Stroke, or sometimes called “brain attack”, occurs when a certain area of the brain suffers from a damaging interruption in normal blood flow. You may have heard of people losing the ability to move one side of the body, losing control over their bladders or bowels, or having trouble speaking as a result of suffering from a major stroke. But how does one get a stroke? What are the medical conditions that contribute to the occurrence of stroke and what are the events that unfold in this disease process?
A stroke may occur in one of two ways, both involving the blood vessels that deliver oxygen and nourishment to the brain tissues. The first and more common of the two involve a blockage of these blood vessels either through a lodged blood clot or an excessive buildup of fat and cholesterol in the blood vessel lining. In these cases, the stroke is termed as ischemic, from the word ischemia which means insufficient blood supply. The blockage is the cause of this insufficient blood supply, as the clot plugs the narrow blood vessels of the brain and decreases or prevents blood from nourishing the brain cells that these arteries normally supply.
The second way through which a stroke may occur is when a blood vessel in the brain ruptures, causing blood to leak and flood the surrounding brain tissues and resulting to injury from the added pressure. This type of stroke is known as hemorrhagic, from the word hemorrhage which means bleeding. Aside from injury as a result of localized pressure, the bursting of a blood vessel in the brain also causes a disruption in the connecting pathways that serve to circulate blood in the entire brain. The factors that may lead to the rupturing of a blood vessel include thin or weak blood vessel walls and excessively high blood pressure.
In both ischemic and hemorrhagic stroke, a disturbance in the normal blood supply affects a certain area of the brain, and oxygen and nutrients do not reach these areas. Because brain cells are not capable of anaerobic metabolism, or metabolism that does not require oxygen, they have an especially short survival time when blood supply is cut off. After 4-6 minutes without sufficient blood supply, brain cells start to die and damaging biochemical substances are released, further adding to brain tissue destruction. As dead brain cells can no longer be replaced, stroke is characterized by a loss of function in the body parts and processes controlled by the damaged area in the brain.
What makes people susceptible to stroke? The contributing factors may either be non-modifiable or modifiable. The non-modifiable factors include such aspects as old age, male sex, family history of stroke, previous heart attack, and African-American, Asian-Pacific, or Hispanic ethnic backgrounds. The modifiable factors include high cholesterol levels in the blood, as cholesterol and fat buildup in blood vessel walls contribute to the risk of ischemic stroke. High blood pressure is another modifiable factor in stroke, as it increases the risk for both hemorrhagic and ischemic stroke. Other modifiable factors include smoking, diabetes, and excessive alcohol intake. If you recognize that you have any of these risk factors for stroke, it would be best to start making positive lifestyle changes now, and consult with a health practitioner for preventive measures against stroke.
