Epidemiology, Mechanisms & Clinical Description of Stroke

Michael R. Jaff, DO, FACP, FACCDirector, Vascular Medicine

Massachusetts General HospitalBoston, Massachusetts

Michael R. Jaff, DOConflicts of InterestMichael R. Jaff, DOConflicts of Interest

ConsultantCordis Endovascular (Modest)Boston Scientific (Modest)Medtronic Vascular (Modest)Pathway Medical (Modest)Paragon IP (Modest)X-Tent, Inc (Modest)Harvard Clinical Research Institute (Modest)Bacchus Vascular, Inc (Modest)Baxter, Incorporated (Modest)ActivBiotics (Modest)

EquityAccess Closure, Inc (Modest)Square One, Inc (Modest)Vascular Therapies, Inc (Modest)Icon Interventional, Inc (Modest)Setagon (Modest)I.C.Sciences, Incorporated (Modest)

Speaker’s BureauBristol-Myers/Sanofi-Aventis Pharmaceuticals Partnership (Modest)

Research SupportPfizer, Inc.Abbott VascularGenzyme

June, 2007

Rate of Deaths Due to Atherosclerosis is Increasing in U.S.

JAMA 2005;294:1255.

The Worldwide Stroke Pandemic

695,000

348,000

685,000316,000

468,000604,000

554,000

1,647,000

887,000

700,000

Burden of Stroke in the U.S.

1 stroke every 45 seconds (700,000 per year)2.4 million non-institutionalized stroke survivorsStroke causes 1 in 15 deathsApproximately 30 % aged 70-80 have silent brain infarction Stroke cost= 58.8 billion/year

Prevalence of Survivors of Various Disabling Neurologic Conditions

0 0.5 1 1.5 2 2.5 3 3.5

Stroke

Epilepsy

Alzheimer's

Parkinson's

What is a Stroke?

Reduction in arterial blood flow to the brain, resulting in ischemia to the brain itselfThe brain has geographic territories responsible for our higher functions

Transient Ischemic Attack (TIA)

15% of all strokes are heralded by a TIA. 1/3 of TIAs would be infarction based on diffusion weighted MRI findings. Males and blacks have higher rates of TIA.Half fail to report TIA to their healthcare providers. 90-day risk of stroke is 3-17% after TIA, highest within the first 30 days.Carotid-associated TIA: 20% 90-day stroke risk

Carotid Artery Disease: TIA

Duration <24 h, usually <15 minSymptoms:

motor and sensory dysfunction of contralateral limbspure sensory dysfunctionisolated dysphasiatransient monocular blindness

TIAs Cause Early Stroke and Cardiovascular Events

Follow up of 1707 subjects diagnosed with TIA in ED

Risk Factors for Events:OR

Age > 60 y 1.8Diabetes 2.0>10 Min TIA 2.3Weakness 1.9Speech 1.5

JAMA. 2000;284:2901-2906

Territories of the Middle Cerebral Artery

The Vascular Supply to the Brain is Rich, But Vulnerable!

Intracranial Anatomy

Vascular Territories and Stroke Syndromes

What Are the Common Causes of Stroke?

Ischemic (80%)ThrombosisEmbolism

Hemorrhagic (20%)IntracerebralSubarachnoid

Stroke Subtype Frequency

Furie KL, Kistler JP, NEJM 2000

Frequency of Stroke Types

Artery to Artery Embolism

Does Risk of Stroke Increase with Greater Degrees of ICA Stenosis?

696 Patients evaluated with Carotid Duplex Ultrasonography369 Male/327 Female

Mean Age 64 yearsMean Follow-Up 41 monthsDuplex Ultrasonography Categories

Mild <50% StenosisModerate 50-75% StenosisSevere >75% Stenosis

Stroke 1991;22:1485

Vascular Risk of Asymptomatic Carotid Stenosis

Category N TIA CVA CardiacEvent

VascularDeath

<50% 303 1 1.3 2.7 1.8

50-75% 216 3 1.3 6.6 3.3

>75% 177 7.2 3.3 8.3 6.5

75% of Events were Ipsilateral to the StenosisStroke 1991;22:1485

What Can the Physical Exam Tell You About the Etiology of Stroke?

Atrial Fib/Flutter, Bradycardia Likely Cardiogenic EmbolusNo pulse below knee Recurrent systemic embolusCarotid Bruit Severe Extracranial Carotid

StenosisHead/Orbital Bruit AV MalformationFever and Acute CVA Endocarditis and Cardiogenic

EmbolusStroke and Altered MS Check Glucose, EtOH,

Narcotics, O/D, other Toxins

Cervical Bruit

Marker of systemic atherosclerosisNot indicative of severity of internal carotid artery stenosis

NASCET: Sensitivity 63%/Specificity 61%Frequency of Cervical Bruits

~1-3% in adults aged 45-54 years~8% in adults >75 years

Bruit and Carotid Artery Disease

Presence of Bruit Increases Likelihood of Carotid Disease

020406080

100

StrokewithBruit

TIA withBruit

Bruit Control

35-75% Stenosis >75% Stenosis

Zhu, CZ. Stroke 1990;21:1131-1134

Carotid ultrasound evaluation in 261 pts with ischemic CVA, 813 pts with carotid TIAs, 500 pts with asymptomatic neck bruits, and 500 controls.

Causes of Cervical Bruit (Systolic, Diastolic, or Both)

Carotid atherosclerosisThyrotoxicosisTransmitted cardiac murmur

Aortic Stenosis (systolic)Aortic Insufficiency (diastolic)

Arteriovenous Fistula (systolic/diastolic)Venous Hum (systolic or systolic/diastolic)

Once in an ED, You Must Get an Imaging Test IMMEDIATELY!

Classic Wedge-Shaped Acute Right MCA Stroke

Important Characteristics of the CT Scan

Within 3 hours of onset of ischemia, the CT without contrast is virtually normalAfter 6-12 hours, there is evidence of hypodensity with brain edemaHemorrhage

Appearance will describe type– Subdural Hematoma: Crescent shape below dura– Subarachnoid Hemorrhage: Diffuse blood pattern along

surface of brain in subarachnoid space5% of SAH have NORMAL CT!!! MUST perform Lumbar PunctureDiscern between SAH and traumatic LPRBC Count in 4 tubes all similarXanthochromic Supernatant---old RBCs consistent with SAH

MRI Demonstrating Acute Right MCA CVA

National Institutes of Health Stroke Scale (NIHSS)

Systematic clinical assessment tool Designed in 1983 to standardize and document a reliable, valid neuro assessmentMeasures neurologic deficits

Does not assess function5-8 minutes to completeScores range from 0-42 11 items tested

http://www.ninds.nih.gov/doctors/stroke_scale_training.htm

What if Patient Has Altered Mental Status?

Glasgow Coma Scale

Eye OpeningSpontaneous…4In response to speech…3In response to pain…2None…1

Best Verbal ResponseOriented…5Confused…4Inappropriate Words…3Incomprehensible…2None…1

Best Motor ResponseObeys…6Localizes…5Withdraws…4Abnormal Flexion…3Abnormal Extension…2None…1

Glascow Coma Scale

Stroke Prevention Strategies

Reduction in Blood PressureCessation of Tobacco UseReduction in Serum CholesterolAggressive Glycemic ControlAntiplatelet TherapyRevascularization of Carotid Stenosis