Risk Factors
Some of the usual and unusual risk factors for stroke include
Hypertension or high blood pressure is defined as a systolic pressure of 140 or higher and a diastolic pressure of 90 or higher
Atherosclerosis is caused by high cholesterol or Dyslipidemia (high LDL Cholesterol/Triglycerides low HDL Cholestrol). Abnormalities in low-density and high-density lipoprotein-cholesterol and triglycerides are called Dyslipidemia. More information at
Diabetes Mellitus may be classified as a stroke risk equivalent and may warrant more aggressive treatment strategies in the future prevention of stroke. (Ho, Paultre , Mosca, 2003 Stroke 34(12):2812-2816). You can lower your risk of stroke if you have diabetes with
- Good blood pressure control a maximum of 120/80
- Good blood sugar control
Atrial Fibrillation - The heart’s two small upper chambers (the atria) quiver instead of beating effectively. Blood isn’t pumped completely out of them, so it may pool and clot. If a piece of a blood clot in the atria leaves the heart and becomes lodged in an artery in the brain, a stroke results. About 15 percent of strokes occur in people with atrial fibrillation. Half of all strokes associated with atrial fibrillation are major and disabling. More information at Brian Loftus MD
Tobacco Use/Cigarette smoking is an important risk factor for stroke and evidence is available that smoking cessation does reduce the individual's risk of stroke (MacWalter & Shirley 2002). “The risk of stroke in ex-smokers declines to that in non-smokers within 2 to 5 years after smoking cessation” (Pinkowish, p. 12, 1999). More information at
Obesity, especially abdominal obesity is a risk factor for myocardial infarction. Suk and colleagues in the Northern Manhattan Stroke Study, New York City, analyzed 576 cases and 1142 case controls and found a strong link between waist-hip ratio and the incidence of ischemic stroke. After adjusting for other risk factors, the odds ratio for ischemic stroke among individuals with waist-hip ratios in the highest quartile versus the lowest quartile was 4.1 for women and 2.4 for men. This finds that abdominal obesity, especially in women is an independent risk factor for ischemic stroke, even after adjusting for hypertension, diabetes, and physical inactivity
Birth Control Pills - Studies have shown an increased risk of blood clots in women taking third-generation oral contraceptives, (e.g., those containing the progestogens desogestrel or gestodene). A study looked at several types of oral contraceptives in 203 women with an ischemic stroke and 925 control women (age 18 to 49). Women with a first ischemic stroke were compared with control women without vascular diseases. All patients and control subjects filled in a questionnaire about the use of oral contraceptives and risk factors for ischemic stroke. The risk of stroke in women using any type of oral contraceptives vs. none was 2.3. Current users of first-generation oral contraceptives had an odds ratio of 1.7. Low-dose second-generation oral contraceptives increased the risk of stroke 2.4 times, and third-generation oral contraceptives increased the risk of stroke 2.0 times. The risk of stroke in women using third-generation oral contraceptives was not significantly different from that in women using second-generation oral contraceptives (odds ratio 1.0). Thus, third-generation oral contraceptives (containing desogestrel or gestodene) confer the same risk of first ischemic stroke as second-generation oral contraceptives (containing levonorgestrel). STROKE, 2002, Vol 33, Iss 5, pp 1202-1208. Conclusions Data from observational studies suggest that migraine may be a risk factor in developing stroke. More studies are needed to explore the mechanism of this potential association. In addition, the risk of migraine among users of oral contraceptives must be further investigated
Blood Clotting Disorders - There are a variety of problems that might cause the blood to clot. The most well know of these are (but there are others)
- Antiphospholipid Antibodies
- Lupus Anticoagulant
Some of the Known Blood Clotting Disorders include
- Anticardiolipin Antibodies
- Antiphospholipid syndrome (APS) currently recognized as a common risk factor for arterial or venous thromboembolic disease. These antibodies have also been associated with a range of clinical conditions including fetal loss, endocarditis, stroke, heart attack and hemolytic anemia
- Antiphospholipid antibodies are a relatively well-established risk factor for ischemic stroke, especially in people under 50
- Factor V Leiden is an inherited disorder that can lead to abnormal blood clotting (coagulation) or thrombophilia. The Factor V Leiden is the most common hereditary blood coagulation disorder in the United States. The name Factor V Leiden means that there's a mutation in the DNA in the gene used to make the Factor V protein
- Hyperhomocysteinaemia: elevated homocysteine plasma levels
- Methylenetetrahydrofolate Reductase Mutation (MTHFR): One of the most common genetic defects of homocysteine metabolism is a mutation in the enzyme MTHFR. Increased plasma homocysteine is a risk factor for arteriosclerotic vascular disease and deep-vein thrombosis
- Plasminogen deficiency: an uncommon cause of inherited thrombosis
- Protein C and Protein S: involved in regulation of coagulation (blood clotting); they inactivate factors V and VIII
- Protein C deficiency: can result in excessive clotting. These clots tend to form in veins, not arteries. This disorder can be either inherited or acquired
- Protein S deficiency: can result in excessive clotting tendencies. These are usually vein clots, such as deep vein thrombosis, but occasionally this disorder can be associated with arterial clots
- Prothrombin Gene mutation 020210: an inherited mutation that can result in blood clots. A mutation in the prothrombin gene makes the body produce too much of the prothrombin protein, resulting in an increased tendency for the blood to clot
- Thrombophilia means an increased tendency for the blood to clot
- Inherited causes of thrombophilia include: deficiencies of antithrombin, protein C and protein S; elevated Factor VIII; Factor V Leiden (activated protein C resistance); Factor II 20210A; and dysfibrinogenemia. Most of these are autosomal dominantly inherited. Hyperhomocysteinemia may be inherited or acquired and non-inherited factors influence Factor VIII levels
Tests for Hypercoagulable State: CBC, PT, PTT, Proteins C and S, Antithrombin, Factor V Leiden (and/or APC resistance), Factor VIII C, Factor II 20210 A, Fasting homocysteine, Lupus Anticoagulant and anticardiolipin antibody. More information at
The Antiphospholipid Antibodies in Stroke Study (APASS) analyzed this issue in patients enrolled in the Warfarin Versus Aspirin Recurrent Stroke Study (WARSS). Among 1770 patients with ischemic stroke who were tested for antiphospholipid antibodies, 13.4% evidenced the lupus anticoagulant, 20.5% demonstrated anticardiolipin antibodies, 6.7% showed both types, and 59.3% showed neither. Patients with either the lupus anticoagulantÊ or anticardiolipin antibodies alone had no increase in recurrent thrombotic events compared with patients without antiphospholipid antibodies. Only patients with both the lupus anticoagulant and anticardiolipin antibodies showed a higher thrombotic event rate (35.9% versus 26.2%). Systemic Lupus Erythematosus, deficiency of antithrombin III or protein S or C, resistance to activated protein C, increased factor VIII)
- Migraine - Controlled studies of patients with ischemic stroke report an association with migraine, especially in women aged less than 45 years who have a history of migraine with aura. The risk at age 40 is thought to be 36 per 100,000 women who get migraines. Conclusions: Data from observational studies suggest that migraine may be a risk factor in developing stroke. More studies are needed to explore the mechanism of this potential association. In addition, the risk of migraine among users of oral contraceptives must be futher investigated. Refer to Migraine Review.pdf
- Migrainous stroke was more common in women (67%) and in patients aged 45 years (78%) compared to the remaining ischaemic strokes of unusual cause. Patients with migrainous stroke present some different clinical features from other ischaemic strokes of unusual aetiology. Refer to Migraine 2003.pdf
Sleep Apnea- Researchers from Buffalo found that people who snore, sleep more than 8 hours a night and experience excessive daytime drowsiness have increased risk for stroke (Stroke 2001, 32:331). There are three types of sleep apne: obstructive, central, and mixed. Of the three, obstructive is the most common. People with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night and often for a minute or longer. More information at
Patent Foramen Ovale (PFO) is a hole in the atrial septal wall of the heart. A blood clot or bubble is passed through the hole from the systemic venous circulation to the systemic arterial circulation. Refer to Columbia University
Stroke databases suggest that despite intensive evaluation, approximately 40% of all patients suffering ischaemic strokes (80% of all stroke victims) remain without clearly identifiable precipitant or cause In 1989, Webster and Lechat separately reported increased prevalence of PFO in patients with cryptogenic stroke (CS). Refer to PFO Indications for closure 2004.pdf
In the recently published Controversies in Stroke on the best treatment of patients with patent foramen ovale and stroke, much emphasis is put on the association of PFO with atrial septal aneurysm as a marker of increased stroke risk as compared with PFO alone, whereas PFO size seems to be a negligible variable.
The role of paradoxical embolism through patent foramen ovale as a mechanism of cryptogenic stroke is controversial. If a venous source of emboli is relevant, prothrombotic states should be associated with patent foramen ovale and cryptogenic stroke. We assessed the occurrence of several prothrombotic states (factor V Leiden, prothrombin G20210A, deficiencies in protein S, protein C and antithrombin, lupus anticoagulant, anticardiolipin antibodies, elevated factor VIII, resistance to activated protein C) and classical risk factors for venous thrombosis in 57 adult patients with cryptogenic stroke and patent foramen ovale and in 104 matched controls. Refer to Patent Foramen Ovale.pdf
Conclusions: In this exploratory analysis, the presence of PFO in the younger cryptogenic stroke patients did not increase the risk of adverse events. However, in the older patients, PFO significantly increased the risk of adverse events. (Stroke. 2004;35:2145-2149)
Transcatheter PFO closure in patients with cryptogenic stroke and large RLS may be less successful than reported previously. (Stroke. 2004; 35:2140-2144). Refer to Proclosureshutdoor.pdf
Information on Unususal Sources: Infections
Information on Cerebral Artery Dissection
Information on Arteriovenous Malformations
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