Cerebral vascular disease
Debilitating strokes depicted on television shows or in movies have severe symptoms. Most strokes, however, are not as dramatic. Often the symptoms are minor and transient and may be ignored or dismissed as unimportant. Over time these silent strokes lead to memory loss and other neurological problems. According to one study, by the time people reach their 70s, one in three has a silent stroke every year (Leary 2001).
Of particular concern to stroke victims is that silent strokes occur frequently, causing neurological damage days or weeks after the initial crisis. A 2001 study found that one fourth of stroke survivors had at least one silent stroke during the 2 years following their initial stroke (Corea et al. 2001).
Ischemic strokes account for 80% of all strokes and occur as either an embolic or thrombotic stroke. Thrombotic strokes represent 52% of all ischemic strokes. Thrombotic strokes are caused by unhealthy blood vessels becoming clogged with a buildup of fatty deposits, calcium, and blood-clotting factors such as fibrinogen and cholesterol. We generally refer to this as atherosclerotic disease. Simplistically, what happens with a thrombotic stroke is that our bodies regard these buildups as multiple, infinitesimal, repeated injuries to the blood vessel wall. Our own bodies react to these injuries, just as they would if we were bleeding from a small wound, and they respond by forming blood clots. Unfortunately, in the case of thrombotic strokes, these blood clots get caught on the plaque on the vessel walls and reduce or stop blood flow to the brain.
Two types of thrombosis can cause a stroke: large vessel thrombosis and small vessel disease. Thrombotic stroke occurs most often in the large arteries, magnifying the impact and devastation of disease. Most large vessel thrombosis is caused by a combination of long-term atherosclerosis followed by rapid blood clot formation. Many thrombotic stroke patients have coronary artery disease, and heart attacks are a frequent cause of death in patients who have suffered this type of brain attack.
The second type of thrombotic stroke is small vessel disease which occurs when blood flow is blocked to a very small arterial vessel. Little is known about the specific causes of small vessel disease, but it is often closely linked to hypertension and is an indicator of atherosclerotic disease.
Low-dose aspirin is the antiplatelet agent of choice for stroke prevention. Doses of 160-325 mg daily administered within 48 hours of stroke onset have been shown to significantly reduce the risk of recurrent stroke during the first 2 weeks and possibly improve outcome at 6 months (CASTCG 1997; IST 1997). The Second European Stroke Prevention Study reported risk reductions for aspirin treatment, when compared with a placebo, to be as high as 27.6% (Sivenius et al. 1999).