What are the risk factors for stroke?

Overall, the most common risk factors for stroke are:

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

Heart rhythm disturbances like atrial fibrillation, patent foramen ovale, and heart valve disease can also be the cause.

When strokes occur in younger individuals (less than 50 years old), less common risk factors are considered including illicit drugs, such as cocaine or amphetamines, ruptured aneurysms, and inherited (genetic) predispositions to 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.

What is a transient ischemic attack (TIA)?

A transient ischemic attack (TIA) is a short-lived episode (less than 24 hours) of temporary impairment to the brain 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). A spasm and, rarely, a bleed 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 and function will return.

A TIA from a clot to the eye can cause temporary visual loss (amaurosis fugax), which is often described as the sensation of a 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 paralysis of the arm, leg, and face, all on one side. Double vision, dizziness (vertigo), and loss of speech, understanding, and balance can also be symptoms depending on what part of the brain is lacking blood supply.

http://www.medicinenet.com/stroke/page2.htm