Stroke Flashcards
Name several top risk factors for stroke.
- A Fib
- Unregulated hypertension
- TIA
- Heart disease
- Diabetes
How is a transient ischemic attack different than stroke?
It lasts less than 24 hours and resolves completely.
-Caused by embolus from heart or other large vessel
What are the two types of stroke, and which is more prevalent?
ISCHEMIC (88%)
HEMORRHAGIC (12%)
Ateriosclerotic is a large vessel stroke. What are embolic and lacunar?
Medium and small vessels respectively.
What factors worsen ischemic stroke?
- Rate: fast onset and long duration
- Inadequate systemic BP for perfusion
- Hypercoagulation
- Hyperthermia
- Hyperglycemia
- Collateral circ
Normal CBF = 50ml/100gm/min. WHen it falls below 20ml, what happens?
- Electrical silence to preserve energy
- Penumbra (CBF = 25-50% normal)
- period where impairment due to ischemia is partially or fully reversible
During stroke, noxious metabolites are released after neuron breakdown and injury of adjacent neurons. What happens after?
Leaky BBB
- causes brain edema 48-72 hours after onset
- leads to larger infarcts, further damage
Why do neurons dump glutamate which leads to metabolite excitotoxicity?
In response to ischemia. Calcium then floods the cells which results in membrane damage.
One hour after onset apoptosis occurs. What is its trigger?
Influx of calcium.
How does conversion to hemorrhagic stroke occur?
Damaged brain blood vessels from ischemia rupture after blood flow is restored, called a “red infarct”.
- less collateral circ
- large infarct
What is the most common site of large vessel disease? What % of blockage is required for it to be significant?
Bifurcation of vessels.
70%
Describe the pathogenesis of large vessel disease.
- Damage to vessel wall
- platelet congregation
- thrombogenesis
- plaque formation
- blockage
What is the most common pathology of medium sized vessel disease?
Embolism, mostly affects cerebral arteries from heart-made embolis
-a fib is culprit for embolus formatoin
T/F embolus formation is common at bifurcation points of vessels.
True.
What is the most common pathology with small vessel disease?
Lacunar
- changes in the intima
- lipofusion deposits
- hypertension, diabetes
What area of the brain is most commonly affected by small vessel disease?
Deep white matter
- inc internal capsule
- isolated deficits
Microvessel disease is common with dimentia and PD. What type of deposits in arterioles and capillaries cause it?
Amyloid deposits.
tPA is a good treatment for acute stroke. What is its effective window?
3 hours by IV
6 hours locally & intra-arterially
Name two types of hemorrhagic aneurysms.
Berry
- congentital weakness
- mostly in ant half of circ Willis
Charcot Bouchard
- burst aneurysm found on penetrating vessels in brain
- prognosis good if hemorrhage resorbed
What type of hemorrhage is the result of a berry aneurysm?
Subarachnoid
What are common causes of TIA?
Embolism
Stenosis-related hypoperfusion
What arteries come off the internal carotid for anterior circulation?
MCA, ACA, posterior communicating
What arteries are included in the vertebral basilar system?
PICA, basilar, PCA
What is the penumbra?
Area surrounding the core of infarction
- Some preservation of energy metabolism
- 25 to 50% CBF of normal
Reversible in 3 hours
What is a “red infarct” and its associated factors?
When occluding embolus lyses and migrates distally, resulting in hemorrhage.
- size
- richness of collateral circ
- use of anticoagulents
With hypoperfusion (watershed / borderzone) stroke, what are common sequellae?
- Pump failure from MI
2. Distal territory of cerebral artery affected
Why is a berry aneurysm the worst headache of your life?
The blood pushes on the arachnoid space which is innervated, causing severe pain.
T/F: Brain tissue is not damaged by contact with blood.
False, iron is damaging.
What is an intraparenchymal hemorrhage?
Bleed into substance of brain, direct contact
T/F: A dissecting aneurysm is from trauma to the vessel?
True.
