Strokes ( Cerebrovascular Accidents )
Stroke affects over 550,000 Americans each year. A stroke occurs in someone every minute of every day. It is the number one cause of disability in the United States. Stroke costs us $30 billion annually in health care costs and lost productivity annually and the average cost per patient for the first 90 days is $15,000. By this metric the cost of a $169 MRI brain scan is modest, indeed. Many strokes are preventable if their causes can be discovered early. There are two major types of stroke:
The brain consists of trillions of nerve cells. In addition, there are trillions of supporting cells necessary to make the nerve cells work. Neurologic functions such as moving, talking, feeling, seeing, thinking, memory, etc. are each carried in specific areas of the brain. The nerve cells in these areas control parts of the body which actually make these functions happen.
The nerve cells and the supporting cells consume a tremendous amount of energy by metabolizing glucose. The metabolic process needs oxygen to work efficiently. Oxygen and glucose is delivered to nerve cells and supporting cells by the blood vessels.
A blockage of a blood vessel in the brain results in death of the cells in the area supplied by that blood vessel. Dead nerve cells perform no functions and the parts of the body controlled by them stop working. So we have paralysis if there is a blockage of the artery supplying the motor area of the brain, partial blindness if there is a blockage of the artery supplying the visual area of the brain and so forth. Most strokes result from atherosclerosis; popularly known as hardening of the arteries. Atherosclerosis can affect arteries anywhere in the body but seems to affect arteries where there is high flow of blood - like the brain. Throughout life, many people have cholesterol and fatty substances deposited in the walls of their arteries. This narrows the diameter of the artery and reduces the flow of blood to whatever that artery supplies - like the brain, for example.
Occasionally, some of those cholesterol and fatty deposits break off and get pushed downstream only to lodge where the artery narrows or branches. This stops the flow of blood to brain tissue fed by that vessel. The brain tissue dies and the person has what is called a stroke.
Blood clots can also form on the cholesterol and fatty deposits in large blood vessels. The blood clots can also dislodge and be pushed downstream and clog a blood vessel. The same thin happens here: the brain tissue fed by this blood vessel dies. If it is important brain tissue, the person will have a noticeable loss of neurologic function. Like paralysis, partial blindness, inability to speak, coma or death - depending on which blood vessel has been occluded.
Early warning signs:
Many stokes do not happen "out of the blue". Many have warning signs: a loss of vision in one eye which gets better after a few minutes or hours, a loss of feeling on one side of the face and arm or temporary weakness of one arm or leg. These evens are called Transient Ischemic Attacks (TIAs).
In addition, "silent strokes" do occur before the "big one" hits. Small emboli of cholesterol or blood clots can clog vessels which feed silent brain tissue. These produce no symptoms. The only way to detect them is their characteristic appearance on an MRI brain scan.
Why must we detect potential strokes early.
Early detection of cholesterol, fatty build-up and clots in the carotid artery - the major artery located in the neck which supplies most of the brain allows early treatment: a simple surgery, a non-invasive endovascular procedure or simple blood thinning therapy.
Early treatment can prevent a devastating stroke later on. After a stroke occurs, the brain tissue supplied by that blood vessel is usually gone forever - and you won't get new brain cells. When they're - they're gone and you are a cripple for the rest of your life.
Therefore, what's the harm of getting a brain scan to see if there is evidence of small silent strokes? For a nominal extra charge the radiologist can also scan the carotid arteries in your neck and detect any problems there as well. If any problem is detected - get it treated before it's too late. Of course, if you want to spend the next three months in a stroke rehabilitation center; that's up to you. But you'll never be the same. God has given you only a certain number of nerve cells. You don't get new ones. When they're gone, they're gone forever.
If you survive the acute event, the recovery from a hemorrhagic stroke is better than from an ischemic stroke. Bleeding into the brain separates brain tissue as a blood clot is formed. Some of this brain tissue may recover after the blood clot is removed surgically or absorbs naturally.
Bleeding into the brain is caused by high blood pressure or weaknesses in the walls of blood vessels. You could be born with these blood vessel defects or they could be the result of trauma or disease. At any rate, blood pours into the brain from the ruptured blood vessels. This can result in no symptoms, in some cases or paralysis, coma and death in severe cases.
Minor hemorrhages may cause no symptoms. However, they will happen again and again until a major hemorrhage occurs which will threaten your neurological function and your life.
Evidence of minor hemorrhages is apparent on MRI. In addition, potential sources for bleeding can also be detected. Things such as aneurysms, AVMs and cavernomas are usually detected on MRI brain sans. An MRI can also detect other blood vessel diseases which could result in hemorrhage into the brain and a hemorrhagic stroke.