Brain Circulation and Stroke Flashcards
how common is stroke?
every 10 minutes someone in canada suffers a brain attack aka stroke
what is the number one cause of disability and number three cause of death?
stroke
what does ‘stroke; mean?
apoplexy = struck down with violence .. this is the word that stroke stemmed from… stroke first used in 1599 to describe the apoplectic seizure
What is a stroke defined by world health organization?
world health organization define it as a neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours
What are two types of strokes described by Wepfer?
- ischemic stroke –> isn’t really visible, its when theres low blood to certain area of the brain due to occlusion in the artery … the cortical ribbon surrounding the right hemisphere is pale and white
- hemorrhagic stroke –> this is visible in post mortum brain because its a visible huge blood clot in the brain due to blood leaking
what is an acute ischemic stroke? what percentage of strokes comprises of this?
ischemia in general is lack of blood flow
acute ischemic stroke is caused by occlusion of a blood vessel usually via thrombosis (blood clot) in that artery or a thrombo-emobolism which is a blood clot somewhere else in the body that moves upwards towards the brain
this accounts for 80% of stroke
What is spontaneous intracranial hemorrhage?
when microscopic vessels rupture and cause macroscopic bleeding (bruising but with bleeding)
what are two types of spontaneous intracranial hemorrhage?
- aneurysmal subarchanoid hemorrhage (5-10% of strokes) –> rupture of blood vessel and bleeding outside of the brain
- intracerebral hemorrhage (10-15% of stroke) [second common cause of stroke]
How do we visual stroke?
using CT scans or angiograms that take slices of the brain
What are symptoms of stroke?
when subarchanoid hemorrhage touches your meninges, it gives you the worst headache of your life
signs:
- unilateral weakness on one side or numbness
- trouble speaking and understanding
- loss or change in vision
- sudden onset of dizziness and loss of balance
- sudden onset of first and worst headache
what is aphasia/dysphasia? which hemisphere does it occur and what are two types?
its when people have trouble understanding or producing speech
brook’s aphasia is also called non-fluent aphasia which is characterized by slow, halting, effortful speech, frustrated, relatively good comprehension
wernicke’s aphasia is characterized as empty, speech, word salad and poor comprehension
dysarthria is slurring of words
this usually occurs in the left hemispheres
what is neglect/ heme-inattention?
right parietal lobe lesion that causes person to not see their left side
what is hemiplegia?
stroke that affects the internal capsule of white matter
symptoms include contralateral weakness
what are the two main arterial supply to the brain?
vertebral artery and internal carotid artery
they join up at the circle of willis in the brain and are connected by basilar artery
which arteries innervate the anterior circulation?
The internal carotid artery supplies the anterior circulation and its composed of anterior cerebral artery and middle cerebral artery
which arteries innervate the posterior circulation?
posterior cerebral artery and basilar artery
why do we have the circle of willis?
for evolutionary protection so if any other blood got clot then we have another blood circulation going to the same spots
What is the middle cerebral artery (MCA)?
its the one that goes through the deep structures like basal ganglia, and subcortical white matter and supplies blood to the LATERAL surface of the hemisphere
what happens if theres a clot in the MCA?
you get contralateral face and arm weakness and aphasia in the left hemisphere and neglect in the right hemisphere
Where does the Anterior Cerebral Artery supply blood to?
it supplies blood to the medial surface of the hemisphere and causes contralateral leg weakness or numbness
What is a large artery/cortical stroke?
can be proximal (over a small area) or distal (spread over larger area)
- symptoms include: contralateral weakness, neglect (right hemisphere), aphasia/dysphasia (left hemisphere) and contralateral visual loss
what are sub-cortical/lacunar strokes?
occlusions of small artery that penetrates deep into the brain
- harder to detect on CT scans and MRI is often used
most common symptom of this is contralateral weakness
What is a sub cortical stroke affecting the white matter?
this affects the internal capsule of the legs, arms, and face
symptoms can include contralateral weakness affecting the face, arm and leg and even a small stroke can be debilitating
What composes of the posterior circulation?
vertebral and basilar arteries supply posterior and medial regions of the hemispheres, brainstem, diencephalon, and cerebellum
what are the two major branches of the posterior circulation?
- posterior cerebral artery
2. cerebellar arteries
what is a brainstem stroke?
a brainstem stroke is a stroke in the brain stem and the brain stem contains more wiring downstream from the internal capsule white matter that controls the movement of legs, face and arm
symptoms of this include lacunar syndrome which is weak and ataxic on the contralateral side
can lead to hemipalegia
what is a posterior cerebral artery stroke?
its a contralateral hemianopsia (blindness on one side of the visual field)
What is Locked In Syndrome?
its a stroke in the pons.
it is the ONLY stroke with bilateral symptoms
its an occlusion of the basal artery and shows differences in consciousness and leaves you quadriplegic … you are awake but you can’t move
what is transient ischemic attack (TIA)?
- these are mini strokes
- symptoms of stroke that resolve within 24 hours of onset (stroke and TIA are a continuum)
- this is a warning sign for a major stroke
these are NOT benign and 50 percent of TIA’s are associated with permanent damaged particularly if symptoms last over an hour
its a little occlusion but resolves spontaneously however can lead to permanent damage
Where do thromboembolism clots come from?
magnetic resonance angiograms are used to spot out clots in the artery
- the heart (cardioemobolic)
- arteries in the neck
- arteries in the brain
what is the major stroke mechanism?
major mechanism for stroke is unknown but 20% is from cardioembolic (travelled from heart), 20% is from large vessel atheromatous (in the neck or arteries of clotting), 25% is from small vessels and 5% from other
What is the number one cause of stroke?
irregular heartbeat via atriofibrillation (most clots go up the brain) and will end up in the left hemisphere (dominant side) and cause aphasias mostly
what is carotid artery atherosclerosis?
its when theres a plaque in the internal carotid artery and that plaque travels to the brain … can be viewed under angiogram
what is intracranial atheroscelotic disease?
arteries get stiff and non compliant and occlude
what are 4 ways to prevent stroke?
- high blood pressure treatment (drugs)
- smoking cessation
- aspirin (low dose)
- anticoagulation (warfarin or other newer drugs) only for patients with atrial fibrillation
what is cerebral schema?
insufficient blood supply (therefore low oxygen and low glucose) to meet the metabolic demands of the brain
What is the Ischmic Penumbra done by Astrup et al (1981)
studied how the brain responds to low blood in baboons
- blood flow stopped and no protein was made
- EEG became silent in that part of the brain
- blood flow is so low, you can’t bring neurons back…
- blood flow stopped and no protein was made
after its 50% low of blood flow, neurons are not dormant anymore, they just die and can’t be revived
what is the penumbric tissue?
its an area where theres an intermediate between non-functioning but still alive neurons and capable of recovery (not at 50% yet).. .kind of dormant
What are some treatment options for acute thrombus?
thrombolysis activating drug (breaks down blood clots) called tPA (tissue plasminogen activator) which activates enzymes to break down blood clot
how does tPA work?
it opens arteries and restore blood flow to the brain
What is a Hemorrhagic stroke or Intracranial hemorrhage (ICH)?
its the second most common stroke type (10-20% varies with population) and occurs mainly in african and asian populations
what is the prognosis in ICH and what does it matter on?
early 30 day case fatality is 40% and its double that of ischemic stroke
- initial level of consciousness + hematoma volume predicts death (swelling of clotted blood in the tissue)
- drowsy/coma + hematoma cause a more than 60% mortality rate
- being alert + hematoma (that is less than 30mL) cause 17% mortality rate
Initial level of consciousness + hematoma volume of more than 60mL is 91% predicts death
What are risk factors for developmental aneurysms?
aneurysms are ruptures that cause subarchanoid hemmorage
- hypertension
- smoking
- family history
How are aneurysms typically treated?
using a aneurysm coil (endovascular coil) or a surgical clip
What is the intracererbral hemorrhage treatment?
no proven therapy
