Stroke and TIA Flashcards
How common are strokes in US?
- 3rd leading cause of death in US
- major cause of adult disability
- about 800,000 people in US have a stroke each year
- on avg, one American dies from a stroke q 4 minutes
Definition of a stroke?
2 main types?
- alteration of cerebral blood flow
either from:
brain ischemia: thrombosis, embolism, or systemic hypo perfusion
or
brain hemorrhage: intracerebral hemorrhage or SAH
source of anterior circulation of the brain?
- from internal carotid
- majority of blood flow to the brain
Source of posterior circulation of the brain?
- verterbal-basilar
Cardiac sources of ischemic stroke?
- a fib
- ASD/VSD
- recent AMI
- endocarditis
- cardiac tumor
- valvular disorder
What is the most common stroke type?
- ischemic stroke
Other etiologies of strokes?
- atherosclerotic plaques (emboli from rupture, lack of perfusion from stenosis of vessels)
- vasculitis
- prothrombotic state
- cerebral hemorrhage (20% of strokes)
How is a-fib a source of a stroke?
- how does anticoag help this? aspirin?
- embolization of intracardiac thrombi
- most commonly from left atrial appendage
- anticoagulation decreases the risk of stroke by up to 70%
- aspirin decreases risk by 20-25%
Atrial and ventricular septal defects - source of stroke?
atrial:
- if assoc with R to L shunt can cause stroke
- patent foramen ovale: present in about 25% of general population, surgical or percutaneous closure
ventricular:
if assoc with R to L shunt can cause stroke
MI - as source of stroke?
- most common in pts after anterior wall infarction
- left ventricular wall mural thrombi:
large infarctions, LV dilation, CHF
Endocarditis source of stroke?
- emboli from vegetations
Cardiac tumor as a source of stroke?
- obstruction of blood flow
- can lead to arrhythmias (like a-fib)
- embolization of tumor fragments
Valvular disorders as a source of a stroke?
- native valves: rheumatic mitral stenosis is most commonly assoc with stroke
- MVP: may have fibrinious deposits on valve
- prosthetic heart valves: mechanical valves require lifelong anticoag
- repaired cardiac valves: require only anticoag short term
How common is hemorrhagic stroke?
20% of al strokes
- spontaneous intracerebral hemorrhage (10%)
- SAH - other 10%:
intracranial aneurysm, and arteriovenous malformations
What are the causes of spontaneous intracerebral hemorrhage?
- assoc with poorly controlled HTN: commonly located in basal ganglia and less commonly in pons, thalamus, cerebellum or cerebral white matter
- lacunar infarcts are assoc with HTN or DM
- bleeding disorders
- amyloid angiopathy: amyloid deposits lead to weakening of cerebral blood vessels resulting in a stroke
Causes of SAH?
- trauma
- spontaneous SAH is usually related to a ruptured AVM or aneurysm
- abnorm vascular composition (amyloid angiopathy or dissection)
- illict drug use such as cocain or amphetamines
- intracranial arterial dissections
- 20% may have no ID cause
Most common site for intracranial aneurysm? What determines the risk of rupture?
- most commonly located in circle of willis
- aneurysm is usually asx until rupture
- size and location determine risk of rupture: in general size over 1 cm carries a high risk of rupture
What is an arteriovenous malformation (AVM)?
- abnormal arterial to venous connection
- arteries and veins are tangled up - veins are under high pressure which leads to rupture
- also assoc with risk of seizure
- occurs in 0.01% of population, 1-2% of all strokes and 9% of SAH
- may be assoc with heredirary hemorrhagic telangiectasia (HHT; osler-weber-rendu syndrome)
Subtypes of strokes?
- hemorrhagic:
intracerebral hemorrhage
SAH - ischemic:
anterior circulation
posterior circulation
lacunar
What is an intracerebral hemorrhage? Major causes?
- arterial bleeding directly into the brain parenchyma
- major causes:
HTN, trauma, bleeding disorder, amyloid angiopathy, illicit drug use, AVMs - accum of blood over minutes to hours forming a localized hematoma
- *** neuro sxs increase gradually as hematoma grows
- brain tissue is destroyed as hematoma enlarges, pressure created by blood and surrounding brain edema is life-threatening
- large hematomas have a high mortality and morbidity
- goal of tx is to contain and limit the bleeding
2 main causes of SAH? What is happening?
- ruptured aneurysm (most common) or AVM
- bleeding into CSF and space surrounding brain
- aneurysm bleeds into CSF under arterial pressure and increased the ICP (this causes sxs)
- bleeding lasts a few seconds but rebleeding is common
Main tx goal of SAH?
- Identification of source of bleeding and tx before rebleeding occurs
- other goal of tx is to prevent brain damage due to delayed ischemia related to vasoconstriction of intracranial arteries: blood within the CSF induces vasoconstriction which can be intense and severe (can cause another stroke!)
2/3 of all ischemic strokes affect what circulation in the brain? 2 main arteries of this circulation?
- anterior circulation
- MCA and ACA
What is the most commonly affected vessel in ischemic strokes?
- MCA: 96% of all anterior circulation strokes (due to direct flow from internal carotid artery and its large size)
- 3% in ACA
- 1% in entire ICA distribution
What arteries would be involved in posterior circulation stroke?
What areas of the brain does this supply?
- verterbral artery
- basilar artery
- posterior cerebral artery
- blood supply to posterior portion of brain, including occipital lobes, cerebellum, and brainstem
Outcomes of posterior circulation strokes?
- terrible!
- 20% of all strokes
- 20-60% have unfavorable outcomes
- basilar artery occlusion: 90% mortality, 8-14% of all posterior circulation strokes
What are lacunar strokes?
- small lesions (less than 5 mm) that occur in penetrating arterioles in basal ganglia, pons, cerebellum, internal capsule, thalamus, and deep cerebral white matter
Outlook of lacunar strokes?
How do these appear on CT?
- less morbidity and mortality than other strokes
- on CT sometimes seen as “punched out hypodense areas” but sometimes no abnormalities can be seen
Anterior strokes occur from occlusion off of what artery?
- internal carotid artery or its branches
Posterior strokes occur from occlusion off of what artery?
- vertebral artery or its branches
HTN may cause what tpye of strokes?
- intracerebral hemorrhages or lacunar infarcts from small vessel occlusion
Stroke RFs?
- HTN
- DM
- hyperlipidemia
- cigarette smoking
- cardiac disease
- elevated blood homcysteine levels
- AIDs
- recreational drug abuse
- heavy alcohol consumption
- family hx of stroke
- overweight
- ischemic heart disease
- PVD
- sedentary lifestyle
- men older than 45 and women older than 55
- OCPs combined with smoking
- hypercoagulopathy
- polycythemia
- prior stroke
- sleep apnea (causes pro-thrombotic state while sleeping)
- bleeding disorders
What is aphasia?
- acquired communication disorder
- impairs ability to process language but doesn’t affect intelligence
- impairs ability to speak and understand others
- experience diffciculty reading and writing
Types of aphasia?
- global
- anomic
- broca’s
- wernicke’s
Global aphasia?
- most severe form
- produce few recognizable words
- understands little or no spoken speech
- can neither read or write