Brain Circulation and Strokes Flashcards
What is a stroke?
Acute neurological impairment due to ischemia or hemorrhage.
What is the most common stroke?
Ischemic strokes.
What is an ischemic stroke?
Acute neurological deficits caused by impaired blood flow to the nervous system.
What scans are used to image strokes? Why?
MRI and CT scans, because they can detect brain density changes as well as presence of blood.
Who is more susceptible to stroke at a younger age? (M or F)
Male
Who is more susceptible to stroke at an older age? (M or F)
Female.
Through what arteries does blood flow to the brain? Which are present in the posterior plane? Which are present in the anterior plane?
2 Carotid arteries in the anterior plane. 2 Vertebral arteries in the posterior plane.
What causes impaired blood flow to the brain? (4)
- Vessel problems.
- Heart problems.
- Blood problems.
- Mitochondial disease.
What CBF level is considered normal?
60-50 ml/100g/min.
What is the threshold CBF past which synaptic transmission is halted?
20ml/100g/min.
During a stroke, what is the region of the brain that faces reversible damage that can recover with suboptimal function if CBF is restored?
The penumbra.
During a stroke, what is the region of the brain that obtains irreversible damage even when CBF is restored?
Infarct core.
At what CBF level does the infarct core develop?
12ml/100g/min.
What occurs to the brain when it is ischemic? How does this occur?
Cellular injury and death: Apoptosis Excitotoxicity from glutamate Inflammation Oxidative stress Mitochondrial dysfunction
What is the function of the BBB? What cells is it composed of?
FXN: Limit entry of blood products into the brain.
Composed: astrocytes, endothelial cells, pericytes, neurons.
What drug is used to break down an ischemic stroke blood clot? How does it do this?
tPA: converts plasminogen into plasmin to break down fibrin (clots).
What is TIA? How is it diagnosed?
Transient ischemic attack,
-Patient completely recovers within 24 hours, no infarct core present in CT or MRI.
What artery supplies most of the brain? Which region of the sensory/motor cortex does it nourish?
Middle cerebral artery; the arm.
What artery nourishes the occipital lobe?
Posterior cerebral artery.
What are the unique symptoms of an MCA ischemic stroke?
Numbness in the arms.
What are the unique symptoms of a PCA ischemic stroke?
Vision problems/blindness.
What are the unique symptoms of an ACA ischemic stroke?
Numbness in legs.
What is a lacunar stroke?
A stroke resulting from obstruction in lacunar vessels that stem from MCA. Causes defciits in the basal ganglia.
What is the treatment for an acute stroke?
- ABC: airway breathing and circulation.
- IV tPA or endovascular therapy to remove clot.
- Neuroprotective factors put in place.
How are ischemic strokes prevented?
Treatment of vascular risk factors, administrations of antiplatelets/anticoagulants.
Takeaway: treat underlying cause.
What criteria in patients best suit endovascular therapy?
- Small infarct core.
2. Large artery occlusions (not quickly broken down by tPA)
What is the most common/important cause of stroke?
Hypertension.
What is carotid atherosclerosis? How is it treated?
Plaque buildup in the carotid artery causing thrombosis; treated by carotid endarterectomy or stent.
What is a carotid/vertebral dissection? How to treat?
Occlusion of the CA or VA caused by blood clot formation due to tear in arterial wall, treated by anticoagulants/antiplatelets.
What is small vessel lacunar stroke caused by?
Hypertension and diabetes or microvascular disease.
How is small vessel lacunar stroke treated?
Antiplatelet.
What is a cardioembolic stroke? What is the most common cause/risk factor?
A clot that migrates from the heart to the brain. The highest risk factor is atrial fibrillation.
How is a cardioembolic stroke treated?
Anticoagulants
What is atrial fibrillation?
Irregular contraction of atria that encourages the formation of clot in atrium.
How do anticoagulants differ from antiplatelets?
Anticoagulants block coagulation cascade to prevent clotting, antiplatelets prevent platelets from adhesing to eachother
What is a hemorrhagic stroke?
Neurological deficit caused by bleeding occuring inside or around the brain tissue.
What are the subtypes of hemorrhagic strokes?
Epidural, subdural, subarachnoidal, intercerebral.
How do intercerebral hemorrhages present?
Similar to ischemic strokes
-headache, altered level of consciousness.
What is the main cause of IntC.H Stroke?
Hypertension.
How do subarachnoid hemorrhagic strokes present?
Sudden headache, neck stiffness, altered level of consciousness, cranial nerve 3 palsy (no pupil dilation).
What is the major cause of subarachnoid strokes?
Aneurysm ruptures.
How are aneurysms treated?
Clipping or coiling to prevent bursting.
