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Stroke SpreadStroke; Are You at Risk?

ABILITY’s Chet Cooper speaks with Dr. Lawrence Goldstein about the Risk factors for a stroke.

CC: Dr. Goldstein, what is a stroke?

LG: A stroke is neurologic deficit caused by damage to an area of the brain. Most commonly, the brain is injured when a plaque (that is in an artery that leads to the brain) breaks off (embolizes) and wedges itself deep into the brain substance. There are over 500,000 strokes per year in the United States. Most of them come from a plaque in the carotid arteries. Less commonly, they come from a blood clot that originates in the heart. Some strokes are caused by hypertension and other reasons, but for the purposes of this interview, we’ll restrict our discussion to carotid arterial disease as it is the most common and treatable cause. Plaque or blood clots travel to the brain, and they result in an area of the brain that does not receive sufficient quantities of oxygen and blood and that area dies. The medical term for this is called an infarction. Whatever area of the brain that is infarcted becomes nonfunctional. Most commonly, strokes affect the motor strength of the arms or legs but can involve the face, or sensation in those areas. Speech and speech recognition and eyesight are common manifestations as well. Since the brain controls the entire body, other complex deficits are also possible.

CC: What is plaque?

LG: Plaque is a layman’s term for atherosclerosis. Another common term to describe plaque is hardening of the arteries. Nobody really knows what causes atherosclerosis, but even children can have some signs of atherosclerosis and by the time they become adults, hardening can become significant. There are risk factors for developing atherosclerosis, some of which you have control over, and some of which you don’t. For instance, being a man is a risk factor for having a stroke. Genetics or family inheritance is another risk factor. Both of these we have no control over. However, high blood pressure and diabetes are risk factors that can be treated. Blood levels high in cholesterol and certain types of fat are risk factors as well. So, some of these risk factors you can modify, and some are fixed risks.

CC: Is the risk for men higher than for women?

LG: Yes. However, after menopause, women are less protected, which is felt to be due to the loss of the hormonal influence of estrogen.

Brain DiagramCC: Is age a risk factor?

LG: Age is another risk factor. As I have mentioned, even children can have some evidence of atherosclerosis, but as we age, there is a higher likelihood that the plaque will become significant and cause an obstruction or embolism.

CC: Are there early symptoms?

LG: Unfortunately, most patients’ first presentation of a stroke is the stroke itself. However, approximately 20% of patients have warning signs and symptoms. One common symptom is called amaurosis fugax or “monocular blindness.” Amaurosis fugax is transient blindness in one eye, usually described as appearing as if a window shade is being pulled over the eye. The patient completely loses his vision for a short time, and then the vision returns to normal, usually within minutes, although the episode can last up to twenty-four hours. That is a specific kind of TIA, which is an abbreviation for transient ischemic attack. In this case the ischemic attack affects the retina, or the transducer of light in the eye to images perceived by the brain. Amaurosis fugax occurs because debris primarily from the carotid (neck) arteries embolize to the retinal artery and renders some cells of the retina nonfunctional. The event is transient, probably because the blood clot breaks up and frees the obstruction.

The medical definition of a TIA is a neurologic deficit that lasts less than twenty-four hours, but if it lasts over twenty-four hours but less than three weeks, this is commonly referred to as a reversible ischemic neurologic deficit, or RIND. That is basically the same thing as a TIA but it lasts longer. If the deficit lasts longer than three weeks, it is a true infarction or a permanent stroke.

Another warning sign is weakness or numbness, or even paralysis, of one leg, arm, or both. If the arm and leg are involved simultaneously, it occurs on one side only, which is on the opposite side of the brain that is involved in the ischemic event(s). Ischemia means inadequate blood flow to the brain in this case. When inadequate blood flow is delivered to a portion of the brain, that portion will not function, and it will result in a neurological deficit like numbness of a hand, or weakness of an extremity, or blindness.

CC: How does someone know the difference between numbness and weakness?

LG: Everyone has had numbness and weakness. Anyone who has rested on an arm for prolonged period or has slept with arms over head and they have “fallen asleep” knows what numbness is. In those two instances there is a reason for that arm to be numb, either due to a compressed nerve or diminished blood flow to the arm from positional causes. Numbness caused by brain ischemia feels the same as numbness caused for any reason but is not related to these other mechanisms. This is true of weakness as well. In a weak extremity, one does not have as much strength as before. Sometimes it is subtly weaker but sometimes the limb doesn’t move at all and that is called paralysis. In paralysis, one is unable to lift the arm despite emphatically trying to do so. Some patients are unaware that this is happening because an area of the brain that is concerned with this is involved in the ischemic process as well, and they neglect the affected extremity. These patients may use their other arm to move the affected extremity. In general, paralysis affects one leg or arm, and if it involves both, they will be on the same side. The numbness won’t go away in the same manner as it would after relieving the stress that caused the numbness for mechanical reasons.

CC: What is the time interval between the warning sign and the stroke?

LG: There’s no way to predict the time interval between warning signs and a stroke. Some patients never get a stroke, but the chances of getting one is much higher if you have warning signs and carotid arterial disease compared to the general population. The chances of getting stroke in six months after a transient ischemic episode is in the neighborhood of 10% and in a year it may be up to 20%. In subsequent years the stroke rate is about 6% per year in addition thereafter. One may get another TIA in a month, or six months, or worse, a couple a day. If you have TIA’s often or more frequently, medical attention is crucial. This sign is called crescendo TIA’s. That is an emergency because a subsequent stroke is felt to be much more imminent in this subpopulation. Most people (80%) unfortunately don’t have any warning signs. Patients who have just one ischemic episode often forget about it until a doctor inquires about it, sometimes for unrelated reasons. Those are the people we want to see earlier because we can potentially prevent them from having a major stroke that may kill them.

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More stories from Kirk Douglas issue:

Kirk Douglas Interview

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Adaptive Technologies; Making Computers Accessible

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