Stroke: An Overview

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Stroke An Overview

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What Is Stroke ?

• A stroke occurs when blood flow to the brain is
  interrupted by a blocked or burst blood vessel.

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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
• Transient ischemia attack (TIA) ischemic events
  lt 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

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Two Major Types of Stroke
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Stroke Subtypes
Ischemic Stroke (83)
Hemorrhagic Stroke (17)
Atherothrombotic Cerebrovascular Disease (20)
Intracerebral Hemorrhage (59)
Cryptogenic and Other KnownCause (30)
Subarachnoid Hemorrhage (41)
Embolism (20)
Lacunar (25) Small vessel disease
Albers GW, et al. Chest. 1998114683S-698S. Rosam
ond WD, et al. Stroke. 199930736-743.
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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 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 (gt36 years old)

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Pathophysiology of Ischemic Brain Injury

• Brain
• 2 of human bodys 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
Infarction
Penumbra
Ischemia
50 55 25 20 15
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Edema Loss of Na/K
electrical pump ?lactate
activity failure ? ATP
Normal ml/100g/min
Cell Death
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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

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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 for stroke
• 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 BrainAnterior Circulation

• Int. Carotid A.
• arises from common carotid a.
• Branches anterior cerebral, anterior
  communicating, middle cerebral, posterior
  communicating

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Blood Supply to the BrainAnterior Circulation
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Blood Supply to the BrainPosterior 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 (platelet
  rich)
• 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 until it 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 atherosclerosis Small 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 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)

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Localization

• Carotid 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
  only after CT scan, if available)
• Others, e.g., coagulation survey, homocysteine
  for young stroke, rheumotology/immunology
  screening
• Cardiac evaluation ECG, echocardiography

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Evaluation of the Vascular System
Reprinted with permission from Albers GW, et al.
Chest. 2001119300S-320S.
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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 angiography

Image courtesy of Regional Neurosciences Unit,
Newcastle General Hospital, Newcastle, UK.
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Diagnosis CT Scan

• 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)

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CT Cerebral infarction
Brain swelling
Focal cortical effacement
Ventricular compression
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Multimodal CT Imaging
CT
PCT
CTA
Vessel Status
Tissue Status
Perfusion Status
CT, computed tomography PCT, positron computed
tomography CTA, computed tomography
angiography. Images courtesy of UCLA Stroke
Center.
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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

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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
DWI
PWI
MRA
Vessel Status
Perfusion Status
Tissue Status
DWI, diffusion-weighted imaging PWI,
perfusion-weighted imaging MRA, magnetic
resonance angiography. Images courtesy of UCLA
Stroke Center.
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Diagnosis Vascular Imaging

• Carotid 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
stroke mortality
blood pressure glucose smoking lipids
mass popl. strategy
acute treatment
recurrent stroke
First stroke
Secondary prevention
high risk strategy
Rehabilitation
hypertension TIA Atrial fibrillation other
vascular disease
Stroke related disability
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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
Cerebral arterial stenosis/occlusion LAA/CE/SVD/ot
hers
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.)

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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

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