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Transcript of Stroke an Overview
7/27/2019 Stroke an Overview
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Stroke: An Overview
台北榮民總醫院 神經醫學中心 神經血管科
許立奇 醫師
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What Is Stroke ?
Astroke
occurs when blood flowto the brain is interrupted by
a blocked or burst blood vessel.
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Definition of Stroke
Stroke (Cerebrovascular accident, CVA): rapidlydeveloping clinical signs of focal or global disturbanceof cerebral function, with symptoms lasting 24 hours
or longer, or leading to death, with no apparent causeother than a vascular origin
WHO, 1976
Stroke definition by time course:
Transient ischemia attack (TIA): ischemic events < 24 hours without apparent permanent neurological deficits
Stoke in evolution: progressive neurological deficits overtime suggesting a widening of the area of ischemia
Completed stroke: ischemic event with persisted deficit
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Two Major Types of Stroke
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Stroke SubtypesIschemic Stroke (83%)Hemorrhagic Stroke (17%) Atherothrombotic
Cerebrovascular
Disease (20%)
Embolism (20%)Lacunar (25%)
Small vessel disease
Cryptogenic and
Other Known
Cause (30%)
Intracerebral
Hemorrhage (59%)
Subarachnoid Hemorrhage (41%)
Albers GW, et al. Chest . 1998;114:683S-698S.
Rosamond WD, et al. Stroke. 1999;30:736-743.
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Epidemiology ( I ): Global Burden
15 million nonfatal stroke each year in the world
Second leading cause of death: 5 million each year
Major cause of permanent disability: another 5
million each year
Risk of stroke: age- and sex-dependent
Incidence: varies with geography 388/100,000 in Russia, 247/100,000 in China to
61/100,000 in Fruili, Italy
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Epidemiology ( II ): Taiwan
The second leading cause of death
Incidence: average annual incidence offirst-ever stroke in Taiwan aged 36 years
old or over is 300/100,000 (CI: 71%, ICH:
22%, SAH: 1%,others: 6%) Prevalence: 1,642/100,000 (>36 years old)
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Pathophysiology of Ischemic Brain
Injury Brain:
2% of human body’s mass
20% of cardiac output Inadequate perfusion: tissue death and functional
deficit
Ischemic brain injury:
A series of interlocking thresholds – the “ ischemic
thresholds ”
Decrement in regional CBF key pathologic events
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Effects of Reduced CBF
Normal
ml/100g/mi
n
50 – 55 25 20 15 8
Ischemia
Edema Loss of Na/K+
electrical pump
↑lactate activity failure; ↓ATP
PenumbraInfarction
CellDeath
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Pathophysiology of Ischemic Brain
Injury
Topography of focal ischemia
Flow gradient: heterogeneous regional CBF reductionafter focal ischemia
Densely ischemia region surrounded by areas of less
severe CBF reduction
Ischemic penumbra: an area of reduced perfusionsufficient to cause potentially reversible clinical
deficits but insufficient to cause disrupted ionic
homeostasis
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Pathogenesis of Ischaemic Stroke
Penumbra
Infarction
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Ischemic Penumbra: Current Concept
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Risk Factors
Importance:
Identifying those at greatest risk forstroke
Providing targets for preventative
therapies
Types:
Modifiable
Non-modifiable
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Stroke: Non-modifiable Risk
factors Age
Sex Ethnicity
Prior stroke
Heredity
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Stroke: Well-Documented and
Modifiable Risk Factors
Hypertension
Diabetes
Dyslipidemia
Atrial fibrillation
Other cardiac conditions Cigarette smoke
Asymptomatic carotid
stenosis
Sickle cell disease
Postmenopausal hormone
therapy
Diet and nutrition
Physical Inactivity
Obesity and body fat
distribution
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Modifiable Risk Factors: Others
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Classification of Ischemic Stroke
By vascular territory
Ant. Circulation: carotid
arteries
Post. Circulation: VB system By stroke etiology
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Blood Supply to the Brain:
Anterior Circulation
Int. Carotid A.
arises from common
carotid a. Branches: anterior
cerebral, anteriorcommunicating,
middle cerebral,posteriorcommunicating
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Blood Supply to the Brain:
Anterior Circulation
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Blood Supply to the Brain:
Posterior Circulation
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Brain Structures and Functions
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What Is the Cause of Ischemic
Stroke? Atherothrombosis
Embolus:
Material: Red (fibrin rich) or White (plateletrich)
Source: Cardiac? Aortic? Carotid Artery?
Small artery disease Hypoperfusion: Hemodynamic
Others: arterial dissection, arteritis, etc.
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Ischemic Stroke: Atherothrombosis
Thrombotic
Acute occluding clot
Superimposed on chronic
narrowing
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Ischemic Stroke: Cerebral Embolism Embolic
Intravascular material, most often a
clot, separates proximally
Flows through arterial system untilit occludes distally
Atrial fibrillation
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Lacunar Syndromes
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Ischemic Stroke Subtypes: Data from
Taiwan Stroke Registry (2010)
Subtypes Total
Large artery atherosclerosisSmall vessel disease
Cardioembolism
Other specific etiologies
Undetermined etiologies
27.7%37.7%
10.9%
1.5%
22.3%
Total 100%
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Stroke Warning Signs Sudden weakness or numbness of the face, arm or
leg, especially on one side of the body
Sudden confusion, trouble speakingor understanding
Sudden trouble seeing in one or both eyes
Sudden trouble walking, dizziness/vertigo, loss of
balance or coordination Sudden, severe headaches with no known cause (for
hemorrhagic stroke)
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LocalizationCarotid territory
Amaurosis fugax
Dysphasia
Hemiparesis
Hemi-sensory loss
Vertebrobasilar
Hemianopia
Quadraparesis
Cranial N dysfunction
Cerebellar syndrome Crossed deficit
Loss of consciousness
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Laboratory Examinations
Hb, Hcr, thromb, leuc
glu, CRP, SR, CK, CK-MB, creat
APTT, TT-SPA/INR
Electrolytes, osmolarity
Urine analysis
CSF (if needed for differential diagnosis and onlyafter CT scan, if available)
Others, e.g., coagulation survey, homocysteine foryoung stroke, rheumotology/immunologyscreening
Cardiac evaluation: ECG, echocardiography
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Evaluation of the Vascular
System
Reprinted with permission from Albers GW, et al. Chest . 2001;119:300S-320S.
Penetrating arterydisease
Flow-reducingcarotid stenosis
Atrial fibrillation
Valve disease
Left ventricularthrombi
Cardiogenic
emboli
Aortic archplaque
Carotid plaque witharteriogenic emboli
Intracranialatherosclerosis
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Stroke Diagnostic Tests Brain imaging: CT, MR
Cardiac Imaging: TTE, TEE, heart monitoring
Lipid, coagulation testing
Vascular Imaging:
Noninvasive
MR angiography (MRA)
Intracranial, extracranial
CT angiography (CTA)Intracranial, extracranial
Ultrasound: Carotid, TCD
Invasive Conventional cerebral angiographyImage courtesy of Regional Neurosciences Unit,
Newcastle General Hospital, Newcastle, UK.
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Distinguishes reliably between haemorrhagic
and ischemic stroke
Detects signs of ischemia as early as 2 h afterstroke onset
Identifies haemorrhage immediately
Detects acute SAH in 95% of cases Helps to identify other neurological diseases
(e.g. neoplasms)
Diagnosis: CT Scan
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CT: Cerebral infarction
Brain swelling
Ventricular compression
Focal cortical effacement
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Multimodal CT Imaging
Perfusion Status
CT PCTCTA
CT, computed tomography; PCT, positron computed tomography; CTA, computed tomography angiography.
Images courtesy of UCLA Stroke Center.
Tissue
Status
Vessel
Status
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Ischemic stroke Hemorrhage stroke
Craniocerebral / cervical trauma
Meningitis/encephalitis
Intracranial mass
•Tumor
•Subdural hematoma
Seizure with persistent neurological signs
Migraine with persistent neurological signs
Metabolic
•Hyperglycemia (nonketotic hyperosmolar coma)
•Hypoglycemia
•Post-cardiac arrest ischemia
•Drug/narcotic overdose
Differential Diagnosis of Stroke
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Diagnosis: MRI (DWI and PWI) Acute Ischemic Stroke
Diffusion-weighted imaging (DWI) :
Detects areas of restricted diffusion of water Bright-up in acute ischemic stroke
Differentiation between new and old lesions
Perfusion-weighted imaging (PWI):
Detects abnormal tissue perfusion Diffusion-perfusion mismatch:
Area of penumbra?
Target of thrombolysis
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Multimodal MRI Imaging
Tissue
Status
Perfusion
Status
Vessel
Status
DWI PWI MRA
DWI, diffusion-weighted imaging; PWI, perfusion-weighted imaging; MRA, magnetic resonance angiography.
Images courtesy of UCLA Stroke Center.
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Diagnosis: Vascular ImagingCarotid Ultrasound Cerebral Angiography
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Management of Cerebrovascular Disease:
Current Strategies
Treatment of risk factors in large populations
Treatment of highest risk persons
Management of acute stroke
Prevention and treatment of medical and neurological
complications
Rehabilitation Prevention of recurrent stroke
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Strategies for Preventing Stroke and
Reducing Stroke Disability
First stroke
blood pressure
glucose
smoking
lipids
mass popl.
strategy
hypertension
TIA
Atrial fibrillation
other vascular disease
high risk strategy
stroke
mortality
acute treatment
Secondary
prevention
recurrent
stroke
Stroke related
disability
Rehabilitation
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Stroke Therapy: Overview Risk Factors:
Lifestyle modification
Risk factor management
Acute stroke therapy
Prevention of stroke: Primary prevention
Secondary prevention
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Management of Risk Factors Non-pharmacological intervention:
Life style modification: cessation of smoking,
drinking
Exercise, weight reduction
Pharmacological intervention:
DM, HTN, hyperlipidemia, cardiac diseases,
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Management: Improved CBF
Prevention: endarterectomy, stenting
Acute management: thrombolytics – medical andmechanical
Targeting endothelial cell functions (ACEI, calcium
blocker, statins, etc.)
Cerebral arterialstenosis/occlusion
LAA/CE/SVD/others
Decreased CBFCerebral autoregulation
(endothelial function etc)
Brain tissue
ischemia
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Antithrombotic Therapies to Prevent
Ischemic Stroke
Oral anticoagulants
Antiplatelet agents Aspirin 50-325 mg/day
Ticlopidine 250 mg twice daily
Clopidogrel 75 mg/day
Aspirin (25 mg) plus extended-release
dipyridamole (200 mg) twice a day