Given the disease burden of<unk> s, prevention is an important public health concern. Primary prevention is less effective than secondary prevention (as judged by the number needed to treat to prevent one<unk>  per year). Recent guidelines detail the evidence for primary prevention in<unk> . In those who are otherwise healthy, aspirin does not appear beneficial and thus is not recommended. In people who have had a myocardial infarction or those with a high cardiovascular risk, it provides some protection against a first<unk> . In those who have previously had a<unk> , treatment with medications such as aspirin, clopidogrel, and dipyridamole may be beneficial. The U.S. Preventive Services Task Force (USPSTF) recommends against screening for carotid artery<unk> enosis in those without symptoms. Risk factors The most important modifiable risk factors for<unk>  are high blood pressure and atrial fibrillation although the size of the effect is small; 833 people have to be treated for 1 year to prevent one<unk> . Other modifiable risk factors include high blood cholesterol levels, diabetes mellitus, end-stage kidney disease, cigarette smoking (active and passive), heavy alcohol use, drug use, lack of physical activity, obesity, processed red meat consumption, and unhealthy diet. Smoking just one cigarette per day increases the risk more than 30%. Alcohol use could predispose to ischemic<unk> , as well as intracerebral and subarachnoid hemorrhage via multiple mechanisms (for example, via hypertension, atrial fibrillation, rebound thrombocytosis and platelet aggregation and clotting disturbances). Drugs, most commonly amphetamines and cocaine, can induce<unk>  through damage to the blood vessels in the brain and acute hypertension. Migraine with aura doubles a person's risk for ischemic<unk> . Untreated, celiac disease regardless of the presence of symptoms can be an underlying cause of<unk> , both in children and adults. High levels of physical activity reduce the risk of<unk>  by about 26%. There is a lack of high quality<unk> udies looking at promotional efforts to improve lifestyle factors. Nonetheless, given the large body of circumstantial evidence, best medical management for<unk>  includes advice on diet, exercise, smoking and alcohol use. Medication is the most common method of<unk>  prevention; carotid endarterectomy can be a useful surgical method of preventing<unk> . Blood pressure High blood pressure accounts for 35–50% of<unk>  risk. Blood pressure reduction of 10 mmHg systolic or 5 mmHg diastolic reduces the risk of<unk>  by ~40%. Lowering blood pressure has been conclusively shown to prevent both ischemic and hemorrhagic<unk> s. It is equally important in secondary prevention. Even people older than 80 years and those with isolated systolic hypertension benefit from antihypertensive therapy. The available evidence does not show large differences in<unk>  prevention between antihypertensive drugs—therefore, other factors such as protection against other forms of cardiovascular disease and cost should be considered. The routine use of beta-blockers following a<unk>  or TIA has not been shown to result in benefits. Blood lipids High cholesterol levels have been inconsistently associated with (ischemic)<unk> .<unk> atins have been shown to reduce the risk of<unk>  by about 15%. Since earlier meta-analyses of other lipid-lowering drugs did not show a decreased risk,<unk> atins might exert their effect through mechanisms other than their lipid-lowering effects. Diabetes mellitus Diabetes mellitus increases the risk of<unk>  by 2 to 3 times. While intensive blood sugar control has been shown to reduce small blood vessel complications such as kidney damage and damage to the retina of the eye it has not been shown to reduce large blood vessel complications such as<unk> . Anticoagulation drugs Oral anticoagulants such as warfarin have been the mainstay of<unk>  prevention for over 50 years. However, several<unk> udies have shown that aspirin and other antiplatelets are highly effective in secondary prevention after a<unk>  or transient ischemic attack. Low doses of aspirin (for example 75–150 mg) are as effective as high doses but have fewer side effects; the lowest effective dose remains unknown. Thienopyridines (clopidogrel, ticlopidine) might be slightly more effective than aspirin and have a decreased risk of gastrointestinal bleeding, but are more expensive. Both aspirin and clopidogrel may be useful in the first few weeks after a minor<unk>  or high risk TIA. Clopidogrel has less side effects than ticlopidine. Dipyridamole can be added to aspirin therapy to provide a small additional benefit, even though headache is a common side effect. Low-dose aspirin is also effective for<unk>  prevention after having a myocardial infarction. Those with atrial fibrillation have a 5% a year risk of<unk> , and this risk is higher in those with valvular atrial fibrillation. Depending on the<unk>  risk, anticoagulation with medications such as warfarin or aspirin is useful for prevention. Except in people with atrial fibrillation, oral anticoagulants are not advised for<unk>  prevention—any benefit is offset by bleeding risk. In primary prevention, however, antiplatelet drugs did not reduce the risk of ischemic<unk>  but increased the risk of major bleeding. Further<unk> udies are needed to investigate a possible protective effect of aspirin against ischemic<unk>  in women. Surgery Carotid endarterectomy or carotid angioplasty can be used to remove atherosclerotic narrowing of the carotid artery. There is evidence supporting this procedure in selected cases. Endarterectomy for a significant<unk> enosis has been shown to be useful in preventing further<unk> s in those who have already had one. Carotid artery<unk> enting has not been shown to be equally useful. People are selected for surgery based on age, gender, degree of<unk> enosis, time since symptoms and the person's preferences. Surgery is most efficient when not delayed too long—the risk of recurrent<unk>  in a person who has a 50% or greater<unk> enosis is up to 20% after 5 years, but endarterectomy reduces this risk to around 5%. The number of procedures needed to cure one person was 5 for early surgery (within two weeks after the initial<unk> , but 125 if delayed longer than 12 weeks. Screening for carotid artery narrowing has not been shown to be a useful test in the general population.<unk> udies of surgical intervention for carotid artery<unk> enosis without symptoms have shown only a small decrease in the risk of<unk> . To be beneficial, the complication rate of the surgery should be kept below 4%. Even then, for 100 surgeries, 5 people will benefit by avoiding<unk> , 3 will develop<unk>  despite surgery, 3 will develop<unk>  or die due to the surgery itself, and 89 will remain<unk> -free but would also have done so without intervention. Diet Nutrition, specifically the Mediterranean-style diet, has the potential for decreasing the risk of having a<unk>  by more than half. It does not appear that lowering levels of homocysteine with folic acid affects the risk of<unk> . A Centers for Disease Control and Prevention public service announcement about a woman having a<unk>  after pregnancy. Women A number of specific recommendations have been made for women including taking aspirin after the 11th week of pregnancy if there is a history of previous chronic high blood pressure and taking blood pressure medications during pregnancy if the blood pressure is greater than 150 mmHg systolic or greater than 100 mmHg diastolic. In those who have previously had preeclampsia other risk factors should be treated more aggressively. Previous<unk>  or TIA Keeping blood pressure below 140/90 mmHg is recommended. Anticoagulation can prevent recurrent ischemic<unk> s. Among people with nonvalvular atrial fibrillation, anticoagulation can reduce<unk>  by 60% while antiplatelet agents can reduce<unk>  by 20%. However, a recent meta-analysis suggests harm from anticoagulation<unk> arted early after an embolic<unk> .<unk>  prevention treatment for atrial fibrillation is determined according to the CHA2DS2–VASc score. The most widely used anticoagulant to prevent thromboembolic<unk>  in people with nonvalvular atrial fibrillation is the oral agent warfarin while a number of newer agents including dabigatran are alternatives which do not require prothrombin time monitoring. Anticoagulants, when used following<unk> , should not be<unk> opped for dental procedures. If<unk> udies show carotid artery<unk> enosis, and the person has a degree of residual function on the affected side, carotid endarterectomy (surgical removal of the<unk> enosis) may decrease the risk of recurrence if performed rapidly after<unk> .
Stroke
Hypoglycemia
Epilepsy
Hypertensive encephalopathy
Subarachnoid hemorrhage
Giant cell arteritis
Migraine 
Bell's palsy