Stroke Flashcards
Stroke: when does it occur?
- when there is ischemia (inadequate blood flow) to a part of the brain that results in the death of brain cells
How much blood does the brain need?
Cerebral blood flow must be maintained at 20% of cardiac output
What happens if blood flow to the brain is totally interrupted?
- neurological metabolism altered in 30 seconds
- metabolism stops in 2 minutes
- cellular death occurs in 5 minutes
Cerebral autoregulation
- changes in diameter of cerebral blood vessels in response to changes in pressure so the pressure in the brain stays constant
- may be impaired following cerebral ischemia
what factors affect blood flow to the brain?
- systemic blood pressure - when BP drops, vessels dilate and individuals faint because the BP dropped and the brain isnt getting adequate blood flow
- cardiac output - is there damage to the heart or has there been? history of CAD, MI, is the heart pumping adequately
- Blood viscosity
- Arrangement of the brain’s arteries
Collateral Circulation
- another way the body manages risk factors
- if main vessel is clogged, there are numerous ways for blood to get to the area of the brain
- cardiac output has to be reduced by 1/3 before there is reduced blood flow to the brain
- outcome of stroke depends on amount of collateral circulation
Non-modifiable risk factors
Age>65
gender - males have more strokes. females die from them more
race - african american
family history - immediate family member had a stroke
Modifiable Risk Factors
- smoking
- obesity
- alcohol
- inactivity
- high cholesterol
- illicit drug use
- oral contraceptives
Contributing Factors
Hypertension
diabetes (4-5x more likely)
heart disease/CAD (anything related to hearts ability to pump)
Atrial Fibrillation
- most important treatable cardiac related risk factor for developing stoke because the blood is not moving effectively, clots are forming in the quivering atria are then pumped into the brain and can cause stroke
Thrombosis
a clot that forms and stays put and blocks off a vessel. starts in one spot and stays in one spot
Embolism
clot that develops somewhere else, travels, and gets stuck. Can travel from the heart, up from somewhere in the body
Hemorrhage
breaking in vessel wall. rupture of atherosclerotic vessels. produces extensive residual functional loss. Most commonly caused by hypertension .
Types of Strokes
- Ischemic Stroke (85% of strokes) TIA Thrombotic - plaque Embolic - Hemorrhagic Stroke - bursting. ischemic effects when there id bleeding into the brain and the tissues that need it are not getting it. increased ICP Intracerebral Subarachnoid
Progression of ischemic stroke
Thrombosis/embolism -> cerebral infarction (loss of blood supply) -> decreased cerebral percusion and increased ICP -> cerebral ischemia (cell death)
Progression of hemorrhagic stroke
hypertension/aneurysm -> cerebral hemorrhage -> decreased cerebral perfusion and increased ICP -> cerebral ischemia
TIA (transient ischemic attack)
- precursor to ischemic stroke - temporary loss of neuro function lasting < 24 hours. often < 15 minutes.
- caused by microemboli
- patients should go to emerge
Who is at risk for TIA?
- everybody who is at risk for ischemic stroke
- people at risk of a clot forming and traveling
Thrombotic Stroke
- 61% of strokes
- occurs when artery providing blood to brain tissue is blocked - intracranial thrombus
- symptoms slow and progressive, may not have changes in LOC in 1st 24 hours
Lacunar stroke
very deep in a very small vessel
- dementia
Embolic (24% of strokes)
- traveling embolus (often from heart)
- symptoms sudden, no chance of developing collateral circulaiton
- prognosis dependson amount and location of brain tissue affected
Who is at risk for an ischemic stroke?
- hypertension
- known cardiovascular disease
- A-fib
- smoking
- drug use
- inactivity
- diabetes
- ask assessment questions
Hemorrhagic Stroke (15%) Intracerebral (10%)
- hypertension is a significant risk factor
- occurs during activity
- sudden onset with progression of symptoms of min-hours because of bleeding
- headache, nausea, vomiting, sudden alteration in LOC, hypertension
- poor prognosis
Subarachnoid hemorrhagic stroke
- intracranial bleeding into CSF space
- often rupture of cerebral aneurysm can also be trauma or cocaine
- headache, nausea and vomiting, sudden alteration in LOC, hypertension
- poor prognosis
Clinical Manifestations: motor function
- impairment of speech, voluntary movement, swallowing, numbness, paralysis, lack of sensation
- Akinesia - trouble with voluntary movement
Clinical Manifestations: Communication
- left hemisphere dominant: language disorders, comprehension of written and spoken words. Depends on where in the brain the stroke is affecting. Slurred speech, or not making sense, stringing words together that do not make sense.
Broca’s aphasia
difficulty expressing thoughts or words
Wernickes aphasia
difficulty understanding spoken or written language
Amnesic aphasia
problems finding correct names for objects or things