3/29/2010

The causes of strokes can be broken down into three main categories: 1) hemorrhage, 2) embolic, 3) thrombotic. Intracerebral hemorrhage occurs when a blood vessel breaks, releasing blood directly into the brain tissue. This can happen from a weakness in the vessel wall, when the blood pressure is too high, or when a person’s blood is not able to clot, for example, when they are placed on “blood thinners.” The resulting blood clot forms a mass and can squeeze surrounding brain, rapidly leading to death or severe brain damage. Often, by the time the patient reaches medical care, it is too late to reverse the damage and many neurosurgeons believe surgery is not worthwhile.

Embolic strokes occur when a blood clot or piece of cholesterol plaque breaks off a heart valve or inside of a blood vessel and flows upstream to becomes lodged in a smaller vessel. This prevents blood from nourishing to the tissue supplied by the vessel. The size of the stroke depends upon where along the vessel it is blocked. Disease that damages the heart valves or the lining of the heart chambers are common causes for emboli.

Thrombotic strokes occur commonly in the carotid and vertebral arteries that supply the brain. Vessel disease, like arteriolosclerosis can narrow the inside of the vessel, slowing blood like a kink in a hose and eventually resulting in a clot that stops flow entirely. There is a narrow window of time that, if this the cause of the stroke is diagnosed and the proper facilities are available, drugs called “clot busters” may help dissolve the blockage and restore flow.

More hospitals are establishing stroke teams, a group of specialized doctors and nurses who can provide the expertise to diagnose and treat stroke as rapidly as possible.