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
What Is Stroke ?
A stroke occurs when blood flow
to the brain is interrupted by
a blocked or burst blood vessel.
Definition of Stroke

Stroke (Cerebrovascular accident, CVA): rapidly
developing clinical signs of focal or global disturbance
of cerebral function, with symptoms lasting 24 hours
or longer, or leading to death, with no apparent cause
other than a vascular origin
WHO, 1976

Stroke definition by time course:
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Transient ischemia attack (TIA): ischemic events < 24
hours without apparent permanent neurological deficits
Stoke in evolution: progressive neurological deficits over
time suggesting a widening of the area of ischemia
Completed stroke: ischemic event with persisted deficit
Two Major Types of Stroke
Stroke Subtypes
Hemorrhagic Stroke (17%)
Intracerebral
Hemorrhage (59%)
Ischemic Stroke (83%)
Atherothrombotic
Cerebrovascular
Disease (20%)
Cryptogenic and
Other Known
Cause (30%)
Subarachnoid Hemorrhage (41%)
Lacunar (25%)
Small vessel disease
Albers GW, et al. Chest. 1998;114:683S-698S.
Rosamond WD, et al. Stroke. 1999;30:736-743.
Embolism (20%)
Epidemiology ( I ): Global Burden

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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
Epidemiology ( II ): Taiwan



The second leading cause of death
Incidence: average annual incidence of
first-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)
Pathophysiology of Ischemic Brain
Injury

Brain:



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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
Effects of Reduced CBF
Ischemia
50 – 55
Normal
ml/100g/mi
n
25
Edema
↑lactate
ATP
Infarction
Penumbra
20
15
8
Loss of
Na/K+
electrical
pump
activity
failure; ↓
Cell
Death
Pathophysiology of Ischemic Brain
Injury
Topography of focal ischemia



Flow gradient: heterogeneous regional CBF reduction
after focal ischemia
Densely ischemia region surrounded by areas of less
severe CBF reduction
Ischemic penumbra: an area of reduced perfusion
sufficient to cause potentially reversible clinical
deficits but insufficient to cause disrupted ionic
homeostasis
Pathogenesis of Ischaemic Stroke
Penumbra
Infarction
Ischemic Penumbra: Current Concept
Risk Factors

Importance:
Identifying those at greatest risk for
stroke
 Providing targets for preventative
therapies


Types:
Modifiable
 Non-modifiable

Stroke: Non-modifiable Risk
factors





Age
Sex
Ethnicity
Prior stroke
Heredity
Stroke: Well-Documented and
Modifiable Risk Factors

Hypertension

Diabetes


Asymptomatic carotid
stenosis
Sickle cell disease

Dyslipidemia

Atrial fibrillation

Other cardiac conditions

Diet and nutrition

Cigarette smoke

Physical Inactivity


Postmenopausal hormone
therapy
Obesity and body fat
distribution
Modifiable Risk Factors: Others
Classification of Ischemic Stroke

By vascular territory
Ant. Circulation: carotid
arteries
 Post. Circulation: VB system


By stroke etiology
Blood Supply to the Brain:
Anterior Circulation

Int. Carotid A.


arises from common
carotid a.
Branches: anterior
cerebral, anterior
communicating,
middle cerebral,
posterior
communicating
Blood Supply to the Brain:
Anterior Circulation
Blood Supply to the Brain:
Posterior Circulation
Brain Structures and Functions
What Is the Cause of Ischemic
Stroke?


Atherothrombosis
Embolus:

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Material: Red (fibrin rich) or White (platelet
rich)
Source: Cardiac? Aortic? Carotid Artery?
Small artery disease
Hypoperfusion: Hemodynamic
Others: arterial dissection, arteritis, etc.
Ischemic Stroke: Atherothrombosis

Thrombotic

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Acute occluding clot
Superimposed on chronic
narrowing
Ischemic Stroke: Cerebral Embolism

Embolic

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Intravascular material, most often a
clot, separates proximally
Flows through arterial system until
it occludes distally
Atrial fibrillation
Lacunar Syndromes
Ischemic Stroke Subtypes: Data from
Taiwan Stroke Registry (2010)
Subtypes
Total
Large artery atherosclerosis
Small vessel disease
Cardioembolism
Other specific etiologies
Undetermined etiologies
27.7%
37.7%
10.9%
1.5%
22.3%
Total
100%
Stroke Warning Signs

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Sudden weakness or numbness of the face, arm or
leg, especially on one side of the body
Sudden confusion, trouble speaking
or 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)
Localization
Carotid territory


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
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

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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 only
after CT scan, if available)
Others, e.g., coagulation survey, homocysteine for
young stroke, rheumotology/immunology
screening
Cardiac evaluation: ECG, echocardiography
Evaluation of the Vascular
System
Intracranial
atherosclerosis
Carotid plaque with
arteriogenic emboli
Aortic arch
plaque
Cardiogeni
c
emboli
Penetrating artery
disease
Flow-reducing
carotid stenosis
Atrial fibrillation
Valve disease
Left ventricular
thrombi
Reprinted with permission from Albers GW, et al. Chest. 2001;119:300S-320S.
Stroke Diagnostic Tests

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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
Image courtesy
Regional Neurosciences
Unit,
 ofConventional
cerebral
angiography
Newcastle General Hospital, Newcastle, UK.
Diagnosis: CT Scan

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Distinguishes reliably between haemorrhagic
and ischemic stroke
Detects signs of ischemia as early as 2 h after
stroke onset
Identifies haemorrhage immediately
Detects acute SAH in 95% of cases
Helps to identify other neurological diseases
(e.g. neoplasms)
CT: Cerebral infarction
Brain swelling
Focal cortical effacement
Ventricular compression
Multimodal CT Imaging
CT
PCT
Tissue
Status
Perfusion Status
CTA
Vessel
Status
CT, computed tomography; PCT, positron computed tomography; CTA, computed tomography angiography.
Images courtesy of UCLA Stroke Center.
Differential Diagnosis of Stroke
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
Diagnosis: MRI (DWI and PWI)

Acute Ischemic Stroke
Diffusion-weighted imaging (DWI) :

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Perfusion-weighted imaging (PWI):

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Detects areas of restricted diffusion of water
Bright-up in acute ischemic stroke
Differentiation between new and old lesions
Detects abnormal tissue perfusion
Diffusion-perfusion mismatch:

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Area of penumbra?
Target of thrombolysis
Multimodal MRI Imaging
DWI
Tissue
Status
PWI
Perfusion
Status
MRA
Vessel
Status
DWI, diffusion-weighted imaging; PWI, perfusion-weighted imaging; MRA, magnetic resonance angiography.
Images courtesy of UCLA Stroke Center.
Diagnosis: Vascular Imaging
Carotid Ultrasound
Cerebral Angiography
Management of Cerebrovascular Disease:
Current Strategies
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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
Strategies for Preventing Stroke and
Reducing Stroke Disability
blood pressure
glucose
smoking
lipids
stroke
mortality
mass popl.
strategy
acute treatment
First stroke
Secondary
prevention
recurrent
stroke
high risk strategy
hypertension
TIA
Atrial fibrillation
other vascular disease
Rehabilitation
Stroke related
disability
Stroke Therapy: Overview

Risk Factors:

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Lifestyle modification
Risk factor management
Acute stroke therapy
Prevention of stroke:

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Primary prevention
Secondary prevention
Management of Risk Factors

Non-pharmacological intervention:

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Life style modification: cessation of smoking,
drinking
Exercise, weight reduction
Pharmacological intervention:

DM, HTN, hyperlipidemia, cardiac diseases,
Management: Improved CBF
Cerebral arterial
stenosis/occlusion
LAA/CE/SVD/others

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Decreased CBF
Cerebral autoregulation
(endothelial function etc)
Brain tissue
ischemia
Prevention: endarterectomy, stenting
Acute management: thrombolytics – medical and
mechanical
Targeting endothelial cell functions (ACEI, calcium
blocker, statins, etc.)
Antithrombotic Therapies to Prevent
Ischemic Stroke


Oral anticoagulants
Antiplatelet agents

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

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