ICL 10.5: Cerebrovascular Pathology

Question 1

what are the 3 basic categories of stroke?

Answer 1

1. thrombosis
2. embolism
3. hemorrhage

strokes are the MOST PREVALENT of the neurological disorders

Question 2

what are the 2 processes that occur during a stroke?

Answer 2

1. hypoxia, ischemia and infarcation

2. hemorrhage

Question 3

what is a TIA?

Answer 3

TIA = transient ischemic attack

it’s a temporary deficit due to temporarily decreased perfusion –> lasts less than 24 hours

no permanent damage

high risk of stroke

Question 4

what are the top 3 causes of stroke?

Answer 4

1. brain infarction (thrombotic or embolic) –> 80%
2. intracerebral hemorrhage (usually due to hypertension) –> 10%
3. subarachnoid hemorrhage (usually due to ruptured Berry aneurism) –> 7%

Question 5

what are the nutritional requirements of the brain?

Answer 5

it needs a constant supply of oxygen and glucose

so the blood flow to your brain is constant no matter the changes in BP or ICP –> the brain autoregulates itself!

Question 6

what is hypoxia?

Answer 6

decreased amount of oxygen

Question 7

what is anoxia?

Answer 7

no oxygen

Question 8

what is ischemia?

Answer 8

a decrease in blood flow

Question 9

the odds of a patient surviving a stroke are dependent on what factors?

Answer 9

1. collateral circulation presence
2. duration of ischemia
3. magnitude and rapidity of ↓ decrease of blood flow

Question 10

what is a focal infarction?

Answer 10

when there is a cerebral blood vessel occlusion involving all or part of an arterial territory

it’s due to a focal interruption of blood supply of that artery by thrombosis, embolism, compression, trauma, etc.

the outcome is focal deficits which is a classic stroke!

Question 11

what are the 3 cerebral arteries and what are their territories?

Answer 11

1. posterior cerebral artery
2. middle cerebral artery
3. anterior cerebral artery

slide 9 go look at which territories they’re responsible for!!!

Question 12

what is global ischemia?

Answer 12

a generalized reduction in cerebral blood flow usually due to either cardiac arrest, shock or severe hypotension –> essentially you’re cutting off blood to the entire brain

when it’s severe it’s known as diffuse ischemic/hypoxic encephalopathy and can cause widespread neuronal death

Question 13

what are the possible outcomes following a global ischemia?

Answer 13

1. mild = perhaps normal (TIA)
2. intermediate = varying degrees of cognitive impairment up to persistent vegetative state
3. severe = brain death

Question 14

what are watershed infarcts?

Answer 14

the areas between the cerebral arterial territories –> they’re border zones between arterial territories

they’re the most vulnerable to global ischemia because they’re the farthest away from a blood supply and tend to be the most effected during a global ischemia event

Question 15

which cells are the most sensitive to global ischemia and are effected first when it occurs?

Answer 15

1. CA 1 territory - hippocampus
2. purkinje fibers - cerebellum
3. cortical pyramidal neurons

Question 16

how can you tell a neuron is dead histologically?

Answer 16

neurons are usually lavender but when they’re dead they look pinky red!

slide 12

Question 17

what causes a thrombosis (that could later lead to a stroke)?*

Answer 17

atherosclerosis

there are atherosclerotic plaques usually in the carotid artery and then something happens where a piece of it breaks off which exposes the sticky stuff underneath and then you get plaque ulceration where more platelets and RBCs stick to it which extends the thrombus and makes it bigger!

Question 18

what is the most common site for a thrombosis? what will happen if there’s a thrombosis at this site?*

Answer 18

the carotid artery bifurcation

it leads to an infarction of the MCA territory

Question 19

what are the 2 most common origins of embolisms?

Answer 19

1. heart (most common source)

can be thrombotic emboli from the ventricles of heart disease patients or septic emboli in people who have vegetations on their valves like mitral valve endocarditis

2. arteries (specifically the carotid)

atheromatous plaques can break off and send emboli to the brain or you can get thromboembolism overlying the atheroma

note: other sources of emboli are from tumors, fat, amniotic fluid or air

Question 20

what are the 2 types of infarcts?

Answer 20

1. hemorrhagic (red) infarcts

2. non-hemorrhagic (pale) infarcts

Question 21

what are hemorrhagic infarcts?

Answer 21

multiple, often confluent, petechial hemorrhages

associated with embolic events

hemorrhage due to reperfusion injury –> so when the emboli dislodges and flow is restored, it causes repercussion injury

no thrombolytic therapy

slide 16

Question 22

what is a non-hemorrhagic infarct?

Answer 22

associated with thrombosis

patients are potentially eligible for thrombolytics

Question 23

hypertensive cerebrovascular disease most often effects what part of the brain?

Answer 23

basal ganglia

Question 24

what are the most important gross effects of hypertensive cerebrovascular disease?

Answer 24

1. lacunar infarcts
2. slit hemorrhages
3. hypertensive encephalopathy

Question 25

what are lacunar infarcts?

Answer 25

arteriolar sclerosis (HTN) of deep penetrating arteries cause lacunae = small cavitary infarcts from the dead brain tissue that has left holes

most commonly effect basal ganglia, white matter, brain stem

can lead to vascular (multi-infarct) dementia because they can happen more than once without detection and eventually it causes dementia

Question 26

what is a slit hemorrhage?

Answer 26

rupture of small penetrating vessels which leads to small hemorrhages that cause slit-like cavities

it’s necrosis of the brain and the brain doesn’t fix it so it’s a slit looking defect

Question 27

what is hypertensive encephalopathy?

Answer 27

there’s increased ICP and fibrinoid necrosis of the arterioles which causes diffuse cerebral dysfunction

patients will present with headache, confusion, vomiting, convulsions, coma, herniation and even death

this is a medical emergency!!

Question 28

what can cause an intracerebral hemorrhage?

Answer 28

1. hypertension
2. berry aneurysm that causes a massive subarachnoid hemorrhage
3. vascular malformations like arteriovenous malformations (most likely to bleed), venous malformations or cavernous (hem)angiomas

Question 29

what is a Berry aneurysm?

Answer 29

a pouch-like protrusion due to weakening of an arteriole wall

90% are found at major arterial branch points in anterior circulation like the anterior cerebral artery and anterior communicating artery branch point

they can rupture if they’re larger than 10 mm or there’s acute increased ICP

there’s a 50% mortality with the 1st rupture because they cause a massive subarachnoid hemorrhage so they’re really serious

Question 30

what is an arteriovenous malformation?

Answer 30

a shunt of blood directly from an artery to a vein

looks like a crazy tangle of vessels where the veins have dilated in response to exposure to arterial pressures – there’s also abnormal vessels separated by gliotic tissue

the veins are not used to dealing with the same type of blood pressure that an artery does so they are at risk for rupture and can bleed suddenly and massively

these are the most dangerous type of vascular malformation!

slide 26

Question 31

what are the types of venous malformations?

Answer 31

1. cavernous hemangioma
2. venous hemangioma

usually pretty benign but if they get big enough they can cause a problem

looks like hyalinized veins of various sizes but with NO intervening neural parenchyma

slide 27