Stroke (cont.)

Overall, the most common risk factors for stroke are:

• high blood pressure,
• high cholesterol,
• smoking,
• diabetes, and
• increasing age.

Heart conditions like atrial fibrillation, patent foramen ovale, and heart valve disease can also be the potential cause of stroke.

When stroke occurs in younger individuals (less than 50 years old), less common risk factors to be considered include illicit drugs, such as cocaine or amphetamines, ruptured aneurysms, and inherited (genetic) predispositions to abnormal blood clotting.

An example of a genetic predisposition to stroke occurs in a rare condition called homocystinuria, in which there are excessive levels of the chemical homocystine in the body. Scientists are trying to determine whether the non-hereditary occurrence of high levels of homocystine at any age can predispose to stroke.

A transient ischemic attack (TIA, mini-stroke) is a short-lived stroke that gets better and resolves. It is a short-lived episode (less than 24 hours) of temporary impairment of brain function that is caused by a loss of blood supply. A TIA causes a loss of function in the area of the body that is controlled by the portion of the brain affected. The loss of blood supply to the brain is most often caused by a clot that spontaneously forms in a blood vessel within the brain (thrombosis). However, it can also result from a clot that forms elsewhere in the body, dislodges from that location, and travels to lodge in an artery of the brain (emboli). Arterial spasm and, rarely, a bleed into brain tissue are other causes of a TIA. Many people refer to a TIA as a "mini-stroke."

Some TIAs develop slowly, while others develop rapidly. By definition, all TIAs resolve within 24 hours. Strokes take longer to resolve than TIAs, and with strokes, complete function may never return and reflect a more permanent and serious problem. Although most TIAs often last only a few minutes, all TIAs should be evaluated with the same urgency as a stroke in an effort to prevent recurrences and/or strokes. TIAs can occur once, multiple times, or precede a permanent stroke. A transient ischemic attack should be considered an emergency because there is no guarantee that the situation will resolve itself and function will return spontaneously without the help of medical intervention.

A TIA from a clot in the blood vessel that supplies the retina of the eye can cause temporary visual loss (amaurosis fugax), which is often described as the sensation of a black, dark curtain coming down. A TIA that involves the carotid artery (the largest blood vessel supplying the brain) can produce problems with movement or sensation on one side of the body, which is the side opposite to the actual blockage. An affected patient may experience temporary double vision; dizziness (vertigo); loss of balance; one-sided weakness or complete paralysis of the arm, leg, face or one whole side of the body; or be unable to speak or understand commands.

Source: MedicineNet.com
http://www.medicinenet.com/stroke/article.htm