Strokes Flashcards

1
Q

ischemia

A

inadequate blood supply (including O2 and glucose)

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2
Q

prolonged ischemia results in ____

A

infarction (cell death)

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3
Q

anoxia

A

inadequate oxygen supply

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4
Q

what can cause a stroke?

A
  • ischemia: result of occlusion (blocked a due to atherosclerosis or blood clot)
  • hemmorrhage (bleeding a due to ruptured aneurism or hypertension)
  • hypotension
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5
Q

what is the cause of the majority of strokes?

A

ischemia (caused by clotting)

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6
Q

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

A
  • thrombotic (eg. lacunar)
  • embolic
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7
Q

when does a thrombotic stroke usually occur?

A

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)

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8
Q

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

A

macrophages
neutrophils

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9
Q

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

A

cytokines
attract more white blood cells and perpetuate the cycle

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10
Q

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

A
  • nitric oxide (maintains BV elasticity)
  • arteries become calcified & lose elasticity
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11
Q

how does a thrombus form?

A
  • atherosclerosis -> macrophages & neutrophils
  • immune system -> cytokines
  • injured walls -> insufficient NO -> calcified aa
  • arterial walls stenose -> occlusion of blood flow
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12
Q

in atherosclerosis, arterial walls…

A

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

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13
Q

Lacunar stroke

A

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

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14
Q

a lacunar stroke may cause…

A

clumsiness
weakness
emotional variability
(depending on branch affected)

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15
Q

an embolic stroke is usually caused by an ____

A

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

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16
Q

what are 4 possible causes of an embolus?

A
  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)
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17
Q

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

A

blood-brain barrier

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18
Q

what is the blood-brain barrier?

A

a wall of tiny vessels and astrocytic feet

19
Q

what occurs in a hemorrhagic stroke?

A
  • arteries weaken & break open
  • blood-brain barrier is broken
  • accompanied by a catastrophic headache
20
Q

name 2 location-based categories of hemorrhagic strokes

A
  • intracerebral or parenchymal (bleeding within cerebrum)
  • subarachnoid (bleeding into subarachnoid space)
21
Q

what causes hemorrhagic strokes?

A

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

22
Q

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

A
  • balloon-like dilations of arteries
  • dome of dilation is fragile and may rupture and cause bleeding
23
Q

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

A
  • abnormal connection between arteries & veins
  • if it occurs in the brain & ruptures, may cause hemorrhagic stroke
24
Q

hypertensive hemorrhages tend to be ____

A

intracerebral

25
Q

what is hypotension and how does it cause a stroke?

A
  • 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
26
Q

name the risk factors for stroke

A
  • 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
27
Q

stroke risk factor:
Age

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

stroke risk factor:
Gender

A

mortality higher in women

29
Q

stroke risk factor:
Ethnicity

A

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

30
Q

stroke risk factor:
Geography

A
  • highest risk in Southeastern US
  • also high in lower Mississippi valley & Southern California
31
Q

stroke risk factor:
Hypertension

A
  • contributes to 70% of all strokes
  • wider spread between systolic & diastolic = greater risk
32
Q

stroke risk factor:
Atrial Fibrillation

A

1 in 6 strokes due to A-fib

33
Q

stroke risk factor:
Smoking

A
  • pack a day = 2.5x greater risk as non-smokers
  • increases both hemorrhagic & ischemic stroke risk
34
Q

stroke risk factor:
Obesity & sedentary lifestyles

A

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

35
Q

stroke risk factor:
Cholesterol & other lipids

A
  • HDL important for preventing strokes
  • hypertensive pts with overall cholesterol levels <180mg/dl = risk for hemorrhagic stroke
36
Q

stroke risk factor:
Alcohol, Coffee, & Drug abuse

A
  • 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)
37
Q

stroke risk factor:
Mental & emotional factors

A
  • Stress: men w/ intense response to stress, chronic or frequent stress (higher BP) = higher risk
  • Depression: higher risk of stroke and lower survival rates
38
Q

stroke risk factor:
migraines

A
  • 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
39
Q

stroke risk factor:
Homocysteine & vitamin B deficiencies

A
  • 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)
40
Q

stroke risk factor:
infections

A

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)

41
Q

what is a transient ischemic attack?

A
  • 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
42
Q

silent brain infarctions

A
  • 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
43
Q

what is syncope?

A

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

44
Q

what can cause syncope?

A
  • hypotension
  • decreased cardiac output
  • blood & metabolic disorders
  • CNS disorders