Stroke: The sudden death of some brain cells due to a lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain. A stroke is also called a cerebrovascular accident or, for short, a CVA.
Symptoms of a stroke depend on the area of the brain affected. The most common symptom is weakness or paralysis of one side of the body with partial or complete loss of voluntary movement or sensation in a leg or arm. There can be speech problems and weak face muscles, causing drooling. Numbness or tingling is very common. A stroke involving the base of the brain can affect balance, vision, swallowing, breathing and even unconsciousness.
A stroke is a medical emergency. Anyone suspected of having a stroke should be taken immediately to a medical facility for diagnosis and treatment.
The causes of stroke: An artery to the brain may be blocked by a clot (thrombosis) which typically occurs in a blood vessel that has previously been narrowed due to atherosclerosis ("hardening of the artery"). When a blood clot or a piece of an atherosclerotic plaque (a cholesterol and calcium deposit on the wall of the artery) breaks loose, it can travel through the circulation and lodge in an artery of the brain, plugging it up and stopping the flow of blood; this is referred to as an embolic stroke. A blood clot can form in a chamber of the heart when the heart beats irregularly, as in atrial fibrillation; such clots usually stay attached to the inner lining of the heart but they may break off, travel through the blood stream, form a plug (embolism) in a brain artery to cause a stroke. A cerebral hemorrhage (bleeding in the brain), as from an aneurysm (a widening and weakening) of a blood vessel in the brain, also causes stroke.
The diagnosis of stroke involves a medical history and a physical examination. Tests are done to search for treatable causes of a stroke and help prevent further brain damage. A CAT scan (a special X-ray study) of the brain is often done to show bleeding into the brain; this is treated differently than a stroke caused by lack of blood supply. A CAT scan also can rule out some other conditions that may mimic a stroke. A soundwave of the heart (echocardiogram) may be done to look for a source of blood clots in the heart. Narrowing of the carotid artery (the main artery that supplies blood to each side of the brain) in the neck can be seen with a soundwave test called a carotid ultrasound. Blood tests are done to look for signs of inflammation which can suggest inflamed arteries. Certain blood proteins are tested that can increase the chance of stroke by thickening the blood.
Stroke look-alikes: Just because a person has slurred speech or weakness on one side of the body does not necessarily mean that person has had a stroke. There are many other nervous system disorders that can mimic a stroke including a brain tumor, a subdural hematoma (a collection of blood between the brain and the skull) or a brain abscess (a pool of pus in the brain caused by bacteria or a fungus). Virus in the brain (viral encephalitis) can cause symptoms similar to those of a stroke, as can an overdose of certain medications. Dehydration or an imbalance of sodium, calcium, or glucose can cause neurologic abnormalities similar to a stroke.
Treatment of a stroke: Early use of anticoagulants to minimize blood clotting has value in some patients. Treatment of blood pressure that is too high or too low may be necessary. (Lowering elevated blood pressure into the normal range is no longer recommended during the first few days following a stroke since this may further reduce blood flow through narrowed arteries and make the stroke worse.) The blood sugar glucose in diabetics is often quite high after a stroke; controlling the glucose level may minimize the size of a stroke. Drugs that can dissolve blood clots may be useful in stroke treatment. Oxygen is given as needed. New medications that can help oxygen-starved brain cells survive while circulation is reestablished are being developed.
Rehabilitation: When a patient is no longer acutely ill after a stroke, the aim turns to maximizing the patient's functional abilities. This can be done in an inpatient rehabilitation hospital or in a special area of a general hospital and in a nursing facility. The rehabilitation process can involve speech therapy to relearn talking and swallowing, occupational therapy for regaining dexterity of the arms and hands, physical therapy for improving strength and walking, etc. The goal is for the patient to resume as many of their pre-stroke activities as possible.
Footnote: The term "stroke" reflects the belief among the ancient Greeks and Romans that someone suffering a stroke (or any sudden incapacity) had been struck down by the gods.
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