Cerebrovascular Accident

stroke

 or cerebrovascular accident (CVA)

Sudden impairment of brain function due to hypoxia, which may cause death of brain tissue. Hypertension, atherosclerosis, smoking, high cholesterol, diabetes, old age, atrial fibrillation, and genetic defects are risk factors. Strokes due to thrombosis (the most common cause), embolism, or arterial spasm, which cause ischemia (reduced blood supply), must be distinguished from those due to hemorrhage (bleeding), which are usually severe and often fatal. Depending on its site in the brain, a stroke's effects may include aphasia, ataxia, local paralysis, and/or disorders of one or more senses. A massive stroke can produce one-sided paralysis, inability to speak, coma, or death within hours or days. Anticoagulants can arrest strokes caused by clots but worsen those caused by bleeding. If the cause is closure of the major artery to the brain, surgery may clear or bypass the obstruction. Rehabilitation and speech therapy should begin within two days to retain and restore as much function as possible, since survivors may live many more years. Transient ischemic attacks (“mini strokes”), with short-term loss of function, result from blockage of blood flow to small areas. They tend to recur and may worsen, leading to multi-infarct dementia or stroke.

---

cerebrovascular accident [sa¦rē·brō′vas·kyə·lər ′ak·sə·dənt]

(medicine)

A symptom complex resulting from cerebral hemorrhage, embolism, or thrombosis of the cerebral vessels, characterized by sudden loss of consciousness.

---

Cerebrovascular Accident 

(or stroke), a disturbance of the cerebral blood circulation that develops acutely and results in injury to brain tissue and impairment of the brain’s functions. Hypertension and atherosclerosis or a combination of the two are the most common causes of a cerebrovascular accident (CVA). It often develops with heart disease, rheumatism, blood diseases, and other ailments. Cerebral hemorrhage is distinguished from ischemic CVA. The former is caused by rupture of the blood vessel and generally occurs in hypertension. Emotional or physical stress often triggers cerebral hemorrhage. This extravasated blood partially destroys and partially compresses the surrounding nerve tissue, causing brain edema. A hemorrhage usually results in serious systematic phenomena—unconsciousness, respiratory and cardiac disturbances, and vomiting. The patient’s face often turns purplish-red. Different kinds of convulsions may occur. Various symptoms of focal brain lesions appear, for example, paralysis of the extremities, disturbance of sensation (or sensory functions), and speech disorders.

A malacia of brain tissue—cerebral infarction—is the basis of ischemic CVA. Cerebral infarction develops after the cerebral blood vessels are occluded by an atherosclerotic plaque, thrombus (blood clot), or embolus (piece of a thrombus or atherosclerotic plaque carried by the blood flow from an unhealthy heart or large blood vessel). Cerebral infarction may also occur after occlusion of the blood flow to some part of the brain owing to blood vessel narrowing by the atherosclerotic process or by a spasm. The brain tissue in the affected zone ceases to receive the oxygen and the nutrients transported by the blood and, as a result, dies and softens. In many cases, atherosclerosis of the major cerebral blood vessels or vessels passing through the neck (carotid and vertebral arteries) as well as neurogenic and metabolic factors play an important role in the ischemic CVA.

The development of an ischemic insult is encouraged by heart failure, a drop in arterial blood pressure, and an increase in blood coagulability. It is often preceded by transient disturbances of the cerebral blood supply manifested by brief numbness in various parts of the body, weakness of the limbs, speech disorders, dizziness, or other disorders. The patient’s face becomes pale. Paralysis, impairment of sensory functions and speech, and other symptoms often progress gradually (in a cerebral hemorrhage they usually set in unexpectedly and suddenly). Only in very critical cases is consciousness lost. Sometimes an examination of cerebrospinal fluid and blood and X-ray studies of the cerebral vessels using contrast substances (angiography) are necessary to make the correct diagnosis and choose the appropriate treatment.

Treatment consists in complete rest and measures to correct the cardiovascular disturbance, prevent or correct respiratory distress, improve the blood supply to the brain, and control brain edema. The choice of method depends on the type of CVA. Surgical methods are being developed to treat cerebral hemorrhage and eliminate the spasm and occlusion of the blood vessels that result in ischemia (when the major cerebral vessels are affected). Therapeutic exercises, massages, practice with a logopedist, and other measures are prescribed for the sequelae of insults. Prophylaxis involves proper work, rest, and eating habits; elimination of mental stress; and treatment of systemic vascular disease.

REFERENCES

Lur’e, Z. L. Rasstroistva mozgovogo krovoobrashcheniia, 2nd ed. Moscow, 1959.
Bogolepov, N. K. “Sosudistye zabolevaniia nervnoi sistemy.” In Mnogo-tomnoe rukovodstvo po nevrologii, vol. 4, part 1. Moscow, 1963.
Shmidt, E. V. Stenoz i tromboz sonnykh arlerii i narusheniia mozgovogo krovoobrashcheniia.Moscow, 1963.
Narusheniia mozgovogo krovoobrashcheniia i ikh khirurgicheskoe leche-nie.Moscow, 1967.

D. K. LUNEV