Stroke

A stroke, also referred to as a cerebrovascular accident, is a medical condition in which blood flow to a part of the brain is reduced or blocked causing cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly. Signs and symptoms of a stroke may include facial drooping, inability to walk, move or feel on one side of the body, problems understanding or speaking, dizziness, or loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than 24 hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. A hemorrhagic stroke may also be associated with a severe headache. The symptoms of a stroke can be permanent. Long-term complications may include pneumonia and loss of bladder control. The biggest risk factor for a stroke is high blood pressure. Other risk factors include high cholesterol, smoking, obesity, diabetes, a previous TIA, atrial fibrillation and air pollution. An ischemic stroke is typically caused by blockage of a blood vessel, though there are also less common causes. A hemorrhagic stroke is caused by either bleeding directly into the brain or into the space between the brain's membranes. Bleeding may occur due to a ruptured brain aneurysm.…

A stroke, also referred to as a cerebrovascular accident, is a medical condition in which blood flow to a part of the brain is reduced or blocked causing cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly. Signs and symptoms of a stroke may include facial drooping, inability to walk, move or feel on one side of the body, problems understanding or speaking, dizziness, or loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than 24 hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. A hemorrhagic stroke may also be associated with a severe headache. The symptoms of a stroke can be permanent. Long-term complications may include pneumonia and loss of bladder control. The biggest risk factor for a stroke is high blood pressure. Other risk factors include high cholesterol, smoking, obesity, diabetes, a previous TIA, atrial fibrillation and air pollution. An ischemic stroke is typically caused by blockage of a blood vessel, though there are also less common causes. A hemorrhagic stroke is caused by either bleeding directly into the brain or into the space between the brain's membranes. Bleeding may occur due to a ruptured brain aneurysm. Diagnosis is typically based on a physical exam and supported by medical imaging such as a CT scan or MRI scan. A CT scan can rule out bleeding, but may not necessarily rule out ischemia, which early on typically does not show up on a CT scan. Low blood sugar may cause similar symptoms. Prevention includes decreasing risk factors, surgery to open up the arteries to the brain in those with problematic carotid narrowing, and anticoagulant medication in people with atrial fibrillation. Aspirin or statins may be recommended by physicians for prevention. A stroke is a medical emergency. Ischemic strokes, if detected within three to four-and-a-half hours, may be treatable with medication that can break down the clot, while hemorrhagic strokes sometimes benefit from surgery. Treatment to attempt recovery of lost function is called stroke rehabilitation, and ideally takes place in a stroke unit; however, these are not available in much of the world. In 2023, 13.2 million people worldwide had a stroke. Strokes were the second biggest cause of death. Some 105 million people who had previously had a stroke and were still alive. About 3.2 million deaths resulted from an ischemic stroke and 3.5 million deaths from a hemorrhagic stroke. Overall, two thirds of cases of a stroke occurred in those over 65 years old. ==Classification== stroke Stroke can be classified into two major categories: ischemic and hemorrhagic. An ischemic stroke is caused by interruption of the blood supply to the brain, while a hemorrhagic stroke results from the rupture of a blood vessel or an abnormal vascular structure. About 87% of strokes are ischemic, with the rest being hemorrhagic. Bleeding can develop inside areas of ischemia, a condition known as "hemorrhagic transformation". It is unknown how many cases of hemorrhagic stroke actually start as an ischemic stroke. ===Definition=== In the 1970s the World Health Organization defined a "stroke" as a "neurological deficit of cerebrovascular cause that persists beyond 24 hours or is interrupted by death within 24 hours", although the word "stroke" is centuries old. This definition was supposed to reflect the reversibility of tissue damage and was devised for the purpose, with the time frame of 24 hours being chosen arbitrarily. The 24-hour limit divides a stroke from a transient ischemic attack, which is a related syndrome of stroke symptoms that resolve completely within 24 hours. With the availability of treatments that can reduce the severity of a stroke when given early, many now prefer alternative terminology, such as "brain attack" and "acute ischemic cerebrovascular syndrome" (modeled after heart attack and acute coronary syndrome, respectively), to reflect the urgency of stroke symptoms and the need to act swiftly. ===Ischemic=== During an ischemic stroke, blood supply to part of the brain is decreased, leading to dysfunction of the brain tissue in that area. There are four reasons why this might happen: Thrombosis (obstruction of a blood vessel by a blood clot forming locally) Embolism (obstruction due to an embolus from elsewhere in the body), Systemic hypoperfusion (general decrease in blood supply, e.g., in shock) Cerebral venous sinus thrombosis. A stroke without an obvious explanation is termed a cryptogenic stroke (idiopathic); this constitutes 30–40% of all cases of ischemic stroke. There are classification systems for an acute ischemic stroke. The Oxford Community Stroke Project classification (OCSP, also known as the Bamford or Oxford classification) relies primarily on the initial symptoms; based on the extent of the symptoms, the stroke episode is classified as total anterior circulation infarct (TACI), partial anterior circulation infarct (PACI), lacunar infarct (LACI) or posterior circulation infarct (POCI). These four entities predict the extent of the stroke, the area of the brain that is affected, the underlying cause, and the prognosis. The TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification is based on clinical symptoms as well as results of further investigations; on this basis, a stroke is classified as being due to (1) thrombosis or embolism due to atherosclerosis of a large artery, (2) an embolism originating in the heart, (3) complete blockage of a small blood vessel, (4) other determined cause, (5) undetermined cause (two possible causes, no cause identified, or incomplete investigation). Users of stimulants such as cocaine and methamphetamine are at a high risk for an ischemic stroke. ===Hemorrhagic=== of an intraparenchymal bleed (bottom arrow) with surrounding edema (top arrow) There are two main types of hemorrhagic stroke: Intracerebral hemorrhage, which is bleeding within the brain itself (when an artery in the brain bursts, flooding the surrounding tissue with blood), due to either intraparenchymal hemorrhage (bleeding within the brain tissue) or intraventricular hemorrhage (bleeding within the brain's ventricular system). Subarachnoid hemorrhage, which is bleeding that occurs outside of the brain tissue but still within the skull, and precisely between the arachnoid mater and pia mater (the delicate innermost layer of the three layers of the meninges that surround the brain). The above two main types of hemorrhagic stroke are also two different forms of intracranial hemorrhage, which is the accumulation of blood anywhere within the cranial vault; but the other forms of intracranial hemorrhage, such as epidural hematoma (bleeding between the skull and the dura mater, which is the thick outermost layer of the meninges that surround the brain) and subdural hematoma (bleeding in the subdural space), are not considered as a "hemorrhagic stroke". A hemorrhagic stroke may occur on the background of alterations to the blood vessels in the brain, such as cerebral amyloid angiopathy, cerebral arteriovenous malformation and an intracranial aneurysm, which can cause an intraparenchymal or subarachnoid hemorrhage. In addition to neurological impairment, a hemorrhagic stroke usually causes specific symptoms (for instance, subarachnoid hemorrhage classically causes a severe headache known as a thunderclap headache) or reveal evidence of a previous head injury. ==Signs and symptoms== ===Early recognition=== infographic describing the FAST mnemonic for early recognition of a stroke Systems have been proposed to increase recognition of a stroke. Sudden-onset face weakness, arm drift (i.e., if a person, when asked to raise both arms, involuntarily lets one arm drift downward) and abnormal speech are the findings most likely to lead to the correct identification of a stroke, increasing the likelihood by 5.5 when at least one of these is present. Similarly, when all three of these are absent, the likelihood of a stroke is decreased (– likelihood ratio of 0.39). While these findings are not perfect for diagnosing a stroke, the fact that they can be evaluated relatively rapidly and easily make them very valuable in the acute setting. A mnemonic to remember the warning signs of stroke is FAST (facial droop, arm weakness, speech difficulty, and time to call emergency services), as advocated by the Department of Health (United Kingdom) and the Stroke Association, the American Stroke Association, and the National Stroke Association (US). FAST is less reliable in the recognition of a posterior circulation stroke. The revised mnemonic BE FAST, which adds balance (sudden trouble keeping balance while walking or standing) and eyesight (new onset of blurry or double vision or sudden, painless loss of sight) to the assessment, has been proposed to address this shortcoming and improve the early detection of a stroke even further. Other scales for prehospital detection of stroke include the Los Angeles Prehospital Stroke Screen (LAPSS) and the Cincinnati Prehospital Stroke Scale (CPSS), on which the FAST method was based. Use of these scales is recommended by professional guidelines. For people referred to the emergency room, early recognition of a stroke is important as this can expedite diagnostic tests and treatments. A scoring system called ROSIER (recognition of stroke in the emergency room) is recommended for this purpose; it is based on features from the medical history and physical examination. ===Associated symptoms=== Loss of consciousness, headache, and vomiting usually occur more often in a hemorrhagic stroke than in thrombosis because of the increased intracranial pressure from the leaking blood compressing the brain. If symptoms are maximal at onset, the cause is more likely to be a subarachnoid hemorrhage or an embolic stroke. ===Subtypes=== If the area of the brain affected includes one of the three prominent central nervous system pathways—the spinothalamic tract, corticospinal tract, and the dorsal column–medial lemniscus pathway, symptoms may include: hemiplegia and muscle weakness of the face numbness reduction in sensory or vibratory sensation initial flaccidity (reduced muscle tone), replaced by spasticity (increased muscle tone), excessive reflexes, and obligatory synergies. In most cases, the symptoms affect only one side of the body (unilateral). The defect in the brain is usually on the opposite side of the body. However, since these pathways also travel in the spinal cord and any lesion there can also produce these symptoms, the presence of any one of these symptoms does not necessarily indicate a stroke. In addition to the above central nervous system pathways, the brainstem gives rise to most of the twelve cranial nerves. A brainstem stroke affecting the brainstem and brain, therefore, can produce symptoms relating to deficits in these cranial nerves: altered smell, taste, hearing, or vision (total or partial) drooping of eyelid (ptosis) and weakness of ocular muscles decreased reflexes: gag, swallow, pupil reactivity to light decreased sensation and muscle weakness of the face balance problems and nystagmus altered breathing and heart rate weakness in sternocleidomastoid muscle with inability to turn head to one side weakness in tongue (inability to stick out the tongue or move it from side to side) If the cerebral cortex is involved, the central nervous system pathways can again be affected, but can also produce the following symptoms: aphasia (difficulty with verbal expression, auditory comprehension, reading and writing; Broca's or Wernicke's area typically involved) dysarthria (motor speech disorder resulting from neurological injury) apraxia (altered voluntary movements) visual field defect memory deficits (involvement of temporal lobe) hemineglect (involvement of parietal lobe) disorganized thinking, confusion, hypersexual gestures (with involvement of frontal lobe) lack of insight of his or her, usually stroke-related, disability If the cerebellum is involved, ataxia might be present and this includes: altered walking gait altered movement coordination vertigo and or disequilibrium ===Silent stroke=== A silent stroke is a stroke that does not have any outward symptoms, and people are typically unaware they had experienced a stroke. Despite not causing identifiable symptoms, a silent stroke still damages the brain and places the person at increased risk for both a transient ischemic attack and a major stroke in the future. Conversely, those who have had a major stroke are also at risk of having a silent stroke. In a broad study in 1998, more than 11 million people were estimated to have experienced a stroke in the United States. Approximately 770,000 of these were symptomatic and 11 million were first-ever silent MRI infarcts or hemorrhages. A silent stroke typically causes lesions which are detectable via the use of neuroimaging such as MRI. A silent stroke is estimated to occur at five times the rate of a symptomatic stroke. The risk of a silent stroke increases with age, but may also affect younger adults and children, especially those with acute anemia. ==Causes== ===Thrombotic stroke=== In a thrombotic stroke, a thrombus (blood clot) usually forms around atherosclerotic plaques. Since blockage of the artery is gradual, onset of a symptomatic thrombotic stroke is slower than that of a hemorrhagic stroke. A thrombus itself (even if it does not completely block the blood vessel) can lead to an embolic stroke (see below) if the thrombus breaks off and travels in the bloodstream, at which point it is called an embolus. Two types of thrombosis can cause stroke: Large vessel disease involves the common and internal carotid arteries, the vertebral artery, and the Circle of Willis. Diseases that may form thrombi in the large vessels include (in descending incidence): atherosclerosis, vasoconstriction (tightening of the artery), aortic, carotid or vertebral artery dissection, inflammatory diseases of the blood vessel wall (Takayasu arteritis, giant cell arteritis, vasculitis), noninflammatory vasculopathy, Moyamoya disease and fibromuscular dysplasia. Strokes caused by artery dissections are in the strictest sense not always caused by a 'defined disease state', such events can occur in very young people and can be caused by physical injury such as hyperextension of the neck area or often by other forms of trauma. Small vessel disease involves the smaller arteries inside the brain: branches of the circle of Willis, middle cerebral artery, stem, and arteries arising from the distal vertebral and basilar artery. Diseases that may form thrombi in the small vessels include (in descending incidence): lipohyalinosis (build-up of fatty hyaline matter in the blood vessel as a result of high blood pressure and aging) and fibrinoid degeneration (a stroke involving these vessels is known as a lacunar stroke) and microatheroma (small atherosclerotic plaques). Anemia causes increased blood flow in the blood circulatory system. This causes the endothelial cells of the blood vessels to express adhesion factors which encourages the clotting of blood and formation of thrombus. Sickle-cell anemia, which can cause blood cells to clump up and block blood vessels, can also lead to a stroke. A stroke is the second leading cause of death in people under 20 with sickle-cell anemia. ===Embolic stroke=== An embolic stroke refers to an arterial embolism (a blockage of an artery) by an embolus, a traveling particle or debris in the arterial bloodstream originating from elsewhere. An embolus is most frequently a thrombus, but it can also be a number of other substances including fat (e.g., from bone marrow in a broken bone), air, cancer cells or clumps of bacteria (usually from infectious endocarditis). Because an embolus arises from elsewhere, local therapy solves the problem only temporarily. Thus, the source of the embolus must be identified. Because the embolic blockage is sudden in onset, symptoms are usually maximal at the start. Also, symptoms may be transient as the embolus is partially resorbed and moves to a different location or dissipates altogether. Emboli most commonly arise from the heart (especially in atrial fibrillation) but may originate from elsewhere in the arterial tree. In a paradoxical embolism, a deep vein thrombosis embolizes through an atrial or ventricular septal defect in the heart into the brain. Causes of a stroke related to the heart can be distinguished between high- and low-risk: High risk: atrial fibrillation and paroxysmal atrial fibrillation, rheumatic disease of the mitral or aortic valve disease, artificial heart valves, known cardiac thrombus of the atrium or ventricle, sick sinus syndrome, sustained atrial flutter, recent myocardial infarction, chronic myocardial infarction together with ejection fraction + ) across the cell membrane. However, stroke cuts off the supply of oxygen and glucose which powers the ion pumps maintaining these gradients. As a result, the transmembrane ion gradients run down, and glutamate transporters reverse their direction, releasing glutamate into the extracellular space. Glutamate acts on receptors in nerve cells (especially NMDA receptors), producing an influx of calcium which activates enzymes that digest the cells' proteins, lipids, and nuclear material. Calcium influx can also lead to the failure of mitochondria, which can lead further toward energy depletion and may trigger cell death due to programmed cell death. Ischemia also induces production of oxygen free radicals and other reactive oxygen species. These react with and damage a number of cellular and extracellular elements. Damage to the blood vessel lining or endothelium may occur. These processes are the same for any type of ischemic tissue and are referred to collectively as the ischemic cascade. However, brain tissue is especially vulnerable to ischemia since it has little respiratory reserve and is completely dependent on aerobic metabolism, unlike most other organs. ===Hemorrhagic=== A hemorrhagic stroke is classified based on the underlying pathology. Some causes of hemorrhagic strokes are hypertensive hemorrhage, a ruptured aneurysm, ruptured AV fistula, transformation of prior ischemic infarction, and drug-induced bleeding. They result in tissue injury by causing compression of tissue from an expanding hematoma or hematomas. In addition, the pressure may lead to a loss of blood supply to affected tissue with resulting infarction, and the blood released by brain hemorrhage appears to have direct toxic effects on brain tissue and vasculature. Inflammation contributes to the secondary brain injury after hemorrhage. ==Diagnosis== infarction shown on the left. Right image after 7 hours. A stroke is diagnosed through several techniques: a neurological examination (such as the NIHSS), CT scans (most often without contrast enhancements) or MRI scans, Doppler ultrasound, and arteriography. The diagnosis is clinical, with assistance from the imaging techniques. Imaging techniques also assist in determining the subtypes and cause of a stroke. There is yet no commonly used blood test for the stroke diagnosis itself, though blood tests may be of help in finding out the likely cause. After death, an autopsy may help to establish the time between the stroke onset and death. ===Physical examination=== A physical examination, including taking a medical history of the symptoms and a neurological status, helps to evaluate the location and severity of a stroke. It can give a standard score for example on the NIH stroke scale. ===Imaging=== For diagnosing an ischemic (blockage) stroke in the emergency setting: CT scans (without contrast enhancements) sensitivity= 16% (less than 10% within first 3 hours of symptom onset) specificity= 96% MRI scan sensitivity= 83% specificity= 98% For diagnosing hemorrhagic stroke in the emergency setting: CT scans (without contrast enhancements) sensitivity= 89% specificity= 100% MRI scan sensitivity= 81% specificity= 100% For detecting chronic hemorrhages, an MRI scan is more sensitive. For the assessment of a stable stroke, nuclear medicine scans such as single-photon emission computed tomography (SPECT) and positron emission tomography–computed tomography (PET/CT) may be helpful. SPECT documents cerebral blood flow, whereas PET with an FDG isotope shows cerebral glucose metabolism. CT scans may not detect an ischemic stroke, especially if it is small, of recent onset, or in the brainstem or cerebellum (posterior circulation infarct). MRI is better at detecting a posterior circulation infarct with diffusion-weighted imaging. A CT scan is used more to rule out certain stroke mimics and detect bleeding. The presence of leptomeningeal collateral circulation in the brain is associated with better clinical outcomes after recanalization treatment. Cerebrovascular reserve capacity is another factor that affects the outcome of a stroke it is the amount of increase in cerebral blood flow after a purposeful stimulation of blood flow by the physician, such as by giving inhaled carbon dioxide or intravenous acetazolamide. The increase in blood flow can be measured by PET scan or transcranial doppler sonography. However, in people with obstruction of the internal carotid artery of one side, the presence of leptomeningeal collateral circulation is associated with reduced cerebral reserve capacity. ===Underlying cause=== . ECG changes may occur in people with a stroke and other brain disorders. When a stroke has been diagnosed, other studies may be performed to determine the underlying cause. With the treatment and diagnosis options available, it is of particular importance to determine whether there is a peripheral source of emboli. Test selection may vary since the cause of a stroke varies with age, comorbidity and the clinical presentation. The following are commonly used techniques: an ultrasound/doppler study of the carotid arteries (to detect carotid stenosis) or dissection of the precerebral arteries; an electrocardiogram (ECG) and echocardiogram (to identify arrhythmias and resultant clots in the heart which may spread to the brain vessels through the bloodstream); a Holter monitor study to identify intermittent abnormal heart rhythms; an angiogram of the cerebral vasculature (if a bleed is thought to have originated from an aneurysm or arteriovenous malformation); blood tests to determine if blood cholesterol is high, if there is an abnormal tendency to bleed, and if some rarer processes such as homocystinuria might be involved. For a hemorrhagic stroke, a CT or MRI scan with intravascular contrast may be able to identify abnormalities in the brain arteries (such as aneurysms) or other sources of bleeding, and structural MRI if this shows no cause. If this too does not identify an underlying reason for the bleeding, invasive cerebral angiography could be performed but this requires access to the bloodstream with an intravascular catheter and can cause a further stroke as well as complications at the insertion site and this investigation is therefore reserved for specific situations. If there are symptoms suggesting that the hemorrhage might have occurred as a result of venous thrombosis, CT or MRI venography can be used to examine the cerebral veins. ===Misdiagnosis=== Among people with an ischemic stroke, misdiagnosis occurs 2–26% of the time. A "stroke chameleon" (SC) is a stroke which is diagnosed as something else. People not having a stroke may also be misdiagnosed with the condition. Giving thrombolytics (clot-busting) in such cases causes intracerebral bleeding 1-2% of the time, which is less than that of people with a stroke. This unnecessary treatment adds to health care costs. Even so, the AHA/ASA guidelines state that starting intravenous tPA in possible mimics is preferred to delaying treatment for additional testing. Women, African-Americans, Hispanic-Americans, Asian and Pacific Islanders are more often misdiagnosed for a condition other than a stroke when in fact having a stroke. In addition, adults under 44 years of age are seven times more likely to have a missed stroke than are adults over 75 years of age. This is especially the case for younger people with posterior circulation infarcts. Some medical centers have used hyperacute MRI in experimental studies for people initially thought to have a low likelihood of a stroke, and in some of these people, a stroke has been found which was then treated with thrombolytic medication. ==Prevention== Given the disease burden of a stroke, 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 stroke per year). Recent guidelines detail the evidence for primary prevention in stroke. In healthy people aspirin does not appear beneficial and thus is not recommended as a preventive measure, but in people with high cardiovascular risk, or those who have had a myocardial infarction, it provides some protection against a first stroke. In those who have previously had a stroke, 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 stenosis in those without symptoms. ===Risk factors=== The most important modifiable risk factors for a stroke are chronic uncontrolled hypertension and atrial fibrillation, although the size of the effect is small; 833 people have to be treated for one year to prevent one stroke. 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 an ischemic stroke, as well as intracerebral and subarachnoid hemorrhage via multiple mechanisms (for example, via hypertension, atrial fibrillation, rebound thrombocytosis and platelet aggregation and clotting disturbances). Drug abuse, most commonly involving amphetamines and cocaine, can induce a stroke through damage to the blood vessels in the brain and acute hypertension. Migraine with aura doubles a person's risk for an ischemic stroke. Untreated, celiac disease regardless of the presence of symptoms can be an underlying cause of a stroke, both in children and adults. According to a 2021 WHO study, working 55+ hours a week raises the stroke risk by 35% and the risk of dying from heart conditions by 17%, when compared to a 35–40-hour week. High levels of physical activity reduce stroke risk by about 26%. There is a lack of high quality studies looking at promotional efforts to improve lifestyle factors. Nonetheless, given the large body of circumstantial evidence, best medical management includes advice on diet, exercise, smoking and alcohol use. Medication is the most common method of stroke prevention; carotid endarterectomy can be a useful surgical method of stroke prevention. A 2025 study reported that women under 50 with a history of pregnancy complications face a higher risk of an ischemic stroke. Conditions such as hypertensive disorders of pregnancy, gestational diabetes, preterm birth, small-for-gestational-age infants, stillbirth, and miscarriage were more common among stroke patients than those without. The risk was especially elevated for strokes linked to large artery disease in women with prior hypertensive disorders, preterm births or small-for-gestational-age deliveries. ====Blood pressure==== High blood pressure accounts for 35–50% of stroke risk. Blood pressure reduction of 10 mmHg systolic or 5 mmHg diastolic reduces the risk of stroke by ~40%. Lowering blood pressure has been conclusively shown to prevent both ischemic and hemorrhagic strokes. 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 stroke 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 stroke or TIA has not been shown to result in benefits. ====Blood lipids==== High cholesterol levels have been inconsistently associated with (ischemic) strokes. Statins have been shown to reduce the risk of a stroke by about 15%. Since earlier meta-analyses of other lipid-lowering drugs did not show a decreased risk, statins might exert their effect through mechanisms other than their lipid-lowering effects. ====Diabetes mellitus==== Diabetes mellitus increases the risk of a stroke by about two times, with a more pronounced effect on ischemic than hemorrhagic stroke. 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 a stroke. ====Anticoagulant drugs==== Oral anticoagulants such as warfarin have been the mainstay of stroke prevention for over 50 years. However, several studies have shown that aspirin and other antiplatelets are highly effective in secondary prevention after a stroke 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 stroke 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 stroke prevention after having a myocardial infarction. Those with atrial fibrillation have a 5% a year risk of having a stroke, and those with valvular atrial fibrillation have an even higher risk. Depending on the stroke risk, anticoagulation with medications such as warfarin or aspirin is useful for prevention with various levels of comparative effectiveness depending on the type of treatment used. Oral anticoagulants, especially Xa (apixaban) and thrombin (dabigatran) inhibitors, have been shown to be superior to warfarin in stroke reduction and have a lower or similar bleeding risk in patients with atrial fibrillation. Except in people with atrial fibrillation, oral anticoagulants are not advised for stroke prevention—any benefit is offset by bleeding risk. In primary prevention, however, antiplatelet drugs did not reduce the risk of an ischemic stroke but increased the risk of major bleeding. Further studies are needed to investigate a possible protective effect of aspirin against ischemic strokes 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 stenosis has been shown to be useful in preventing further a stroke in those who have already had the condition. Carotid artery stenting has not been shown to be equally useful. People are selected for surgery based on age, gender, degree of stenosis, time since symptoms and the person's preferences. Surgery is most efficient when not delayed too long—the risk of recurrent stroke in a person who has a 50% or greater stenosis 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 stroke), 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. Studies of surgical intervention for carotid artery stenosis without symptoms have shown only a small decrease in the risk of a stroke. To be beneficial, the complication rate of the surgery should be kept below 4%. Even then, for 100 surgeries, five people will benefit by avoiding stroke, three will develop a stroke despite surgery, three will develop a stroke or die due to the surgery itself, and 89 will remain stroke-free but would also have done so without intervention. ====Diet==== Nutrition, specifically the Mediterranean-style diet, has the potential to decrease the risk of having a stroke by more than half. It does not appear that lowering levels of homocysteine with folic acid affects the risk of a stroke. public service announcement about a woman who had a stroke 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 stroke or TIA=== Keeping blood pressure below 140/90 mmHg is recommended. Anticoagulation can prevent a recurrent ischemic stroke. Among people with nonvalvular atrial fibrillation, anticoagulation can reduce a stroke by 60% while antiplatelets can reduce a stroke by 20%. However, a 2007 meta-analysis suggested harm from anticoagulation started early after an embolic stroke. Stroke prevention treatment for atrial fibrillation is determined according to the CHA2DS2–VASc score. The most widely used anticoagulant to prevent a thromboembolic stroke 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 stroke, should not be stopped for dental procedures. If studies show carotid artery stenosis, and the person has a degree of residual function on the affected side, carotid endarterectomy (surgical removal of the stenosis) may decrease the risk of recurrence if performed rapidly after a stroke. ==Management== Stroke, whether ischemic or hemorrhagic, is an emergency that warrants immediate medical attention. The specific treatment will depend on the type of stroke, the time elapsed since the onset of symptoms, and the underlying cause or presence of comorbidities. ===Ischemic stroke=== Aspirin reduces the overall risk of recurrence by 13% with greater benefit early on. Definitive therapy within the first few hours is aimed at removing the blockage by breaking the clot down (thrombolysis), or by removing it mechanically (thrombectomy). The philosophical premise underlying the importance of rapid stroke intervention was summed up as Time is Brain! in the early 1990s. Years later, that same idea, that rapid cerebral blood flow restoration results in fewer brain cells dying, has been proved and quantified. Tight blood sugar control in the first few hours does not improve outcomes and may cause harm. High blood pressure is also not typically lowered as this has not been found to be helpful. Cerebrolysin, a mixture of pig brain-derived neurotrophic factors used widely to treat acute ischemic stroke in China, Eastern Europe, Russia, post-Soviet countries, and other Asian countries, does not improve outcomes or prevent death and may increase the risk of severe adverse events. There is also no evidence that cerebrolysin‐like peptide mixtures which are extracted from cattle brain is helpful in treating acute ischemic stroke. ====Thrombolysis==== public service announcement on emergency medical treatment after or during stroke from 2021 Thrombolysis, such as with recombinant tissue plasminogen activator (rtPA), in acute ischemic stroke, when given within three hours of symptom onset, results in an overall benefit of 10% with respect to living without disability. It does not, however, improve chances of survival. Benefit is greater the earlier it is used. Between three and four and a half hours the effects are less clear. The AHA/ASA recommend it for certain people in this time frame. A 2014 review found a 5% increase in the number of people living without disability at three to six months; however, there was a 2% increased risk of death in the short term. After four and a half hours thrombolysis worsens outcomes. These benefits or lack of benefits occurred regardless of the age of the person treated. There is no reliable way to determine who will have an intracranial bleed post-treatment versus who will not. In those with findings of savable tissue on medical imaging between 4.5 hours and 9 hours or who wake up with stroke, alteplase results in some benefit. Its use is endorsed by the American Heart Association, the American College of Emergency Physicians and the American Academy of Neurology as the recommended treatment for acute stroke within three hours of onset of symptoms as long as there are no other contraindications (such as abnormal lab values, high blood pressure, or recent surgery). This position for tPA is based upon the findings of two studies by one group of investigators which showed that tPA improves the chances for a good neurological outcome. When administered within the first three hours thrombolysis improves functional outcome without affecting mortality. 6.4% of people with large stroke developed substantial brain bleeding as a complication from being given tPA thus part of the reason for increased short term mortality. The American Academy of Emergency Medicine had previously stated that objective evidence regarding the applicability of tPA for acute ischemic stroke was insufficient. In 2013 the American College of Emergency Medicine refuted this position, acknowledging the body of evidence for the use of tPA in ischemic stroke; but debate continues. Intra-arterial fibrinolysis, where a catheter is passed up an artery into the brain and the medication is injected at the site of thrombosis, has been found to improve outcomes in people with acute ischemic stroke. ====Endovascular treatment==== Mechanical removal of the blood clot causing the ischemic stroke, called mechanical thrombectomy, is a potential treatment for occlusion of a large artery, such as the middle cerebral artery. In 2015, one review demonstrated the safety and efficacy of this procedure if performed within 12 hours of the onset of symptoms. It did not change the risk of death but did reduce disability compared to the use of intravenous thrombolysis, which is generally used in people evaluated for mechanical thrombectomy. Certain cases may benefit from thrombectomy up to 24 hours after the onset of symptoms. ===Hemorrhagic stroke=== People with intracerebral hemorrhage require supportive care, including blood pressure control if required. People are monitored for changes in the level of consciousness, and their blood sugar and oxygenation are kept at optimum levels. Anticoagulants and antithrombotics can make bleeding worse and are generally discontinued (and reversed if possible). Bundled implementation of these supportive measures — including early blood pressure control, glucose and temperature management, and anticoagulation reversal — has been shown to improve functional outcomes in randomised trials and in population-based real-world data. A proportion may benefit from neurosurgical intervention to remove the blood and treat the underlying cause, but this depends on the location and the size of the hemorrhage as well as patient-related factors, and ongoing research is being conducted into the question as to which people with intracerebral hemorrhage may benefit. In subarachnoid hemorrhage, early treatment for underlying cerebral aneurysms may reduce the risk of further hemorrhages. Depending on the site of the aneurysm this may be by surgery that involves opening the skull or endovascularly (through the blood vessels). ===Stroke unit=== Ideally, people who have had stroke are admitted to a "stroke unit", a ward or dedicated area in a hospital staffed by nurses and therapists with experience in stroke treatment. It has been shown that people admitted to stroke units have a higher chance of surviving than those admitted elsewhere in hospital, even if they are being cared for by doctors without experience in stroke. Nursing care is fundamental in maintaining skin care, feeding, hydration, positioning, and monitoring vital signs such as temperature, pulse, and blood pressure. ==Prognosis== Disability affects 75% of stroke survivors enough to decrease their ability to work. Stroke can affect people physically, mentally, emotionally, or a combination of the three. The results of stroke vary widely depending on size and location of the lesion. ==Epidemiology== Stroke was the second most frequent cause of death worldwide in 2011, accounting for 6.2 million deaths (~11% of the total). Approximately 17 million people had stroke in 2010 and 33 million people have previously had stroke and were still alive. Between 1990 and 2010 the incidence of stroke decreased by approximately 10% in the developed world and increased by 10% in the developing world. Overall, two-thirds of stroke occurred in those over 65 years old. South Asians are at particularly high risk of stroke, accounting for 40% of global stroke deaths. Incidence of ischemic stroke is ten times more frequent than haemorrhagic stroke. It is ranked after heart disease and before cancer. In the United States stroke is a leading cause of disability, and recently declined from the third leading to the fourth leading cause of death. Geographic disparities in stroke incidence have been observed, including the existence of a "stroke belt" in the southeastern United States; the pattern has been linked to a higher regional prevalence of traditional risk factors, a larger proportion of Black residents, and lower socioeconomic status, though it is not yet fully explained. The risk of stroke increases exponentially from 30 years of age, and the cause varies by age. Advanced age is one of the most significant stroke risk factors. 95% of stroke occurs in people age 45 and older, and two-thirds of stroke occurs in those over the age of 65. A person's risk of dying with stroke also increases with age. However, stroke can occur at any age, including in childhood. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. Higher levels of Von Willebrand factor are more common amongst people who have had ischemic stroke for the first time. The results of this study found that the only significant genetic factor was the person's blood type. Having stroke in the past greatly increases one's risk of future stroke. Men are 25% more likely to develop stroke than women, yet 60% of deaths from stroke occur in women. Since women live longer, they are older on average when they have stroke and thus more often killed. Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, menopause, and the treatment thereof (HRT). ==History== first described the sudden paralysis that is often associated with stroke. Episodes of stroke and familial stroke have been reported from the 2nd millennium BC onward in ancient Mesopotamia and Persia. Hippocrates (460 to 370 BC) was first to describe the phenomenon of sudden paralysis that is often associated with ischemia. Apoplexy, from the Greek word meaning "struck down with violence", first appeared in Hippocratic writings to describe this phenomenon. The word stroke was used as a synonym for apoplectic seizure as early as 1599, and is a fairly literal translation of the Greek term. The term apoplectic stroke is an archaic, nonspecific term, for a cerebrovascular accident accompanied by haemorrhage or haemorrhagic stroke. Martin Luther was described as having an apoplectic stroke that deprived him of his speech shortly before his death in 1546. In 1658, in his Apoplexia, Johann Jacob Wepfer (1620–1695) identified the cause of hemorrhagic stroke when he suggested that people who had died of apoplexy had bleeding in their brains. Wepfer also identified the main arteries supplying the brain, the vertebral and carotid arteries, and identified the cause of a type of ischemic stroke known as a cerebral infarction when he suggested that apoplexy might be caused by a blockage to those vessels. Rudolf Virchow first described the mechanism of thromboembolism as a major factor. The term cerebrovascular accident was introduced in 1927, reflecting a "growing awareness and acceptance of vascular theories and (...) recognition of the consequences of a sudden disruption in the vascular supply of the brain". Its use is now discouraged by a number of neurology textbooks, reasoning that the connotation of fortuitousness carried by the word accident insufficiently highlights the modifiability of the underlying risk factors. Cerebrovascular insult may be used interchangeably. The term brain attack was introduced for use to underline the acute nature of stroke according to the American Stroke Association, which has used the term since 1990, and is used colloquially to refer to both ischemic as well as hemorrhagic stroke. ==Research== As of 2017, angioplasty and stents were under preliminary clinical research to determine the possible therapeutic advantages of these procedures in comparison to therapy with statins, antithrombotics, or antihypertensive drugs. A 2014 Cochrane review found insufficient evidence to support the use of hyperbaric oxygen therapy in acute ischemic stroke, with no significant reduction in case fatality at six months.

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