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What Is A Stroke

Updated on September 2, 2012

Defining Stroke

Stroke is a sudden change in neurologic function caused by a change in cerebral blood flow.

The term "stroke" or "paralytic stroke," has about the same meaning as the medical word apoplexy-"to cripple by a stroke." All these terms express the blow like suddenness of symptoms. However there is a great range of manifestations, from so called "little strokes" which may cause a few minutes of confusion, passing dizziness, or slurring of speech, to major strokes which may be quickly fatal.

A medical term that better describes the mechanisms of strokes is cerebral vascular disease, since the underlying cause is impairment of blood supply to the brain.

Classification of stroke

Carotid arteries supply 80 percent of blood flow to the brain, two percent is supplied through vertebrobasilar system

Strokes involving the carotid arteries r called anterior circulatinsroes They often involve cerebral hemispheres.

Strokes affecting the vertebrobasilar arteries are called posterior circulation strokes


Who May Have A Stroke?

Although the stroke victim is usually middle-aged or older, younger men and women are by no means immune.

Cerebrovascular Accident (CVA, Brain Attack, Stroke

CVA is a condition where neurological deficits occur as a result of decreased blood flow to a localized area of the brain; hypertension, diabetes mellitus, sickle cell disease, substance abuse, and atherosclerosis are risk factors for stroke; onset of stroke may be rapid or gradual.

Etiology

Ischemia followed by cell death is the result of severe and prolonged cerebral blood flow obstruction: resulting deficits predict the location of the stroke; there are four types of brain attacks:

1) Transient Ichemic attack (TIA) is a brief period of neurological deficits that resolve within 24 hours; they are frequently precursors to a permanent CVA; tht causes of TIAs may be inflammatory arterial disorders, sickle cell anemia, atherosclerotic changes in cerebral vessels, thrombosis and emboli.

2) Thrombmbotic CVA is caused by thrombus (blood clot) occluding a cerebral vessel thrombi tend to form on atherosclerotic plaque in the larger arteries while the blood pressure s lower such as during sleep or rest); thrombosis occurs quickly but deficits progress slowly.

3) Embolic CVA is caused by a traveling blood clot; the source of the clot is elsewhere in the body; the CVA has a sudden onset wit immediate symptoms; if the embolus is not absorbed, deficits will be persistent.

4)Hemorrhagic CVA or intracranial hemorrhage occurs when a blood vessel ruptures; this most often occurs in the presence of long-term, poorly controlled hypertension; other factors that may cause a hemorrhagic CVA include a ruptured intracranial aneurysm, embolic CVA, tumors, arteriovenous malformations, anticoagulant therapy, liver disease, and blood disorders; this form of CVA is msot often fatal because of rapidly increasing ICP; onset of symptoms is rapid; loss of consciousness occurs in about half the cases.

Care & Treatment

Decades ago the care and treatment of stroke victims was relatively simple. There was no preventive or curative treatment. All that could be done was to attempt to save the patient's life and reduce the ensuing paralysis as much as possible. Accurate localization of the cause of trouble was relatively unimportant, since there was no definitive treatment.

Great advances in diagnosis and treatment of cardiovascular disease have been extended to include diagnosis and treatment of the patient who has sustained a stroke. One of the major advances has been the introducton of angiography, a method of visualizing, blood vessels. In this technique, arteries supplying blood to a portion of the body or brain are visualized by means of a dye as x-ray films are taken of the affected ares.

Drug Therapy and Rehabilitation

Drug therapy is the most common treatment for CVAs; if it is a thrombotic stroke, medications could include thrombolytics and/or heparin.

It is imperative not to disrupt a clot that has formed following hemorrhagic CVA

Surgery is not usually indicated as a treatment modality

Rehabilitation is crucial to improve deficits.

Lower extremities should be monitored for thrombophlebitis

Antiplatelet agents are used to treat TIAs and previous CVA clients, except hemorrhagic CVAs.

Ischemic and hemorrhagic stroke

There are two major types of stroke- ischemic and hemorrhagic, An ischemic stroke occurs when a blood vessel supplying the brain is blocked. It can be life threatening but rarely leads to death within the first hour. A hemorrhagic stroke occurs when a cerebral artery bursts. It can be fatal at onset.

Ischemic Stroke

account for more than 80 percent of strokes. There are two types of ischemic strokes thrombotic and embolitic.

Thrombotic stroke is the most common cause of stroke

in thrombotic stroke , atherosclerosis of large vessels in the brain causes progressive narrowing and platelet clumping. platelet clumping results in the development of blood clots within the brain aretery itself. When the blood clots re of sufficient size to block blood flow through the artery, the area previoussly supplied by that artery becomes ischemic.

Ischemia occurs because the tissue supplied by the blocked artery does not recieve oxygen and the essential nutrient needed for normal brain function. The patients signs and syptoms depend on the location of the artery affected and the areas of brain ischemia.

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