Stroke Pathophysiology

Question 1

Risk Factors for stroke

Answer 1

Untreated atrial fibrillation 
hypertension
smoking
hyperlipidemia
DM
TIA
Previous stroke
Heavy Alcohol consumption

Question 2

What is a TIA?

Answer 2

A small neurological event with symptoms that last less than 24 hours

Question 3

What is the common cause of a TIA?

Answer 3

embolism or stenosis-related hypoperfusion

Question 4

What percentage of people who experience a TIA will have a stroke within 5 years?

Answer 4

35%

Question 5

What percentage of strokes can be categorized as ischemic?

Answer 5

85%

Question 6

What percentage of strokes can be considered hemorrhagic?

Answer 6

12%

Question 7

Main cause of ischemia in large vessels?

Answer 7

Arteriosclerisis

Question 8

Main cause of ischemia in medium vessels?

Answer 8

Embolic (24%)

Question 9

Main cause of ischemia in small vessels?

Answer 9

Lacunar

Question 10

Main cause of ischemia in the microcirculation?

Answer 10

amyloid deposits

Question 11

Main cause of ischemia in border zone?

Answer 11

hypoperfusion

Question 12

two main causes of hemmorrhagic stroke?

Answer 12

subarachnoid hemmorhage (3% of total)
Intracerebral hemorrhage (9% of total)

Question 13

What branch of cerebral circulation is the cause of 90% of all strokes?

Answer 13

Middle Cerebral Artery

Question 14

Biggest cause of stroke in america?

Answer 14

Untreated atrial fibrillation

Question 15

What effect does rate of an ischemic stroke have on outcome?

Answer 15

The brain tolerates a shorter ischemic incident better than a longer incident. However an ischemic event that develops slowly over a long period of time has a chance for collateral circulation to develop

Question 16

How does coagulation affect progression/extent of ischemic injury?

Answer 16

any hypercoagualbe state increases the extent and progression of micro thrombi, exacerbating vascular occlusion

Question 17

How does temperature affect progression/extent of ischemic injury?

Answer 17

Higher temperature is associated with greater ischemic injury

Question 18

How can glucose affect progression/extent of ischemic injury?

Answer 18

both hypo and hyperglycemia have negative effects on progression of ischemic injury

Question 19

Normal cerebral blood flow levels?

Answer 19

50-60 mll/100gm/minute

Question 20

What happens to the vasculature during an ischemic event?

Answer 20

In response to moderate ischemia, there is vasodialation and opening of collaterals to increase the extraction of oxygen and glucose from blood

Question 21

What happens when cerebral brain flow falls below 20 ml/100gm/min?

Answer 21

Electrical silence ensues and symaptic activity is greatly diminished in an attempt to preserve energy stores

Question 22

What is the area called when the Cerebral blood flow is below 20 ml/100gm/min?

Answer 22

the Pneumbra

Question 23

What happens when the cerebral blood flow is less than 10 ml/100gm/min?

Answer 23

irreversible neuronal injury. This area is called the ischemic core

Question 24

What is the window of opportunity?

Answer 24

Up to 3 hours after the original incident where the neurological deficits created by the ischemia can be partly or completely reversed by reperfusing the ischemic tissue.

Question 25

What kind of metabolites accumulate after neurons are injured?

Answer 25

Lactic acid, glutamate, aspartate.

Question 26

What effect do metabolites have on nearby neurons?

Answer 26

Noxious metabolites from injured neurons can injure adjacent healthy neurons

Question 27

When does brain edema peak?

Answer 27

48-72 hours post onset

Question 28

What type of infarcts are more likely to develop edema?

Answer 28

Large infarcts

Question 29

How does brain edema happen?

Answer 29

The blood brain barrier breaks down and blood vessels become leaky

Question 30

What is excitotoxicity?

Answer 30

an inflammatory cascade that eventually leads to cell death

Question 31

What is dumped into the extracellular spaces in response to ischemia and injury and what does this result in?

Answer 31

glutemate, which results in the opening of calcium channels and Ca to rush into the cell

Question 32

What does the flood of calcium cause?

Answer 32

activates a series of destructive enzymes resulting in the loss of integrity of cell membrane.

Question 33

What does the flood of Ca trigger during excitotoxicity?

Answer 33

It triggers an inflammatory cascade and eventual cell death

Question 34

What is apoptosis?

Answer 34

programmed cell death

Question 35

How long after ischemic injury do apooptotic mechanisms begin?

Answer 35

within 1 hour

Question 36

What happens to blood vessels distal to the occlusion in an ischemic injury?

Answer 36

They become fragile and injured

Question 37

What is a red infarct?

Answer 37

When the occluding embolus either lyses spontaneously or breaks apart and migrates distally, restoring CBF which can result in conversion to a hemorrhagic stroke

Question 38

What are the three factors associated with a red infarct?

Answer 38

size of infarct (bigger, greater possibility) Richness of collateral circulation (more collaterals, less chance) use of anticoagulants (increases risk)

Question 39

Where dies atherosclerosis most often happen?

Answer 39

In the bifrucation of larger vessels (carotids, veterbrals, basilar)

Question 40

What is the cascade of events on atherosclerosis that leads to a potential ischemic event?

Answer 40

``` damage to vessel wall platelets congregate thrombogenesis plaque formation thrombus and smooth muscle proliferation blockage ```

Question 41

When is blockage of a large vessel considered significant?

Answer 41

>70% blockage

Question 42

What sound can stenosis cause?

Answer 42

Bruits, a swishing sound which actually can cause more damage

Question 43

How can you assess for stenosis?

Answer 43

MRA and Doppler

Question 44

What can you use as a prophylaxsis for stenosis?

Answer 44

asprin

Question 45

What is the most common pathology that effects medium vessels?

Answer 45

Embolism, mostly affecting cerebral arteries

Question 46

What is the most common source of embolism?

Answer 46

the heart

Question 47

What is the most common cause of embolism?

Answer 47

atrial fibrillation

Question 48

What is A fib usually treated with and why?

Answer 48

Routinely treated with anticoagulation therapy because embolus formation is so common

Question 49

What is the prognosis with blockage of proximal vessel?

Answer 49

poor prognosis. can result in devastating impairments

Question 50

What is the most common cause of small vessel disease?

Answer 50

Lacunar, with changes in the intima and lipofusion deposits

Question 51

What is small vessel disease associated with?

Answer 51

hypertension and diabetes

Question 52

What areas does small vessel disease usually effect?

Answer 52

deep white matter area (including internal capsule)

Question 53

What type of deficits does small vessel disease usually produce?

Answer 53

isolated deficits

Question 54

What is the most common pathology seen in microvessel disease?

Answer 54

Amyloid deposits in arterioles and capillaries

Question 55

In what patients is microirculation disease most commonly present?

Answer 55

Patients with dementia or parkinsons

Question 56

What is a hypoperfusion stroke also called?

Answer 56

Watershed or borderzone stroke

Question 57

What is a hypoperfusion stroke?

Answer 57

Happens with pump failure (either MO or major blood loss)

Question 58

What is affected with a hypoperfusion stroke?

Answer 58

distal territory of each cerebral artery. | shoulder>leg>hand/face

Question 59

What are three treatments for an ischemic stroke?

Answer 59

tPA Stents Intra-arterial clot retrieval

Question 60

What is the timeframe when you can safely administer tPA?

Answer 60

up to 3 hours of witnessed stroke

Question 61

What is the risk of tPA?

Answer 61

conversion to hemorrhage

Question 62

What are the two types of aneurysms?

Answer 62

Berry | Charcot Bouchard

Question 63

What is a Berry?

Answer 63

Congenital weakness of vessel wall at branching pont

Question 64

WHere do most Berry aneurysms happen?

Answer 64

85% form on the anterior halfo f the circle of willis (subarachnoid)

Question 65

Where is a Charcot Bouchard aneurysm found?

Answer 65

found on penetrating vessels (inside brain)

Question 66

What type of hemorrhage does a burst aneurysm (Charcot Bouchard) produce?

Answer 66

primary intracerebral hemorrhage

Question 67

What is the prognosis if a burst hemorrhage is resorbed?

Answer 67

prognosis may be good. Usually better than the prognosis of ischemic stroke of same magnitude

Question 68

What affect does blood have on the brain?

Answer 68

It is damaging due to the iron in blood

Question 69

What usually causes a subarachnoid hemorrhage?

Answer 69

Cerebral artery on surface of brain

Question 70

What is a subarachnoid hemorrhage usually described as?

Answer 70

Worst headache of my life

Question 71

What are the two methods of treating aneurysms?

Answer 71

Coils or clips

Question 72

What are the two clinical scales to evaluate hemorrhages?

Answer 72

Hunt and hess-based on symptoms and function | Fischer-based on imaging

Question 73

What is an intraparenachymal hemorrhage?

Answer 73

When there is a bleed into substance of brain

Question 74

What is an A-V malformation?

Answer 74

Direct connect between arteriole and venule which increases risk for hemorrhage because of increased pressure on veins

Question 75

What is a dissecting aneurysm the result of?

Answer 75

Results from trauma to the vessell wall ie whiplash, coughing, wrestling, strangulation

Question 76

Where does the bleeding occur with a dissecting aneurysm?

Answer 76

between the layers of the arterial wall

Question 77

What affect does the clot have after a dissecting aneurysm?

Answer 77

It occupies space and potentially occludes the lumen of the vessel.