ICL 10.5: Cerebrovascular Pathology Flashcards
what are the 3 basic categories of stroke?
- thrombosis
- embolism
- hemorrhage
strokes are the MOST PREVALENT of the neurological disorders
what are the 2 processes that occur during a stroke?
- hypoxia, ischemia and infarcation
2. hemorrhage
what is a TIA?
TIA = transient ischemic attack
it’s a temporary deficit due to temporarily decreased perfusion –> lasts less than 24 hours
no permanent damage
high risk of stroke
what are the top 3 causes of stroke?
- brain infarction (thrombotic or embolic) –> 80%
- intracerebral hemorrhage (usually due to hypertension) –> 10%
- subarachnoid hemorrhage (usually due to ruptured Berry aneurism) –> 7%
what are the nutritional requirements of the brain?
it needs a constant supply of oxygen and glucose
so the blood flow to your brain is constant no matter the changes in BP or ICP –> the brain autoregulates itself!
what is hypoxia?
decreased amount of oxygen
what is anoxia?
no oxygen
what is ischemia?
a decrease in blood flow
the odds of a patient surviving a stroke are dependent on what factors?
- collateral circulation presence
- duration of ischemia
- magnitude and rapidity of ↓ decrease of blood flow
what is a focal infarction?
when there is a cerebral blood vessel occlusion involving all or part of an arterial territory
it’s due to a focal interruption of blood supply of that artery by thrombosis, embolism, compression, trauma, etc.
the outcome is focal deficits which is a classic stroke!
what are the 3 cerebral arteries and what are their territories?
- posterior cerebral artery
- middle cerebral artery
- anterior cerebral artery
slide 9 go look at which territories they’re responsible for!!!
what is global ischemia?
a generalized reduction in cerebral blood flow usually due to either cardiac arrest, shock or severe hypotension –> essentially you’re cutting off blood to the entire brain
when it’s severe it’s known as diffuse ischemic/hypoxic encephalopathy and can cause widespread neuronal death
what are the possible outcomes following a global ischemia?
- mild = perhaps normal (TIA)
- intermediate = varying degrees of cognitive impairment up to persistent vegetative state
- severe = brain death
what are watershed infarcts?
the areas between the cerebral arterial territories –> they’re border zones between arterial territories
they’re the most vulnerable to global ischemia because they’re the farthest away from a blood supply and tend to be the most effected during a global ischemia event
which cells are the most sensitive to global ischemia and are effected first when it occurs?
- CA 1 territory - hippocampus
- purkinje fibers - cerebellum
- cortical pyramidal neurons
how can you tell a neuron is dead histologically?
neurons are usually lavender but when they’re dead they look pinky red!
slide 12
what causes a thrombosis (that could later lead to a stroke)?*
atherosclerosis
there are atherosclerotic plaques usually in the carotid artery and then something happens where a piece of it breaks off which exposes the sticky stuff underneath and then you get plaque ulceration where more platelets and RBCs stick to it which extends the thrombus and makes it bigger!
what is the most common site for a thrombosis? what will happen if there’s a thrombosis at this site?*
the carotid artery bifurcation
it leads to an infarction of the MCA territory
what are the 2 most common origins of embolisms?
- heart (most common source)
can be thrombotic emboli from the ventricles of heart disease patients or septic emboli in people who have vegetations on their valves like mitral valve endocarditis
- arteries (specifically the carotid)
atheromatous plaques can break off and send emboli to the brain or you can get thromboembolism overlying the atheroma
note: other sources of emboli are from tumors, fat, amniotic fluid or air
what are the 2 types of infarcts?
- hemorrhagic (red) infarcts
2. non-hemorrhagic (pale) infarcts
what are hemorrhagic infarcts?
multiple, often confluent, petechial hemorrhages
associated with embolic events
hemorrhage due to reperfusion injury –> so when the emboli dislodges and flow is restored, it causes repercussion injury
no thrombolytic therapy
slide 16
what is a non-hemorrhagic infarct?
associated with thrombosis
patients are potentially eligible for thrombolytics
hypertensive cerebrovascular disease most often effects what part of the brain?
basal ganglia
what are the most important gross effects of hypertensive cerebrovascular disease?
- lacunar infarcts
- slit hemorrhages
- hypertensive encephalopathy
what are lacunar infarcts?
arteriolar sclerosis (HTN) of deep penetrating arteries cause lacunae = small cavitary infarcts from the dead brain tissue that has left holes
most commonly effect basal ganglia, white matter, brain stem
can lead to vascular (multi-infarct) dementia because they can happen more than once without detection and eventually it causes dementia
what is a slit hemorrhage?
rupture of small penetrating vessels which leads to small hemorrhages that cause slit-like cavities
it’s necrosis of the brain and the brain doesn’t fix it so it’s a slit looking defect
what is hypertensive encephalopathy?
there’s increased ICP and fibrinoid necrosis of the arterioles which causes diffuse cerebral dysfunction
patients will present with headache, confusion, vomiting, convulsions, coma, herniation and even death
this is a medical emergency!!
what can cause an intracerebral hemorrhage?
- hypertension
- berry aneurysm that causes a massive subarachnoid hemorrhage
- vascular malformations like arteriovenous malformations (most likely to bleed), venous malformations or cavernous (hem)angiomas
what is a Berry aneurysm?
a pouch-like protrusion due to weakening of an arteriole wall
90% are found at major arterial branch points in anterior circulation like the anterior cerebral artery and anterior communicating artery branch point
they can rupture if they’re larger than 10 mm or there’s acute increased ICP
there’s a 50% mortality with the 1st rupture because they cause a massive subarachnoid hemorrhage so they’re really serious
what is an arteriovenous malformation?
a shunt of blood directly from an artery to a vein
looks like a crazy tangle of vessels where the veins have dilated in response to exposure to arterial pressures – there’s also abnormal vessels separated by gliotic tissue
the veins are not used to dealing with the same type of blood pressure that an artery does so they are at risk for rupture and can bleed suddenly and massively
these are the most dangerous type of vascular malformation!
slide 26
what are the types of venous malformations?
- cavernous hemangioma
- venous hemangioma
usually pretty benign but if they get big enough they can cause a problem
looks like hyalinized veins of various sizes but with NO intervening neural parenchyma
slide 27
