Transport and Cerebral Perfusion (Week 5) Flashcards
Causes of a stroke
Ischemia in a brain area; 80% of strokes
Hemmorhage of a brain blood vessel; 20%
Stroked can result in loss or impaired:
Movement, sensation or emotions.
Hemiparesis
1- sided weakness (partial parylysis)
After effects of a stroke
- Hemiparesis
- Inability to walk
- Partial or complete loss of independence in performing 4.ADL’s
- Aphasia
- Depression
Unmodifiable risk factors of stroke
- Age
- Sex
- Race
- Genetics
Modifiable risk factors of a stroke
- Hypertension
- Heart disease
- Diabetes
- Hypercholesterolemia
- Smoking
- Alcohol <2good, >2bad
- Obesity
- Physical inactivity
- Poor Diet
- Cocaine
- Birthcontrol
- Migrane headaches
- Hypercoaguability
- Chronic Inflammation
- Hyperhomocystenimia
- Sickle cell anemia
Primary blood vessels that supply the brain with blood
Carotid Arteries
Vertebral arteries
Where does the greatest risk of stroke development occur?
Circle of Willis
How much blood supply does the brain require
20% of the bodys cardiac output, 750-1000 mL/min.
How fast do CNS changes occur after complete loss of bloodflow to the brain?
30 sec Permanent damage (cell necrosis) within 5 mins
What are the factors that contribute to the severity of stroke damage?
- Rate of onset
- Size of lesion
- Presence of collateral circulation
Cerebral Autoregulation
Refers to the ability of the brains bloodvessels to adapt to systemic blood pressure changes. Adjusts mean systemic blood pressures of 50-100 mmHg.
How does increased CO2 levels effect brain blood supply?
Increases blood flow (it is a potent vasodilator)
How does atherosclerosis contribute to a stroke?
- Plaque depositions narrow the blood vessels creating areas for the clots to become lodged.
- Bits of plaque break off and become lodged in smaller vessels.
- Weakening of blood vessels from atherosclerosis increase risk of hemorrhage.
3 Types of Ischemic strokes
- Thrombotic
- Embolic
- Lacunar
Thrombotic Stroke
Occur when a clot or plaques form and occlude vascular blood flow.
Embolic strokes
Occur when a circulating clot or piece of broken off plaque becomes lodged in a narrow vessel. Most clots originate in the heart (endocardial) from AFib or Valvular disease.
Lacunar Strokes
When a vessel supplying blood to the deeper structures of the brain becomes blocked. Can be asymptomatic b/c of collateral circulation.
When symptoms do occur they are severe including hemiplegia, or total collateral sensory loss.
What kind of stroke has much more sudden effects and severe symptoms.
Embolic
Cerebral Infarction
Death of brain cells from cerebral ischemia.
Classifications of Hemorrhagic strokes
Intracerebral, intraparenchymal, subarachnoid, or intraventricular.
Transient ischemic attack (TIA)
Essentially a “temporary stroke”. When an area become ischemic but blood flow is restored after a period of time.
Intracerebral hemorrhages
Bleeding in the brain caused by a ruptured blood vessel. HTN is the greatest cause. 50% death rate.
Subarachnoid Hemorrhage
When there is bleeding into the CSF space between the pia matter and the arachnoid membranes covering the brain. Usually occurs due to the rupture of a cerebral aneurysm.
Clinical Manifestations of stroke
- Changes in motor function.
- Changes in intellectual function.
- Spatial-perceptual alterations.
- Communication changes.
- Changes in affect.
- Changes in elimination function.
Motor function symptoms of stroke
Motor deficits are the most apparent symptoms of a stroke and are seen as a loss of function in mobility, rep function, swallowing and speech, gag reflex, and ability to perform ADL’s.
Akenesia
Loss of skilled voluntary movement.
A stroke on which side of the brain causes aphasia?
Left
Expressive aphasia is known as what?
Broca’s aphasia
Receptive aphasia is known as what?
Wernike’s aphasia
Amnesic Aphasia
“loss of words”
Global Aphasia
Loss of receptive and expressive function.
Dysarthria
Disturbances in the muscular components of speech.
Intellectual function
Changes in memory and judgement from stroke. Left sided stroke pt’s become more cautious. Right- more impulsive
Perceptual alterations
Four primary types:
- Anosognosia - Inability to recognize objects
- Erroneous perception of self in space - Sensory input from one side of body.
- Homonymous hemianopsia- is when blindness occurs on one half of the visual field of both eyes)
- Apraxia- The inability to carry out learned sequences of movement.
Affect post stroke
After a stroke the individual may express exaggerated or uncontrollable emotions of any type. Often depression will become evident.
Elimination function post stroke
Because of loss of sensory and muscle function, constipation and urinary retention commonly occur. These are most often resolved after time.
Diagnostic studies re: stroke
MRI/CT, they can determine it was in-fact a stroke as well as determine the cause of the stroke.
Stroke prevention (collaborative care)
- Blood pressure control
- Blood glucose control
- Diet and exercise
- Smoking cessation
- Limiting alcohol consumption
- Routine health assessments
Drug therapy for strokes
Hypertensives, aspirin ( or other antiplatelets like clopiodril). Patients with Afib are also prescribed prophylaxis such as warfarin.
Carotid Endarterectomy
Surgical removal of artheromatous areas from the carotid artery.