ICL 10.6: Stroke Flashcards
what is a stroke?
a sudden onset of neurological deficit caused by alteration in blood flow to a portion of the brain
what is a TIA?
transient (<24 hours) focal symptoms and neurological deficits secondary to ischemia
most resolve in within 60 minutes – if it doesn’t, it usually transitions into a stroke
what are the 2 subtypes of strokes?
- primary ischemic (80%)
- primary hemorrhagic (20%)
less common but has a higher mortality rate
what are the 2 types of hemorrhagic stroke?
- subarachnoid hemorrhage
2. intracerebral hemorrhage (in the parynchamal tissue)
what usually causes a subarachnoid hemorrhage?
- Berry aneurysm rupture
- fusiform aneurysms can also cause SAH but those are usually from hypertension
- mycotic aneurisms are usually from an infectious source
25% mortality, usually effects women more than men, over 50 years old
usually solitary so it’s just one aneurism
what is the location of most aneurysms?
- anterior communicating artery
- posterior communicating artery
- middle cerebral artery
how can you treat an aneurism?
- surgically by opening up the skull and clipping off the aneurism
- interventional by going in with a catheter and filling the aneurism with coils
what are the causes of intracerebral hemorrhage?
- hypertension**
- cerebral amyloidosis
- arteriovenous malformation (AVM)
- medications
- illicit drugs
hypertension related intracerebral hemorrhages are usually located in what parts of the brain?
- putamen-claustrum
- cerebral white matter
- thalamus
- pons
- cerebellum
what is the big problem with intracerebral hemorrhages in the posterior fossa?
they’re not very forgiving, the fossa doesn’t have that much space and it’s really contained so whenever you have a bleed or stroke causing ICP, you have high risk of herniation
what are the types of ischemic stroke?
- embolic/thrombotic
- large vessels disease
- small vessel disease
- other
- unknown
what is an embolic stroke?
blockage of a blood vessel by material that originated elsewhere
can be cause by atrial fibrillation, air, amniotic fluid, fat paradoxical, or aortic atheroma = plaque in the aorta
which artery is most frequently effected by embolic stroke?
middle cerebral artery
what is a paradoxical emboli?
patent foramen oval is an opening between the left and right atrium
if someone has a DVT in the leg or arm, it can break loose and travel to the right atrium then pass over through the PFO to the left atrium and then go up and cause a stroke in the brain via the aorta, carotid artery, vertebral artery etc.
most people with DVTs end up with a PE but it’s a possibility that the DVT could cause a stroke
what is a large vessel occlusion strokes?
a type of ischemic stroke that is caused by occlusion of large vessels
the symptoms are often fluctuating because even though the large vessel is occluded, you have collateral flow that is trying to compensate for this
75% are in the anterior circulation because of the carotid while only 25% are in the posterior like the vertebral artery
what are the common causes of large vessel occlusion strokes?
- atherothrombotic at primary intracranial artery site
- atherosclerotic embolism to intracranial artery
- cardioembolic – like if you form a clot in the heart from afib and then it goes to the MCA
- dissection – usually in trauma where the torn artery wall leads to a blood clot that compresses the lumen of the artery or the clot can throw distal emboli both causing a stroke (slide 31)
- cryptogenic aka stroke of unknown cause
what is a small vessel occlusion stroke?
a type of ischemic stroke that is caused by occlusion of small vessels that be look like lacunar infarct on CT
usually happens in the small vessels of the subcortical white matter, deep gray structures or brainstem
variable presentation: patients will present with pure motor, pure sensory or dysarthria/clumsy hand on one side of the body
how can you differentiate between a small vs. large vessel occlusion stroke?
on a CT, a small vessel stroke will look like a lacunar lesion while a large vessel stroke will usually be the whole territory of a vessel like the MCA (slide 34)
also patients will present differently: SVO doesn’t have cortical involvement so there won’t be cortical signs – the cortex controls all your higher functioning like speech, vision, sensory motor and in an SVO these will all be preserved!
what are the 3 major arteries that the aorta gives off?
when you’re looking for thrombi in an angiogram, always start at the aorta and check the blood vessels it gives off
- R brachiocephalic –> R subclavian –> R common carotid
- L common carotid artery
- L subclavian artery –> vertebral artery branches off
slide 38
what is the concept of core vs. penumbral region in a stroke?
core region is irreversibly injured tissue
penumbral region is the reversibly injured tissue - it may recover or it may evolve into infarction or it may die by apoptosis
what are the areas/cells of the brain that will first suffer from hypoxia?
- hipocampus
- 3rd, 5th and 6th layer of the cortex
- purkinje cells of the cerebellum
- watershed areas
- brainstem nuclei in infants
what is the pathogenesis of a stroke? aka how does it develop?
- reduced blood supply causes hypoxia/anoxia
- altered metabolism means the Na/K pumps are blocked
- glutamate receptors are activated and you get a calcium influx
1-6 minutes is ischemic injury with red neurons and vacuolation
more than 6 minutes without oxygen causes cell death and karyorrhexis = the destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm
what are the infarct stages?
- immediate: <24 hours
no gross changes, micro Na/K loss, Ca+ influx
- acute stage: < 1 week
edema, loss of grey/white matter border, inflammation, red neurons, necrosis, neutrophils
- intermediate stage (subacute): 1- 4 weeks
stroke is clearly demarcation, soft friable tissue, cysts, macrophages, liquifactive necrosis from macrophages
- late stage (chronic) : > 4 weeks
removal of tissue by macrophages, fluid filled cysts with dark grey margin (gliosis)
gliosis = proliferation of glia at periphery
what is the general clinical presentation of a stroke?
- loss of strength and/or sensation, particularly on one side
- sudden dizziness, imbalance
- loss of vision—visual field, or one eye
- difficulty speaking or understanding
- sudden severe headache
