifurcations.

Question 33

Berry aneurysms are associated with what disease?

Answer 33

Polycystic kidney disease.

Question 34

Describe some characteristics of Berry aneurysms.

Answer 34

1. almost always congenital
2. can expand in size
3. likelihood of rupture is associated with size
4. almost always occur in the Circle of Willis in the area of the subarachnoid space

Question 35

What is an AVM?

Answer 35

A congenital condition - arteriovenous malformation. These can rupture and cause a stroke. They also commonly cause headaches.