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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. What Is Stroke ? A stroke occurs when blood flow to the brain is interrupted by a blocked or burst blood.

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Presentation on theme: "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."— Presentation transcript:

1 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

2 What Is Stroke ? A stroke occurs when blood flow to the brain is interrupted by a blocked or burst blood vessel.

3 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 < 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

4 Two Major Types of Stroke

5 Stroke Subtypes Ischemic 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.

6 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

7 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)

8 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

9 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 Penumbra Infarction Cell Death

10 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

11 Pathogenesis of Ischaemic Stroke Penumbra Infarction

12 Ischemic Penumbra: Current Concept

13 Risk Factors Importance: Identifying those at greatest risk for stroke Providing targets for preventative therapies Types: Modifiable Non-modifiable

14 Stroke: Non-modifiable Risk factors Age Sex Ethnicity Prior stroke Heredity

15 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

16 Modifiable Risk Factors: Others

17 Classification of Ischemic Stroke By vascular territory Ant. Circulation: carotid arteries Post. Circulation: VB system By stroke etiology

18 Blood Supply to the Brain: Anterior Circulation Int. Carotid A. arises from common carotid a. Branches: anterior cerebral, anterior communicating, middle cerebral, posterior communicating

19 Blood Supply to the Brain: Anterior Circulation

20 Blood Supply to the Brain: Posterior Circulation

21 Brain Structures and Functions

22 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.

23 Ischemic Stroke: Atherothrombosis Thrombotic Acute occluding clot Superimposed on chronic narrowing

24 Ischemic Stroke: Cerebral Embolism Embolic Intravascular material, most often a clot, separates proximally Flows through arterial system until it occludes distally Atrial fibrillation

25 Lacunar Syndromes

26 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%

27 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)

28 Localization Carotid territory Amaurosis fugax Dysphasia Hemiparesis Hemi-sensory loss Vertebrobasilar Hemianopia Quadraparesis Cranial N dysfunction Cerebellar syndrome Crossed deficit Loss of consciousness

29 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

30 Evaluation of the Vascular System Reprinted with permission from Albers GW, et al. Chest. 2001;119:300S-320S. Penetrating artery disease Flow-reducing carotid stenosis Atrial fibrillation Valve disease Left ventricular thrombi Cardiogeni c emboli Aortic arch plaque Carotid plaque with arteriogenic emboli Intracranial atherosclerosis

31 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.

32 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) Diagnosis: CT Scan

33 CT: Cerebral infarction Brain swelling Ventricular compression Focal cortical effacement

34 Multimodal CT Imaging Perfusion Status CTPCT CTA CT, computed tomography; PCT, positron computed tomography; CTA, computed tomography angiography. Images courtesy of UCLA Stroke Center. Tissue Status Vessel Status

35 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

36 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

37 Multimodal MRI Imaging Tissue Status Perfusion Status Vessel Status DWIPWIMRA DWI, diffusion-weighted imaging; PWI, perfusion-weighted imaging; MRA, magnetic resonance angiography. Images courtesy of UCLA Stroke Center.

38 Diagnosis: Vascular Imaging Carotid Ultrasound Cerebral Angiography

39 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

40 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

41 Stroke Therapy: Overview Risk Factors: Lifestyle modification Risk factor management Acute stroke therapy Prevention of stroke: Primary prevention Secondary prevention

42 Management of Risk Factors Non-pharmacological intervention: Life style modification: cessation of smoking, drinking Exercise, weight reduction Pharmacological intervention: DM, HTN, hyperlipidemia, cardiac diseases,

43 Management: Improved CBF Prevention: endarterectomy, stenting Acute management: thrombolytics – medical and mechanical Targeting endothelial cell functions (ACEI, calcium blocker, statins, etc.) Cerebral arterial stenosis/occlusion LAA/CE/SVD/others Decreased CBF Cerebral autoregulation (endothelial function etc) Brain tissue ischemia

44 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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