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



What Is Stroke ?

Astroke

occurs when blood flowto the brain is interrupted by

a blocked or burst blood vessel.



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



Two Major Types of Stroke



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.



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



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)



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



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



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



Pathogenesis of Ischaemic Stroke

Penumbra

Infarction



Ischemic Penumbra: Current Concept



Risk Factors

Importance:

Identifying those at greatest risk forstroke

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

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



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, anteriorcommunicating,

middle cerebral,posteriorcommunicating




Anterior Circulation




Posterior Circulation



Brain Structures and Functions



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.



Ischemic Stroke: Atherothrombosis

Thrombotic

Acute occluding clot

Superimposed on chronic

narrowing



Ischemic Stroke: Cerebral Embolism Embolic

Intravascular material, most often a

clot, separates proximally

Flows through arterial system untilit occludes distally

Atrial fibrillation



Lacunar Syndromes



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%



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)



LocalizationCarotid territory

Amaurosis fugax

Dysphasia

Hemiparesis

Hemi-sensory loss

Vertebrobasilar

Hemianopia

Quadraparesis

Cranial N dysfunction

Cerebellar syndrome Crossed deficit

Loss of consciousness



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



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



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.



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



CT: Cerebral infarction

Brain swelling

Ventricular compression

Focal cortical effacement



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



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



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



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.



Diagnosis: Vascular ImagingCarotid Ultrasound Cerebral Angiography



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



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



Stroke Therapy: Overview Risk Factors:

Lifestyle modification

Risk factor management

Acute stroke therapy

Prevention of stroke: Primary prevention

Secondary prevention



Management of Risk Factors Non-pharmacological intervention:

Life style modification: cessation of smoking,

drinking

Exercise, weight reduction

Pharmacological intervention:

DM, HTN, hyperlipidemia, cardiac diseases,



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



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

stroke an overview

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