Transcript Chapter 6 Cerebrovascular Disease and Stroke

Chapter 6
Cerebrovascular Disease and Stroke
• Stroke: Loss or impairment of body function resulting from injury or death
of brain cells following insufficient blood supply.
• TIA (transient ischemic attack): Is not a stroke but it can be prodromal
(early) symptom. Precedes about 15% of strokes and are a major risk
factors—especially for older people.
• Five Common Signs of Stroke: (1) Sudden numbness or weakness of the
face, arm, leg, especially on one side of the body (2) Sudden confusion and
trouble speaking or understanding (3) Sudden trouble seeing in one or both
eyes (4) Sudden trouble walking, dizziness, or loss of balance or
coordination (5) Sudden, severe headache with no known cause
• About 85% of strokes are classified as primary ischemic or thrombosis
(clotting in a vessel) usually from atherosclerosis or from embolism
(occlusion of a vessel by a circulating atheroma or clot, often from the
heart). Another10% result from bleeding n the brain—primary intracerebral
hemorrhagic strokes.
Magnitude of the Problem
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P-125
Cerebrovascular disease (CVD) killed about 4.4 million worldwide in 1990,
second only to CHD. A decade later it killed 5.4 million.
Blacks in the US have almost twice the risk of first ever stroke compared with
whites. Age-adjusted rates per 1000 people aged 45 to 84 years are 6.6 in black
males, 3.6 in white males, 4.9 in black females, and 2.3 in white females.
About1/3 of people who have had 1 or more TIA’s have a stroke within 5 years.
Among people ages 45 to 64, 8% to 12% of ischemic strokes and 37% to 38%
of hemorrhagic strokes result in death within 30 days.
In addition to mortality, stroke is also the leading cause of adult disability in the
US. (body functions, gait problems, impaired vision, speech, comprehension,
depression, memory loss and paralysis).
Stroke has been the 3rd leading cause of death in the US since 1938.
Risk Factors for Stroke
• Age: Stroke risk doubles each decade after age 55. Two-thirds of stroke
occur in people older than 65.
• Sex: Women have slightly higher stroke risk and are more likely to die
from stroke than a man but men die sooner than women from other causes
so there are more female than male stroke survivors in the US.
• Race: Blacks have 2 x the risk of stroke of other Americans maybe because
they have more of the other key risk factors.
• Atrial fib: irregular contraction of the hearts atria causes an irregular HB
which can lead to pooling of blood in the heart and contribute to clot
formation and ischemic stroke.
• CHD: Atherosclerosis inderlies both CAD and carotid artery disease and is
thus a main cause of ischemic stroke—hence, people with CHD are at
increased risk of stroke.
• Obesity, hypercholesterolemia, and physical inactivity are secondary
contributing risk factors to stroke.
• Modifiable Risk Factors: Hypertension, Smoking, Alcohol Abuse,
Hypercholesterolemia, diabetes and obesity.
• Hypertension:
• Smoking: Damages arteries and furthers atherosclerosis.
• Alcohol Abuse: ETOH has been shown to increase and decrease the risk
for stroke.
• Hypercholesterolemia: Associated with only a moderate increase in risk for
stroke—Statin drugs though, may reduce thickening of the carotid artery
wall and thus reduce the frequency of strokes by about 30%.
• Obesity & Diabetes: Overweight (BMI) is an independent risk factor for
stroke and in young adults stroke is nearly 12 X higher in those with
diabetes—possibly explained by microvascular disease.
Etiology of Stroke
• Pathophysiology invloves atherosclerotic disease and hemostatic
dysfunction similar to CHD.
• Embolic stroke: (ischemic stroke) Caused by blockage of one of the arteries
to the brain by a blood clot that has usually formed somewhere else like the
heart, broken free and moved to the brain as an embolus.
• Lacunar: Reduced Perfusion: Brain cavities resulting from decreased
perfusion in small, deep vessels. Occur with severe stenosis (greater than
70% narrowing) of the carotid and basilar arteries and with stenosis of
small arteries deep in the brain.
• Thrombotic Stroke: P-129
Physical Activity and Stroke Risk: The Evidence
• Physically active men and women generally have a lower risk of stroke
incidence or mortality than do the least active—with more active persons
demonstrating a 25% to 30% lower risk for all strokes.
• Studies: P-130-135.
• Peripheral Artery Disease (PAD): Is the obstruction of blood flow in
arteries other than those to the heart or brain, usually because of
atherosclerosis.
• There is evidence that PAD is a stroke risk factor.
• Strength of Evidence: P-136.