Stroke, damage to the brain due either to blockage in blood flow or to loss of blood from blood vessels in the brain. Without oxygen and nutrients from blood in the circulatory system, sections of brain tissue quickly deteriorate or die, resulting in paralysis of limbs or organs controlled by the affected brain area. Most strokes are associated with arteriosclerosis (thickening and hardening of arterial walls), or high blood pressure, or both. Some of the signs of major stroke are facial weakness, inability to talk, loss of bladder control, difficulty in breathing and swallowing, and paralysis or weakness, particularly on one side of the body.
Stroke is also called cerebral apoplexy and cerebro vascular accident (CVA).
The majority of stroke cases are due to arterial blockage caused by either thrombosis or embolism. The process that leads to thrombosis begins when fatty substances, or arteriosclerotic plaque, gradually build up in one or more of the four arteries leading to the brain. As these arteries become narrowed, a potential stroke victim often experiences recurrent warnings of transient paralysis, such as in one arm or leg or on one side of the face, or discovers impairments in speech, vision, or other motor functions. At this stage, deposits in the linings of the cerebral arteries can often be treated by surgery, including laser surgery and microsurgical bypass of blockages. Anticoagulant drugs, changes in diet, and even daily doses of aspirin are also used. Actual thrombosis occurs when arteriosclerotic plaque eventually causes an artery to become fully and permanently closed, leading to brain damage.
Embolism occurs when a cerebral artery suddenly becomes blocked by material coming from another part of the bloodstream. Such solid masses, or emboli, often form as clots in a diseased or malfunctioning heart, but can also come from dislodged fragments of arteriosclerotic plaque or even result from an air bubble in the bloodstream. Treatment is largely preventive, consisting of monitoring of the diet, and, if possible, the use of anticoagulant drugs.
Hemorrhaging of cerebral blood vessels, a less frequent cause of stroke, occurs most often where aneurysms, or blister-like bulges, develop on the forks of large cerebral arteries on the brain surface. The brain damage caused by the rupture of aneurysms is due to the seeping of unchanneled blood into brain tissues, or to a reduced flow of blood to the brain beyond the point of rupture, or both.
Rehabilitation from stroke requires specialized help from neurologists, physical therapists, speech therapists, and other medical persons - especially during the first six months, when most progress is made.
Passive stretching exercises and thermal applications are used to regain motor control of limbs, which become rigidly flexed after stroke has occurred. A patient may recover enough to do pulley and bicycle exercises for the arms and legs and, through speech therapy, may regain the language abilities often lost following a stroke; the degree of recovery varies greatly from patient to patient. The death rate among stroke victims in the U.S. has dropped noticeably since 1950. In part this decline may be due to the increasing recognition of the leading role of hypertension in stroke, with resulting dietary changes such as lower intake of saturated fats and cholesterol. Increased awareness of the dangers of smoking may also be a factor. Nevertheless, stroke remains the third leading cause of death in the U.S., following coronary artery disease and cancer. About 731,000 Americans suffer new strokes each year, and in about 154,000 persons the strokes prove fatal.
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