Approach to a patient with stroke - Pathophysiology of stroke
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Approach to a patient with stroke
Ashwin HaridasAsem Ali Ashraf
Adam EAH Adam
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DefinitionsStroke
Clinical syndrome of rapid onset of focal deficits of brain function lasting more than 24 hours or leading to death
Transient Ischemic attack (TIA)Clinical syndrome of rapid onset of focal
deficits of brain function which resolves within 24 hours
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DefinitionsProgressive Stroke
A stroke in which the focal neurological deficits worsen with time
Also called stroke in evolution
Completed StrokeA stroke in which the focal neurological deficits
persist and do not worsen with time
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EpidemiologyThird most common cause of death after
cancer and ischeamic heart diseaseMost common cause of severe physical
disabilityPrevalence of stroke in India is about 1.54
per 1000Death rate is about 0.6 per 1000Incidence and prevalence of stroke is on the
rise due to increasing adoption of unhealthy lifestyle & an increasing life expectancy
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Stroke Risk FactorsFixed
AgeGender
(Male>Female)Race (Afro-
Caribbean>Asian>European)
HeredityPrevious vascular
event eg. MI, peripheral embolism
High fibinogen
ModifiableHypertensionHeart disease
(Atrial fibrillation, endocarditis)
Diabetes mellitusHyperlipidaemiaSmokingExcess alcohol
consumptionOral contraceptives
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Types of StrokeIschemicHemorrhagic
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Anterior Circulation
Posterior Circulation
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Middle Cerebral Artery
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Anterior Cerebral Artery
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Posterior Cerebral Artery
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Ischemic Stroke80% of strokesArterial occlusion of an intracranial vessel
leads to hypoperfusion of the brain region it supplies
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Etiology of ischemic strokeThrombotic
Lacunar strokeLarge vessel
thrombosisHypercoagulable
disorders
EmbolicArtery to artery
Carotid bifurcation Aortic arch
Cardioembolic Atrial fibrillation Myocardial infarction Mural thrombus Bacterial endocarditis Mitral stenosis Paradoxical embolus
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Thrombotic Stroke
Atherosclerosis is the most common pathology leading to thrombotic occlusion of blood vessels
Hypercoagulable disorders – uncommon causeAntiphospholipid syndromeSickle cell anemiaPolycythemia veraHomocysteinemia
Vasculitis: PAN, Wegener’s granulomatosis, giant cell arteritis
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Lacunar strokeAccounts for 20% of all strokesResults from occlusion of small deep
penetrating arteries of the brainPathology: lipohyalinosis & microatheromaThrombosis leads to small infarcts known as
lacunesClinically manifested as lacunar syndromes
Thrombotic Stroke
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Embolic StrokeCardioembolic stroke
Embolus from the heart gets lodged in intracranial vessels
MCA most commonly affectedAtrial fibrillation is the most common causeOthers: MI, prosthetic valves, rheumatic heart disease
Artery to artery embolismThrombus formed on atherosclerotic plaques gets
embolized to intracranial vesselsCarotid bifurcation atherosclerosis is the most comon
sourceOthers: aortic arch, vertebral arteries etc.
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Etiology of ischemic stroke
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Blood supply to the brain is autoregulatedBlood flow
If zero leads to death of brain tissue within 4-10min
<16-18ml/100g tissue/min infarction within an hour
Ischemia leads to development of an ischemic core and an ischemic penumbra
Pathophysiology of Ischemic Stroke
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Ischemic Penumbra
Tissue surrounding the core region of infarction which is ischemic but reversibly dysfunctional
Maintained by collateralsCan be salvaged if reperfused in
timePrimary goal of revascuralization
therapies
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ATP depletion
Hypoperfusion
Failure of Na+/K+ ATPase membrane ionic pump
Calcium entryGlutamate release
Activation of lipid peroxidases, proteases & NO synthase
Destruction of intracellular organelles, cell membrane & release of free radicals
Free fatty acid release
Activation of pro-coagulant pathways
Liquefactive necrosis
Thrombus/embolus
Membrane depolarization & cytotoxic cellular edema
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Hemorrhagic Stroke
Two typesIntracerebral
hemorrhage(ICH)Subarachnoid
hemorrhage(SAH)Higher mortality
rates when compared to ischemic stroke
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Intracerebral Hemorrhage• Result of chronic hypertension• Small arteries are damaged due to
hypertension• In advanced stages vessel wall is disrupted
and leads to leakage• Other causes: amyloid angiopathy,
anticoagulant therapy, cavernous hemangioma, cocaine, amphetamines
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Subarachnoid HemorrhageMost common cause is rupture of saccular or
Berry aneurysmsOther causes include arteriovenous
malformations, angiomas, mycotic aneurysmal rupture etc.
Associated with extremely severe headache
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Pathophysiology Of Hemorhagic Stroke
Explosive entry of blood into the brain parenchyma structurally disrupts neurons
White matter fibre tracts are splitImmediate cessation of neuronal functionExpanding hemorrhage can act as a mass
lesion and cause further progression of neurological deficits
Large hemorrhages can cause transtentorial coning and rapid death