RISK FACTORSDr MOHAMMAD A S KAMIL

CONSULTANT NEUROLOGIST

NEUROSCIENCES HOSPITAL

Nonmodifiable Risk Markersfor Ischemic Stroke

• age.

• Sex.

• Race or ethnicity.

• Heredity.

Modifiable Risk Factors

• Atrial fibrillation Other cardiac diseases

• Carotid artery stenosis

• Cigarette smoking

• Diabetes mellitus

• Hyperlipidemia

• Hypertension

• Insulin resistance/metabolic syndrome

• Physical inactivity/sedentary behaviors

•Approximately 90% of strokes could be explained by 10 risk factors: hypertension, diabetes, cardiac causes, current smoking, abdominal obesity, hyperlipidemia, physical inactivity, alcohol consumption, diet, and psychosocial stress and depression.

•These risk factors may be divided into medical conditions and behavioral risk factors.

Medical risk factors.

•Hypertension : is the most important modifiable risk factor for ischemic stroke.

• Hypertension accounted for 35% to 50% of the risk of stroke, depending on the

definition used.

• Observational studies have shown an increased risk of stroke associated with all

degrees of hypertension, isolated systolic hypertension, and diastolic blood pressure.

• Recent analyses have shown that the variability in blood pressure measurements,both

from visit to visit and even among separate measurements taken within a single visit, is

associated with increased risk of stroke.

Atrial fibrillation

• Cardiac diseases are a well-recognized cause of embolic cerebral infarction .

• Certain cardiac diseases, such as atrial fibrillation (AF), recent MI, significant left ventricular dysfunction with mural thrombus, and valvular heart disease,are considered proven causes of stroke.

• Others, including patent foramen ovale (PFO), mitral valve strands, aortic arch atheroma, and left ventricular hypertrophy, have more equivocal epidemiologic evidence.

• Although AF has long been appreciated as an important cause of stroke, its relative importance has probably been underestimated, as recent studies suggest that AF may account for an even greater proportion of unexplained strokes than previously realized .

• in one study of 56 patients with unexplained stroke, outpatient cardiac telemetry for 21 days detected AF in 28% of patients. In another study of patients with a prior history of thromboembolic events without a known history of AF, the use of long-term continuous arrhythmia monitoring with an implantable device led to detection of AF in 28% of patients over an average of 1 year of monitoring.

• Additionally, because the prevalence of AF increases substantially with age, the attributable risk of stroke due to AF increases in the elderly. Among those 80 to 89 years of age, AF may be responsible for as many as 25% of strokes

Patent foramen ovale.

• The likelihood of finding a patent foramen ovale in a patient with cryptogenic stroke

can be estimated by patient age and the presence of other risk factors.

• There is a 33% overall probability that a patent foramen ovale found in a patient with

cryptogenic stroke is incidental.

Hyperlipidemia

• The relationship of lipid abnormalities to ischemic stroke has been less

certain than for heart disease.

• In a meta-analysis of 32 prospective studies on ischemic stroke

outcomes with more than 173,000 patients, non-high-density lipoprotein

cholesterol levels (ie, low-, intermediate-, and very low-density lipoprotein cholesterol)

were modestly associated with risk of ischemic stroke, whereas triglycerides and high-

density lipoprotein cholesterol were not.

• None of the lipid levels predicted hemorrhagic stroke.

• Importantly,the use of nonfasting as opposed to fasting levels did not change the

results.

Diabetes

• Diabetes is a well-recognized risk factor for

atherosclerosis and MI, as well as for microangiopathy

affecting the brain, retina, and heart.

• Diabetes mellitus may sometimes be associated with

a diffuse Cerebrovascular Microangiopathy

characterized at autopsy by swelling of endothelial

cells, the presence of multiple lamellae of basal

laminae, and multiple small infarcts.

Behavioral risk factors

Cigarette smoking: wealth of data supports the role of smoking as an important

and prevalent stroke risk factor, in addition to its other adverse effects. Smoking appears

to be a particularly strong modifier of the effect of oral contraceptives in increaseing the

risk of stroke among women with classic migraine.

Physical inactivity:

• Several observational studies have found that physical activity is associated with a

decrease in risk of stroke and that sedentary lifestyle is associated with an increased

risk. Physical activity and sedentary lifestyle are not mutually exclusive, however.

• Even those who do engage in exercise on a regular basis may spend a significant

amount of their day in sedentary activities (eg, sitting at desks, watching television,

etc.), which themselves carry risks.

• Thus, both increasing physical activity and minimizing sedentary behavior should

probably be encouraged.

Potential Risk Factors UnderContinued Investigation• Abdominal Obesity

• Alcohol Consumption

Moderate :Protective against ischemic stroke,Increases risk of hemorrhagic stroke.

Heavy or binge drinking: Increases risk of strokes

• Ankle-Brachial Blood Pressure Ratio

• Depression

• Homocysteine

• Diet: Increased risk: saturated fats, salt

Decreased risk: fruits, fish, Mediterranean diet

• Illicit Drug Use

• Infections :Chlamydia pneumonia,Helicobacter pylori,Herpesviruses,Periodontalinfection.

• Infectious Burden

• Inflammation: High-sensitivity C-reactive protein,Leukocyte count,Lipoprotein-associated ,phospholipase A 2 (LpPLA2),Other cytokines (interleukin 6,tumor necrosis factor and its receptors).

• Migraine

• MRI White MatterAbnormalities

• Oral Contraceptive Use

• Peripheral Arterial Disease

• Pollution/ParticulateMatter

• Psychosocial Stress

• Renal Disease (Decreased Function, Albuminuria)

• Snoring/Sleep Apnea

investigation

Time is brain

• Brain imaging: computed tomography (CT) Fast

Reliable, Available, Differentiates between ICH and ischaemic stroke, May show alternate

diagnosis.

• scanning or magnetic resonance imaging (MRI)

• Carotid evaluation

• Cardiac imaging: echocardiography

• Laboratory testing (routine thrombophilia screens, antiphospholipid antibodies, and

other auto-antibodies or homocysteine

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