Stroke is the common name for the injury to the brain that occurs when the flow of blood to brain tissue is interrupted by a clogged or burst artery. Arterial blood carries oxygen and nutrition to the cells of the body. When arteries are unable to carry out this function due to rupture, constriction, or obstruction, the cells nourished by these arteries die. The medical term for stroke is the acronym CVA, or cerebral vascular accident. It is estimated that four of every five families in the United States will be affected by stroke in their lifetime, and it is the top cause of adult disability worldwide. Stroke is ranked third in the leading causes of death in the United States, has left three million Americans permanently disabled, and costs the United States 30 billion dollars each year in terms of health care costs and lost productivity.
The most common type of stroke is classified as ischemic, or occurring because the blood supply to a portion of the brain has been cut off. Ischemic strokes account for approximately 80% of all strokes, and can be further broken down into two subtypes: thrombotic, also called cerebral thrombosis; and embolic, termed cerebral embolism.
Thrombotic strokes are by far the more prevalent, and can be seen in nearly all aging populations worldwide. As people grow older, atherosclerosis, or hardening of the arteries, occurs. This results in a buildup of a waxy cholesterol-laden substance in the arteries, which eventually narrows the interior space, or lumen, of the artery. This arterial narrowing occurs in all parts of the body, including the brain. As the process continues, the occlusion, or shutting off of the artery, eventually becomes complete, so that no blood supply can pass through. Usually the presentation of the symptoms of a thrombotic stroke are much more gradual and less dramatic than that of other strokes due to the slow ongoing process that produces it. Transient ischemic attacks, or TIAs, are one form of thrombotic stroke, and usually the least serious. TIAs represent the blockage of a very small artery or arteriole, or the intermittent or temporary obstruction of a larger artery. This blockage affects only a small portion of brain tissue and does not leave noticeable permanent ill effects. These transient ischemic attacks last only a matter of minutes, but are a forewarning that part of the brain is not receiving its necessary supply of blood, and thus oxygen and nutrition. Thrombotic strokes account for 40-50% of all strokes.
Embolic strokes are more acute and rapid in onset. They take place when the heart's rhythm is changed for a number of different reasons, and blood clot formation occurs. This blood clot can move through the circulatory system until it blocks a blood vessel and stops the blood supply to cells in a specific portion of the body. If it occludes an artery that nourishes heart muscle, it causes myocardial infarction, or heart attack. If it blocks off a vessel that feeds brain tissue, it is termed an embolic stroke. Embolisms account for 25-30% percent of all strokes. Normally these blockages occur in the brain itself when arteries directly feeding portions of brain tissue are blocked by a clot. But occasionally the obstruction is found in the arteries of the neck, especially the carotid artery.
Approximately 20% of cerebral vascular accidents are termed hemorrhagic strokes. Hemorrhagic strokes occur when an artery to the brain has a weakness and balloons outward, producing what is called an aneurysm. Such aneurysms often rupture due to this inflation and thinning of the arterial wall, causing a hemorrhage in the affected portion of the brain.
Both ischemic and hemorrhagic strokes display similar symptoms, depending on which portion of the brain is cut off from its supply of oxygen and nourishment. The brain is divided into left and right hemispheres. These hemispheres are responsible for bodily movement on the opposite side of the body from the brain hemisphere. For example, the left hemisphere of the brain is responsible for both motor control and sensory discrimination for the
right side of the body, just as the right hemisphere is responsible for left body movements and feeling. Deeper brain tissue in the left hemisphere of the brain directs muscle tone and coordination for both the right arm and leg. As the communication and speech centers for the brain are also located in the left hemisphere of the brain, interruption of blood supply to that area can also typically affect the person's ability to speak.
Strokes are always considered a medical emergency, and every minute is important in initiating treatment. With the possible exception of transient ischemic attacks, all other types of stroke are life-threatening events. Stroke is a leading cause of death in all nations of the Western world and the more affluent Asian countries. One-quarter of all strokes are fatal. Cerebral vascular accidents are typically a condition of the elderly, and more often happen to men than women. In the United States, strokes occur in roughly one of every 500 people, and the likelihood of becoming a stroke victim rises sharply as a person ages. The incidence of strokes among people ages 30-60 years is less than 1%. This figure triples by the age of 80 years.
Causes & symptoms
Along with the typical risk factors for heart disease, the most common risk factor for thrombotic stroke is age. Some buildup of material along the inner lumen
of the artery, or atherosclerosis, is a normal part of growing older. Hypertension, or high blood pressure, can result from this buildup, as the heart attempts to pump blood through these narrowed arteries. High blood pressure is one of the foremost causes of stroke. Aside from aging and hypertension, heart disease, obesity, diabetes, smoking, oral contraceptives in women, polycythemia, and a condition called sleep apnea are all risk factors for stroke, as is a diet high in cholesterol or fatty foods.
The risk factors for hemorrhagic stroke are those that can weaken arteries supplying blood to the brain. They include high blood pressure, which can over a period of time cause the ballooning of arteries known as aneurysm, and hereditary malformations that produce defective and weakened veins and arteries. Substance abuse also is a major cause. It has been demonstrated for years that cocaine and stimulants such as amphetamine drugs are culprits, and chronic alcoholism can cause a weakening of blood vessels that also can result in hemorrhagic stroke.
Exactly what triggers the actual ischemic stroke event continues to puzzle clinicians. Researchers refer to these triggers as "short-term risk" vs. "long-term risk" factors. If researchers can help identify the triggers for stroke in those with high risk factors, they might be able to help prevent the stroke from occurring. One 2002 report found that abrupt changes in body position caused by sudden loud noises or other unexpected events might trigger a stroke. These events occurred during a two-hour period before the stroke. As noted previously, the symptoms of stroke observed depend upon the part of the brain that is affected, and how large a portion of brain tissue has been damaged by the CVA. Unconsciousness and even seizures can be initial components of a stroke. Other effects materialize over a time period ranging from minutes to hours, and even, in some rare instances, over several days. Headache (often described as "the worst headache I've ever had" in hemorrhagic stroke); mental confusion; vertigo; vision problems, aphasia, or difficulty speaking and communicating, including slurring of words are major symptoms. Hemiplegia, or weakness or paralysis of one side of the body, is a symptom that is frequently seen. This one-sided weakness is often first noticed in the person's face. Stroke victims often have facial drooping, or slackness of the facial muscles on the affected side, as well as difficulty swallowing. The severity of these symptoms will depend upon the amount of brain tissue that has died and its location in the brain.
Computed tomography (CT) brain scans, angiography, lumbar puncture, and magnetic resonance imaging (MRI) are all used to rule out any other possible causes of the symptoms seen. Other possible causes of these symptoms could be brain tumor, brain abscess, subdural hematoma, encephalitis, and meningitis.
There are many applications of alternative and complementary medicine in the treatment and prevention of stroke. Alternative therapies are also used in rehabilitation of stroke victims. Acupuncture and acupressure are commonly used for stroke patients, as is massage. Movement and meditation programs such as t'ai chi are also helpful. Herbs with antioxidant properties may be prescribed by a practitioner. Many therapies aid in blood pressure control, including meditation, guided imagery, biofeedback and t'ai chi.
Much of the needed care immediately following a stroke will be to prevent damage beyond that which has already occurred. Paralysis requires prevention of contractures or tightening up of paralyzed limbs. This is done through physiotherapy, and may include the use of supportive braces for arms or hands, footboards or wearing sneakers when in bed to prevent foot drop. The severely ill stroke patient will need to be repositioned frequently to prevent complications such as pneumonia and venous or pulmonary embolism.
Because of difficulty in swallowing, the person who has suffered a stroke may need a temporary or permanent feeding tube inserted into the stomach to ensure adequate nutrition. Such tubes can be placed through the nose, into the esophagus, and into the stomach, or gastrically, with a wider-lumen tube surgically implanted into the stomach.
A severe stroke that results in coma or unconsciousness will require medical monitoring and support, including oxygen and even possibly intubation to assure an adequate airway and facilitate breathing. Provision of fluids that the person may not be able to take by mouth due to swallowing difficulties will be necessary, as will possibly the administration of such blood-thinning or clot-dissolving medications as Coumadin or heparin. A five-year clinical trial completed in 1995 and reported by the New England Journal of Medicine showed that stroke patients treated with t-PA, a clot-dissolving medication, within three hours of the stroke were one-third more likely to be left with no permanent residual difficulty. The trauma of the brain caused by stroke may result in edema, or swelling, which may have to be reduced by giving the patient diuretic or steroid medications. Sometimes surgical removal of a clot obstructing an artery is necessary. Hemorrhagic stroke can cause a buildup of pressure on the brain that must be relieved as quickly as possible to prevent further brain damage. In extreme cases, this may require incision through the skull to relieve that pressure.
Studies reported by the National Institute of Neurological Disorders and Stroke report that 25% of people who suffer a stroke recover completely and 20% die within three months after the stroke. Of the remaining 55% percent, 5% will require long-term (nursing home) care, and for the rest — roughly half of all stroke patients — rehabilitative and restorative services will be necessary to regain as much of their former capabilities as possible. It has been estimated that the most common irreversible damage from stroke is the loss of intellectual functions.
Control of blood pressure is the single most important factor in preventing stroke. People should have their blood pressure checked regularly, and if consistently elevated, (diastolic, or lower blood pressure beat above 90 to 100, systolic or top beat above 140 to 150), a physician should be consulted.
The American Heart Association recommends that cigarette smokers break the habit to reduce stroke risk. Current cigarette use can increase risk of cerebral infarction to nearly double, and smoking is associated with other risk factors of stroke. The AHA also recommends that those at risk for stroke avoid secondhand tobacco smoke if possible.
Diet, including reduction of sodium (salt) intake, exercise and weight loss, if overweight, are all non-drug treatments for lowering blood pressure. Other natural remedies include eating artichokes, which lowers the fat content of the blood; garlic, now believed to lower cholesterol and blood pressure as well as to reduce the clotting ability of the blood; and ginkgo, which improves circulation and strengthens arteries and veins. The use of folic acid, lecithin, vitamins B 6 and B12, vitamins C and E are all recommended as supportive measures in reducing blood pressure. Two new Harvard studies found that eating a diet high in fruits and vegetables (particularly leafy green vegetables and cruciferous ones like broccoli, cauliflower, and cabbage) can reduce the risk of ischemic stroke. When fruits and vegetables were not only added to the diet, but replaced meat and trans fats, they further reduced stroke risk.
Avoiding substances that can cause stroke is another preventive measure. A 2002 report revealed that the popular herbal supplement ephedrine can cause stroke, heart attack, and sudden death.
Multiple studies have found that aspirin acts as a blood-thinning or clot-reducing medication when taken in small doses. One baby aspirin tablet per day provides this anticoagulant protection.
If necessary, a physician may also order medication to lower blood pressure. These medications include the following categories of drugs:
- Beta blockers reduce the force and speed of the heartbeat.
- Vasodilators dilate the blood vessels.
- Diuretics reduce the total volume of circulating blood and thus the heart's work by removing fluid from the body.
- Lipid-lowering drugs increase the loss of cholesterol from the body or prevent the conversion of fatty acids to cholesterol. This lowers fat levels in the blood stream.
A preliminary report out of France in 2002 stated that getting a flu shot might reduce risk of stroke. Previous research has also suggested that flu shots might stimulate a response in the immune system that helps reduce inflammation throughout the body. If true, those most likely to benefit would be people age 75 and older.
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