/strohk/, n., v., stroked, stroking.
1. the act or an instance of striking, as with the fist, a weapon, or a hammer; a blow.
2. a hitting of or upon anything.
3. a striking of a clapper or hammer, as on a bell.
4. the sound produced by this.
5. a throb or pulsation, as of the heart.
6. Also called apoplexy, cerebrovascular accident. Pathol. a blockage or hemorrhage of a blood vessel leading to the brain, causing inadequate oxygen supply and, depending on the extent and location of the abnormality, such symptoms as weakness, paralysis of parts of the body, speech difficulties, and, if severe, loss of consciousness or death.
7. something likened to a blow in its effect, as in causing pain, injury, or death; an attack of apoplexy or paralysis.
8. a destructive discharge of lightning.
9. a vigorous movement, as if in dealing a blow.
10. Sports. a hitting of a ball, as by the swing of a racquet in tennis or the controlled jabbing or thrusting with the cue in pool and billiards.
11. a single complete movement, esp. one continuously repeated in some process.
12. Mach.
a. one of a series of alternating continuous movements of something back and forth over or through the same line.
b. the complete movement of a moving part, esp. a reciprocating part, in one direction.
c. the distance traversed in such a movement.
d. a half revolution of an engine during which the piston travels from one extreme of its range to the other.
13. Swimming.
a. a type or method of swimming: The crawl is a rapid stroke.
b. each of the successive movements of the arms and legs in propelling the body through the water.
14. Rowing.
a. a single pull of the oar.
b. the manner or style of moving the oars.
c. Also called stroke oar. the crew member nearest to the stern of the boat, to whose strokes those of the other crew members must conform.
15. a movement of a pen, pencil, brush, graver, or the like.
16. a mark traced by or as if by one movement of a pen, pencil, brush, or the like.
17. a distinctive or effective touch in a literary composition: His style revealed the stroke of a master.
18. a single or minimal act, piece, or amount of work, activity, etc.: to refuse to do a stroke of work.
19. an attempt to attain some object: a bold stroke for liberty.
20. a measure adopted for a particular purpose.
21. a keystroke: no more than 65 strokes to the line for business letters.
22. a feat or achievement: a stroke of genius.
23. a sudden or chance happening, as of luck or fortune.
24. to mark with a stroke or strokes, as of a pen; cancel, as by a stroke of a pen.
25. Rowing.
a. to row as a stroke oar of (a boat or crew).
b. to set the stroke for the crew of (a boat).
26. Sports. to hit (a ball), as with a deliberate, smooth swing of a bat or club.
[1250-1300; ME strok, strak (n.), prob. continuing OE *strac (whence stracian to STROKE2); c. G Streich; akin to STRIKE]
Syn. 1. rap, tap, knock, pat. 1, 7. See blow1. 5. beat, thump; rhythm.
/strohk/, v., stroked, stroking, n.
1. to pass the hand or an instrument over (something or somebody) lightly or with little pressure; rub gently, as in soothing or caressing.
2. Informal. to promote feelings of self-approval in; flatter.
3. an act or instance of stroking; a stroking movement.
[bef. 900; ME stroken (v.), OE stracian; c. G streichen; akin to STRIKE]

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Sudden impairment of brain function due to hypoxia, which may cause death of brain tissue.

Hypertension, atherosclerosis, smoking, high cholesterol, diabetes, old age, atrial fibrillation, and genetic defects are risk factors. Strokes due to thrombosis (the most common cause), embolism, or arterial spasm, which cause ischemia (reduced blood supply), must be distinguished from those due to hemorrhage (bleeding), which are usually severe and often fatal. Depending on its site in the brain, a stroke's effects may include aphasia, ataxia, local paralysis, and/or disorders of one or more senses. A massive stroke can produce one-sided paralysis, inability to speak, coma, or death within hours or days. Anticoagulants can arrest strokes caused by clots but worsen those caused by bleeding. If the cause is closure of the major artery to the brain, surgery may clear or bypass the obstruction. Rehabilitation and speech therapy should begin within two days to retain and restore as much function as possible, since survivors may live many more years. Transient ischemic attacks ("mini strokes"), with short-term loss of function, result from blockage of blood flow to small areas. They tend to recur and may worsen, leading to multi-infarct dementia or stroke.

* * *

also called  apoplexy 

      sudden impairment of brain function resulting either from a substantial reduction in blood flow to some part of the brain or from intracranial bleeding. The consequences of stroke may include transient or lasting paralysis on one or both sides of the body, difficulties in speaking or eating, and a loss in muscular coordination. A stroke may cause cerebral infarctions (infarction)—dead sections of brain tissue. Smoking, high cholesterol, diabetes (diabetes mellitus), aging, and heritable defects are among the major risk factors of stroke.

      The most common cause of stroke is a blood clot (thrombus) that has formed within a blood vessel of the brain. A blood clot also can lodge in an artery supplying brain tissue after originating in another portion of the body and traveling to the brain. This is known as an embolism. A myocardial infarction ( heart attack), damage to a heart valve, and an irregular heartbeat called atrial fibrillation can cause blood clots that may reach the brain. Both types of clots reduce or stop the flow of blood to brain cells. During the early stages of stroke from a blood clot, the condition may be further complicated by the leakage of blood and fluid into the surrounding areas ( edema).

      Stroke can also occur as a result of atherosclerosis, the buildup of fatty deposits on artery walls. Atherosclerosis can cause intermittent insufficiency in the flow of blood due to spasm of the arteries or the sludging of the blood as it passes through segments of vessels that have been narrowed by fatty deposits.

      A hemorrhagic stroke, involving intracranial bleeding, may occur after an artery ruptures, usually as a result of a weakening of the arterial wall because of atherosclerosis or because of a thinning of the wall along with bulging ( aneurysm), often due to hypertension.

      Transient ischemic attacks, or mini-strokes, result when long, thin arteries penetrating deep into the brain become blocked by atherosclerosis, causing areas of surrounding tissue to lose their blood supply. The tissue may then wither, creating minute holes, called lacunes. A succession of transient ischemic attacks over the years can riddle the brain, causing dementia.

      The initial onset of stroke may be massive in its effects, producing widespread paralysis, inability to speak, coma, or death within a short time, usually within several hours or days. On the other hand, the onset may be manifested by a series of transient ischemic attacks during which the patient may experience weakness and numbness of an arm, a leg, or a side of the face. There may be temporary difficulty in speech, confusion, or visual disturbances. Transient ischemic attacks may recur many times, but they are usually followed eventually by more widespread and permanent paralysis.

      The groups of muscles and nerves involved are a direct reflection of the artery and brain tissues involved. If the left side of the brain (the dominant side for most persons) is affected, there is a paralysis of the right side of the body because most of the nerves cross to the opposite side of the body from their origin in the brain. However, the combinations of signs and symptoms are innumerable.

      Precise history and physical examination, especially for neurological changes, are essential to differentiate stroke from a tumour and from brain injury resulting from other causes. It is also important to determine whether the stroke is due to a thrombus, embolism, or hemorrhage. Examination of the spinal fluid for evidence of blood is often essential. Diagnostic imaging (as by computerized tomography [CT] scan (computerized axial tomography)) may clarify the diagnosis. Establishing a differential diagnosis is essential because anticoagulant drugs are widely used in the treatment of stroke due to thromboses (thrombosis) or emboli but are contraindicated when due to hemorrhage. A stroke may have both a clotting and a significant hemorrhagic factor present, and this presents difficulties. Many strokes are due to closure of one of the two carotid arteries that supply the brain after passing up the sides of the neck from the aorta. If the closure involves only a small segment, surgery may be attempted to remove the obstruction or to insert a graft or synthetic bypass.

      Many persons who have a stroke live for years after the event. Early and persistent efforts for rehabilitation are essential, including both physical, occupational, and speech therapy. These therapies should begin within a day or two after the stroke.

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Universalium. 2010.

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