Strokes

Question 1

ischemia

Answer 1

inadequate blood supply (including O2 and glucose)

Question 2

prolonged ischemia results in ____

Answer 2

infarction (cell death)

Question 3

anoxia

Answer 3

inadequate oxygen supply

Question 4

what can cause a stroke?

Answer 4

• ischemia: result of occlusion (blocked a due to atherosclerosis or blood clot)
• hemmorrhage (bleeding a due to ruptured aneurism or hypertension)
• hypotension

Question 5

what is the cause of the majority of strokes?

Answer 5

ischemia (caused by clotting)

Question 6

what are the types of blood clots that cause ischemic stroke?

Answer 6

• thrombotic (eg. lacunar)
• embolic

Question 7

when does a thrombotic stroke usually occur?

Answer 7

when a large artery to the brain is blocked by a blood clot (thrombus) that forms as a result of atherosclerosis
(occurs at site of formation)

Question 8

atherosclerosis is a chronic inflammatory response where ____ and ____ are released

Answer 8

macrophages
neutrophils

Question 9

the immune system releases ____ in response to inflammatory mediators of atherosclerosis, which function to…

Answer 9

cytokines
attract more white blood cells and perpetuate the cycle

Question 10

in atherosclerosis, injured arterial walls fail to produce enough ____, which leads to…

Answer 10

• nitric oxide (maintains BV elasticity)
• arteries become calcified & lose elasticity

Question 11

how does a thrombus form?

Answer 11

• atherosclerosis -> macrophages & neutrophils
• immune system -> cytokines
• injured walls -> insufficient NO -> calcified aa
• arterial walls stenose -> occlusion of blood flow

Question 12

in atherosclerosis, arterial walls…

Answer 12

stenose: slowly thicken, harden & narrow until blood flow is reduced

Question 13

Lacunar stroke

Answer 13

thrombotic stroke of small branches of large vessels that supply the brain

Question 14

a lacunar stroke may cause…

Answer 14

clumsiness
weakness
emotional variability
(depending on branch affected)

Question 15

an embolic stroke is usually caused by an ____

Answer 15

embolus: a dislodged blood clot that has traveled through the blood vessels, leading to embolic stroke

Question 16

what are 4 possible causes of an embolus?

Answer 16

1. atrial fibrillation: blood pooled in atria forms clots which break off and travel to brain as emboli
2. artificial heart valves or heart valve disorders
3. heart attack or failure
4. emboli formed from fat particles, tumor cells, or air bubbles that travel through the blood stream (rare)

Question 17

in a healthy brain, neurons are protected from exposure to blood by the ____

Answer 17

blood-brain barrier

Question 18

what is the blood-brain barrier?

Answer 18

a wall of tiny vessels and astrocytic feet

Question 19

what occurs in a hemorrhagic stroke?

Answer 19

• arteries weaken & break open
• blood-brain barrier is broken
• accompanied by a catastrophic headache

Question 20

name 2 location-based categories of hemorrhagic strokes

Answer 20

• intracerebral or parenchymal (bleeding within cerebrum)
• subarachnoid (bleeding into subarachnoid space)

Question 21

what causes hemorrhagic strokes?

Answer 21

weakened arteries break open due to:
- aneurysms
- arteriovenous malformations (AVM)
- hypertension

Question 22

what is an aneurysm and how does it cause a hemorrhagic stroke?

Answer 22

• balloon-like dilations of arteries
• dome of dilation is fragile and may rupture and cause bleeding

Question 23

what is an arteriovenous malformation and how does it cause a hemorrhagic stroke?

Answer 23

• abnormal connection between arteries & veins
• if it occurs in the brain & ruptures, may cause hemorrhagic stroke

Question 24

hypertensive hemorrhages tend to be ____

Answer 24

intracerebral

Question 25

what is hypotension and how does it cause a stroke?

Answer 25

- low BP can occur from heart attack, major bleeding, major infection, surgical anesthesia, or overtreatment of high BP - extreme hypotension can reduce O2 supply to brain and cause stroke

Question 26

name the risk factors for stroke

Answer 26

- age - gender - ethnicity - geography - hypertension - atrial fibrillation - smoking - diabetes & insulin resistance - obesity & sedentary lifestyle - cholesterol & lipids - alcohol, coffee, drug abuse - genetics - heart disease & treatment - mental & emotional - migraine - homocysteine & vit B deficiency

Question 27

stroke risk factor: Age

Answer 27

- adults over 65 years most at risk, especially with 2+ risk factors - 28% victims are <65 years

Question 28

stroke risk factor: Gender

Answer 28

mortality higher in women

Question 29

stroke risk factor: Ethnicity

Answer 29

higher risk in minority groups, especially middle-aged African Americans

Question 30

stroke risk factor: Geography

Answer 30

- highest risk in Southeastern US - also high in lower Mississippi valley & Southern California

Question 31

stroke risk factor: Hypertension

Answer 31

- contributes to 70% of all strokes - wider spread between systolic & diastolic = greater risk

Question 32

stroke risk factor: Atrial Fibrillation

Answer 32

1 in 6 strokes due to A-fib

Question 33

stroke risk factor: Smoking

Answer 33

- pack a day = 2.5x greater risk as non-smokers - increases both hemorrhagic & ischemic stroke risk

Question 34

stroke risk factor: Obesity & sedentary lifestyles

Answer 34

weight centered around abdomen = high association w stroke & heart disease

Question 35

stroke risk factor: Cholesterol & other lipids

Answer 35

- HDL important for preventing strokes - hypertensive pts with overall cholesterol levels <180mg/dl = risk for hemorrhagic stroke

Question 36

stroke risk factor: Alcohol, Coffee, & Drug abuse

Answer 36

- alcohol: heavy use = higher risk of ischemic & hemorrhagic; mild/moderate = lower risk ischemic, higher risk hemorrhagic - coffee: 3+ cups/day = higher risk in older men w/hypertension - Drug abuse (ie., cocaine, methamphetamine, steroids)

Question 37

stroke risk factor: Mental & emotional factors

Answer 37

- Stress: men w/ intense response to stress, chronic or frequent stress (higher BP) = higher risk - Depression: higher risk of stroke and lower survival rates

Question 38

stroke risk factor: migraines

Answer 38

- migraine/severe headache = higher risk, especially before age 50 (diminishes with age) - oral contraceptives = higher risk in young women who have auras - taking decongestants may increase risk in those w migraines

Question 39

stroke risk factor: Homocysteine & vitamin B deficiencies

Answer 39

- abnormally high homocysteine levels occur with deficiencies of vit B6, B12, & folic acid = high risk of CAD & stroke - homocysteine = major risk factor (second to high BP)

Question 40

stroke risk factor: infections

Answer 40

may play a role in atherosclerosis and heart disease & stroke (inflammatory response) - Lung infections (chlamydia pneumoniae) - Periodontal (gum) disease - Vericella Zoster Virus (chicken pox & shingles)

Question 41

what is a transient ischemic attack?

Answer 41

- a focal loss of neurological function that usually resolves within 24hrs - mini-ischemic stroke, usually caused by tiny emboli that lodge in artery to brain - blood supply quickly restored = no residual damage/symptoms - *warning sign for ischemic stroke*

Question 42

silent brain infarctions

Answer 42

- small strokes that cause no apparent symptoms but are major contributors to mental impairment in elderly (multi-infarct dementia) - up to 31% of elderly people - higher risk in smokers & hypertension

Question 43

what is syncope?

Answer 43

sudden reversible loss of consciousness and postural tone (fainting) that results from temporary global cerebral ischemia

Question 44

what can cause syncope?

Answer 44

- hypotension - decreased cardiac output - blood & metabolic disorders - CNS disorders