A stroke, sometimes referred to as a cerebrovascular accident (CVA), cerebrovascular insult (CVI), or colloquially brain attack is the loss of brain function due to a disturbance in the blood supply to the brain.

This disturbance is due to either ischemia (lack of blood flow) or hemorrhage.

Ischemia is caused by either blockage of a blood vessel via thrombosis or arterial embolism, or by systemic hypoperfusion.

Hemorrhagic stroke is caused by bleeding of blood vessels of the brain, either directly into the brain parenchyma or into the subarachnoid space surrounding brain tissue.

As a result, the affected area of the brain cannot function normally, which might result in an inability to move one or more limbs on one side of the body, failure to understand or formulate speech, or a vision impairment of one side of the visual field.

A stroke is a medical emergency and can cause permanent neurological damage or death.

Risk factors for stroke include old age, high blood pressure, previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, tobacco smoking, and atrial fibrillation.

High blood pressure is the most important modifiable risk factor of stroke.

An ischemic stroke is occasionally treated in a hospital with thrombolysis (also known as a “clot buster”), and some hemorrhagic strokes benefit from neurosurgery.

Treatment to recover any lost function is termed stroke rehabilitation, ideally in a stroke unit and involving health professions such as speech and language therapy, physical therapy and occupational therapy.

Prevention of recurrence may involve the administration of antiplatelet drugs such as aspirin and dipyridamole (a synthetic drug used as a coronary vasodilator to treat angina and to reduce platelet aggregation and hence the chance of thrombosis), control and reduction of high blood pressure, and the use of statins (cholesterol medications).

Selected patients may benefit from carotid endarterectomy and the use of anticoagulants.

Classification

Strokes can be classified into two major categories: ischemic and hemorrhagic.

Ischemic strokes are caused by interruption of the blood supply, while hemorrhagic strokes result from the rupture of a blood vessel or an abnormal vascular structure.

About 87% of strokes are ischemic, the rest are hemorrhagic.

Some hemorrhages develop inside areas of ischemia (“hemorrhagic transformation”). It is unknown how many hemorrhagic strokes actually start as ischemic stroke.

Stroke symptoms typically start suddenly, over seconds to minutes, and in most cases do not progress further. The symptoms depend on the area of the brain affected. The more extensive the area of the brain affected the more functions that are likely to be lost.

Some forms of stroke can cause additional symptoms.

For example, in intracranial hemorrhage, the affected area may compress other structures.

Most forms of stroke are not associated with headaches, apart from subarachnoid hemorrhage and cerebral venous thrombosis and occasionally intracerebral hemorrhage.

Various systems have been proposed to increase the recognition of stroke. Different findings are able to predict the presence or absence of stroke to different degrees.

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 case of 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 stroke is significantly decreased.

While these findings are not perfect for diagnosing stroke, the fact that they can be evaluated relatively rapidly and easily make them very valuable in the acute setting.

Proposed systems include FAST (face, arm, speech, and time). The use of these scales is recommended by professional guidelines.

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