L6- CVAs Flashcards
list the types of strokes
1) Ischemia: thrombotic or embolic
2) Hemorrhagic: vascular rupture; intracerebral or subarachnoid
both –> (3) Hypoxic: global or focal
all –> infarction
how is imaging used in the diagnosis of stroke
CT (preferred- quicker) or MRI
1) Ischemic Stroke: lesion seen w/in hrs on MRI, appears negative w/in 24hrs on CT
2) Hemorrhagic Stroke: lesion appears immediately after onset
So in ED w/ stroke sxs –> imaging (CT) –> neg will r/o hemorrhagic
list some general causes of functional hypoxia in the brain
- low partial pressure: high altitude
- toxins: cyanide
- dec O2 carrying capacity: anemia
ischemia in the brain occurs in (transient/permanent) fashion due to (2) or (3)
(hypoperfusion)
1- either
2- low BP
3- vascular obstruction
Global Cerebral Ischemia:
- (1) cause
- (2) factors affected outcome
- (3) are the outcomes
1- severe systemic hypotension (MI, shock)
2- severity, duration (rapid, slow), cell type involved
3- widespread neuron death –> severe neurological impairment OR death
describe the susceptibility of different brain cells to ischemia
neurons more than glial cells
-pyramidal cells, Purkinjee cells
______ are the most susceptible brain cells to ischemia (include location)
Pyramidal cells: hippocampus, neocortex
Purkinjee cells: cerebellum
(only mild ischemia is sufficient to cause severe damage)
In (1) ischemia, only the affected area supplied by the vessel is damaged, and (2) is very important in limiting this damage
1- focal cerebral ischemia
2- collateral blood supply
______ area has the greatest risk of a watershed infarction
border zone between ACA and MCA
Watershed infarctions occur more in (global/focal) cerebral ischemia, commonly after (2) events occur. The damage produces a (3) appearance, commonly in (4) location.
1- global
2- hypotensive episodes
3- sickle-shaped band necrosis over cerebral convexity
4- few cms lateral to interhemispheric fissure (for ACA/MCA zone)
what are the types of CVAs due to ischemia, indicate which is more common
- Embolic (more common)
- Thrombolytic
embolic ischemic CVA:
- (1) source
- (2) risk factors (pre-disposing conditions)
1- cardiac mural thrombus, carotid atheromatous plaque
2- AFib, valvular disease, myocardial dysfunction
define paradoxical emboli
venous emboli crosses over to arterial side (bypassing lungs to cause PE) via R –> L shunt (ASD, VSD, patent foramen ovale) leading to ischemia (legs or stroke)
thrombotic occlusion ischemic CVA:
- (1) definition
- (2) list the possible progressions
1- thrombus superimposed on atherosclerotic plaque
2:
- can have anterograde extension
- can fragment / embolize
- can lead to Small Lacunar infarcts
define small lacunar infarcts
- via thrombotic occlusion ischemic CVA
- -> occlusion of penetrating arteries via HTN
describe the gross morphology of ischemia of the brain
- swollen brain: wide gyri, narrowed sulci
- poor demarcation between white/gray matter
- liquefied tissue => fluid filled cavity