EXAM II – STROKE QUESTIONS AND
CORRECT ANSWERS
STROKE-ANSWER Stroke occurs when there is:
1. Ischemia (inadequate blood flow) to a part of the brain
2. Hemorrhage into the brain that results in death of brain cells
Functions such as movement, sensation, or emotions that were controlled by the
affected area of the brain are lost or impaired
Unlike TIA, where ischemia occurs without infarction, a stroke results in infarction
and cell death
The terms BRAIN ATTACK and CEREBROVASCULAR ACCIDENT (CVA) are also
used to describe stroke
Stroke can occur at any age
About 28% occur in those younger than 65
Women are more likely than men to die from a stroke because of the greater number
of women over age 65
Of those who survive a stroke, 50-70% are functionally independent
15-30% live with permanent disability
Common long term disabilities include:
- Hemiparesis
- Inability to walk
- Complete or partial dependence for ADLs
- Aphasia
- Depression
It's a lifelong change for patient AND family
PATHOPHYSIOLOGY OF STROKE - ANATOMY OF CEREBRAL CIRCULATION -
ANSWER-Blood supplies to the brain by two major pairs of arteries
- The internal carotids (anterior circulation)
- Vertebral arteries (posterior circulation)
Carotids branch to supply most of the frontal, parietal, and temporal lobes, the basal
ganglia, and part of the diencephalon (thalamus and hypothalamus)
Major branches of the carotid arteries are:
- The middle cerebral arteries
- The anterior cerebral arteries
The vertebral arteries join to form the basilar artery, which then branches to supply
the middle and lower parts of the temporal lobes, occipital lobes, cerebellum,
brainstem and part of the diencephalon
,Main branch of the basilar artery is the posterior cerebral artery
The anterior and posterior cerebral circulation is connected at the CIRCLE OF
WILLIS by the anterior and posterior communicating arteries
Genetic variations in this area are common, and all connecting vessels may not be
present
PATHOPHYSIOLOGY OF STROKE - REGULATION OF CEREBRAL BLOOD
FLOW - ANSWER-Blood flow must be maintained at 750-1000 mL/min (55/mL/100 g
of brain tissue) - or 20% of the cardiac output
If blood flow to the brain is totally interrupted (e.g., cardiac arrest):
Neurologic metabolism is altered in 30 seconds
Metabolism stops in 2 minutes
Cellular death occurs in 5 minutes
CEREBRAL AUTOREGULATION normally well protects the brain from changes in
mean systemic arterial blood pressure over a range from 50-150 mm Hg
- Autoregulation involves changes in the diameter of cerebral blood vessels in
response to changes in pressure so that the blood flow to the brain stays constant
- When cerebral ischemia occurs, cerebral autoregulation may be impaired
CO2 is a potent cerebral vasodilator
- Changes in arterial carbon dioxide levels have a dramatic effect on cerebral blood
flow
- Increased CO2 increases cerebral blood flow
- Decreased CO2 decreases CBF
Very low arterial oxygen levels (partial pressure of less than 50 mm Hg) or increases
in hydrogen ion concentration also increase cerebral blood flow
Factors that affect blood flow to the brain include:
- Systemic BP
- Cardiac output
- Blood viscosity
During normal activity, oxygen requirements vary considerably, but changes in
cardiac output, vasomotor tone, and distribution of blood flow normally maintain
adequate blood flow to the head
Cardiac output has be reduced by 1/3 before CBF is reduced
Decreased viscosity increases CBF
Collateral circulation may develop over time to compensate for a decrease in
cerebral blood flow
, An area of the brain can potentially receive blood supply from another blood vessel
even if blood supply from the original vessel is cut off (e.g., because of thrombosis)
In other words, the vessels in the brain make an "alternate route" for blood flow to
reach damaged areas
Individual differences in collateral circulation p
RISK FACTORS FOR STROKE - ANSWER-NON-MODIFIABLE RISK FACTORS
- Age
2/3 of strokes occur in people older than 65
Can occur at any age though
- Gender
More common in men
More women DIE from strokes than men (women tend to live longer)
- Ethnicity or race
African Americans > whites
May be related to a higher incidence of hypertension, obesity and diabetes mellitus
in African Americans
- Family history/heredity
Genes encoding products involved in lipid metabolism, thrombosis, and inflammation
are believed to be potential genetic factors for stroke
GENDER DIFFERENCES
- Stroke is more common in men
- Death from stroke occurs more in women (they live longer)
- Men have a better chance of surviving stroke
- Men are more likely to have a thrombotic or embolic stroke
- Women are more likely to have a hemorrhagic stroke
MODIFIABLE RISK FACTORS
- Hypertension
Most important modifiable risk factor
Increases in SBP and DBP independently increase the risk of stroke
Risk can be reduced up to 50% with appropriate treatment of hypertension
- Heart disease
Including atrial fibrillation, myocardial infarction, cardiomyopathy, cardiac valve
abnormalities, and cardiac congenital defects
Atrial fibrillation is responsible for about 20% of all strokes
Risk Increases with age
- Diabetes mellitus
Risk for stroke is five times higher than the general population
- Smoking
Nearly doubles the risk
Risk decreases substantially over time after the smoker quits
After 5-10 years of no tobacco use, former smokers have same risk as nonsmokers
- Excessive alcohol consumption
Risk depends on amount consumed
Women who drink more than one alcoholic drink per day and men who drink more
than two per day are at higher risk for HTN, which increases chance of stroke
CORRECT ANSWERS
STROKE-ANSWER Stroke occurs when there is:
1. Ischemia (inadequate blood flow) to a part of the brain
2. Hemorrhage into the brain that results in death of brain cells
Functions such as movement, sensation, or emotions that were controlled by the
affected area of the brain are lost or impaired
Unlike TIA, where ischemia occurs without infarction, a stroke results in infarction
and cell death
The terms BRAIN ATTACK and CEREBROVASCULAR ACCIDENT (CVA) are also
used to describe stroke
Stroke can occur at any age
About 28% occur in those younger than 65
Women are more likely than men to die from a stroke because of the greater number
of women over age 65
Of those who survive a stroke, 50-70% are functionally independent
15-30% live with permanent disability
Common long term disabilities include:
- Hemiparesis
- Inability to walk
- Complete or partial dependence for ADLs
- Aphasia
- Depression
It's a lifelong change for patient AND family
PATHOPHYSIOLOGY OF STROKE - ANATOMY OF CEREBRAL CIRCULATION -
ANSWER-Blood supplies to the brain by two major pairs of arteries
- The internal carotids (anterior circulation)
- Vertebral arteries (posterior circulation)
Carotids branch to supply most of the frontal, parietal, and temporal lobes, the basal
ganglia, and part of the diencephalon (thalamus and hypothalamus)
Major branches of the carotid arteries are:
- The middle cerebral arteries
- The anterior cerebral arteries
The vertebral arteries join to form the basilar artery, which then branches to supply
the middle and lower parts of the temporal lobes, occipital lobes, cerebellum,
brainstem and part of the diencephalon
,Main branch of the basilar artery is the posterior cerebral artery
The anterior and posterior cerebral circulation is connected at the CIRCLE OF
WILLIS by the anterior and posterior communicating arteries
Genetic variations in this area are common, and all connecting vessels may not be
present
PATHOPHYSIOLOGY OF STROKE - REGULATION OF CEREBRAL BLOOD
FLOW - ANSWER-Blood flow must be maintained at 750-1000 mL/min (55/mL/100 g
of brain tissue) - or 20% of the cardiac output
If blood flow to the brain is totally interrupted (e.g., cardiac arrest):
Neurologic metabolism is altered in 30 seconds
Metabolism stops in 2 minutes
Cellular death occurs in 5 minutes
CEREBRAL AUTOREGULATION normally well protects the brain from changes in
mean systemic arterial blood pressure over a range from 50-150 mm Hg
- Autoregulation involves changes in the diameter of cerebral blood vessels in
response to changes in pressure so that the blood flow to the brain stays constant
- When cerebral ischemia occurs, cerebral autoregulation may be impaired
CO2 is a potent cerebral vasodilator
- Changes in arterial carbon dioxide levels have a dramatic effect on cerebral blood
flow
- Increased CO2 increases cerebral blood flow
- Decreased CO2 decreases CBF
Very low arterial oxygen levels (partial pressure of less than 50 mm Hg) or increases
in hydrogen ion concentration also increase cerebral blood flow
Factors that affect blood flow to the brain include:
- Systemic BP
- Cardiac output
- Blood viscosity
During normal activity, oxygen requirements vary considerably, but changes in
cardiac output, vasomotor tone, and distribution of blood flow normally maintain
adequate blood flow to the head
Cardiac output has be reduced by 1/3 before CBF is reduced
Decreased viscosity increases CBF
Collateral circulation may develop over time to compensate for a decrease in
cerebral blood flow
, An area of the brain can potentially receive blood supply from another blood vessel
even if blood supply from the original vessel is cut off (e.g., because of thrombosis)
In other words, the vessels in the brain make an "alternate route" for blood flow to
reach damaged areas
Individual differences in collateral circulation p
RISK FACTORS FOR STROKE - ANSWER-NON-MODIFIABLE RISK FACTORS
- Age
2/3 of strokes occur in people older than 65
Can occur at any age though
- Gender
More common in men
More women DIE from strokes than men (women tend to live longer)
- Ethnicity or race
African Americans > whites
May be related to a higher incidence of hypertension, obesity and diabetes mellitus
in African Americans
- Family history/heredity
Genes encoding products involved in lipid metabolism, thrombosis, and inflammation
are believed to be potential genetic factors for stroke
GENDER DIFFERENCES
- Stroke is more common in men
- Death from stroke occurs more in women (they live longer)
- Men have a better chance of surviving stroke
- Men are more likely to have a thrombotic or embolic stroke
- Women are more likely to have a hemorrhagic stroke
MODIFIABLE RISK FACTORS
- Hypertension
Most important modifiable risk factor
Increases in SBP and DBP independently increase the risk of stroke
Risk can be reduced up to 50% with appropriate treatment of hypertension
- Heart disease
Including atrial fibrillation, myocardial infarction, cardiomyopathy, cardiac valve
abnormalities, and cardiac congenital defects
Atrial fibrillation is responsible for about 20% of all strokes
Risk Increases with age
- Diabetes mellitus
Risk for stroke is five times higher than the general population
- Smoking
Nearly doubles the risk
Risk decreases substantially over time after the smoker quits
After 5-10 years of no tobacco use, former smokers have same risk as nonsmokers
- Excessive alcohol consumption
Risk depends on amount consumed
Women who drink more than one alcoholic drink per day and men who drink more
than two per day are at higher risk for HTN, which increases chance of stroke
