Stroke (Cerebrovascular Accident)

A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke) or by hemorrhage (a hemorrhagic stroke). The latter occur when a blood vessel in the brain bursts, spilling blood into the spaces surrounding the brain cells or when a cerebral aneurysm ruptures.

Strokes cause loss of brain function in the affected area. A stroke is a medical emergency.

The ischemic stroke is usually caused by atherosclerosis (hardening) of blood vessels, embolus (a piece of blood clot originating from atherosclerotic plaque or heart) or small artery disease (the occlusion of small cerebral vessels by the influence of such presumed factors as diabetes mellitus, elevated blood lipid levels, hypertension and cigarette smoking).

The symptoms of stroke are usually easy to spot: sudden numbness or weakness, especially on one side of the body; sudden confusion or trouble speaking or understanding speech; sudden trouble seeing in one or both eyes; sudden trouble walking; dizziness; or loss of balance or coordination. Despite this, it is possible for someone to have a minor stroke and discover it anywhere from hours to years later.

Brain cells die when they no longer receive oxygen and nutrients from the blood or when they are damaged by sudden bleeding into or around the brain. These damaged cells can linger in a compromised state for several hours. With timely treatment, these cells can be saved.

Stroke is diagnosed through several techniques: a short neurological examination, blood tests, CT scans, MRI scans, Doppler ultrasound, and arteriography. Stroke seems to run in some families. Family members may have a genetic tendency for stroke or share a lifestyle that contributes to stroke. The most important risk factors for stroke are hypertension, heart disease, diabetes, and cigarette smoking. Other risks include heavy alcohol consumption, high blood cholesterol levels, illicit drug use, and genetic or congenital conditions. Some risk factors for stroke apply only to women. Primary among these are pregnancy, childbirth, and menopause.

Treatment
Generally, there are three treatment stages for stroke: prevention, therapy immediately after stroke, and post-stroke rehabilitation. Therapies to prevent stroke are based on treating underlying risk factors. Acute stroke therapies try to stop a stroke while it is happening. Post-stroke rehabilitation is to overcome disabilities that result from stroke damage. Medication or drug therapy is the most common treatment for stroke. Surgery can be used to prevent stroke, to treat acute stroke, or to repair vascular damage or malformations in and around the brain. For most stroke patients, physical therapy is the cornerstone of the rehabilitation process. Another type of therapy involving relearning daily activities is occupational therapy (OT). OT also involves exercise and training to help the stroke patient relearn everyday activities such as eating, drinking and swallowing, dressing, bathing, cooking, reading and writing, and toileting. Speech therapy is appropriate for patients who have no deficits in cognition or thinking, but have problems understanding speech or written words, or problems forming speech.

Prognosis
Although stroke is a disease of the brain, it can affect the entire body. Some of the disabilities that can result from stroke include paralysis, cognitive deficits, speech problems, emotional difficulties, daily living problems, and pain. If the stroke is severe enough, coma or death can result.

Research
Some brain damage that results from stroke may be secondary to the initial death of brain cells caused by the lack of blood flow to the brain tissue. This brain damage is a result of a toxic reaction to the primary damage. Researchers are studying the mechanisms of this toxic reaction and ways to prevent this secondary injury to the brain. Scientists hope to develop neuroprotective agents to prevent this damage. Another area of research involves experiments with vasodilators, medications that expand or dilate blood vessels and thus increase the blood flow to the brain. Basic research has also focused on the genetics of stroke and stroke risk factors. One area of research involving genetics is gene therapy. One promising area of stroke animal research involves hibernation. The dramatic decrease of blood flow to the brain in hibernating animals is extensive enough t that it would kill a non-hibernating animal. If scientists can discover how animals hibernate without experiences brain damage, then maybe they can discover ways to stop the brain damage associated with decreased blood flow in stroke patients. Other studies are looking at the role of hypothermia, or decreased body temperature, on metabolism and neuroprotection. Scientists are working to develop new and better ways to help the brain repair itself and restore important functions to the stroke patients. Some evidence suggests that transcranial magnetic stimulation (TMS), in which a small magnetic current is delivered to an area of the brain, may possibly increase brain plasticity and speed up recover of function after stroke.

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