Stroke / Cerebrovascular Accident (CVA)

Medical Code: SGM-FS-010
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Condition: Stroke / Cerebrovascular Accident (CVA)

Prevalence: 150,000 cases/year

Layman’s Definition: A sudden interruption in blood flow to part of the brain caused either by a blockage in a blood vessel or a rupture in the blood vessel which prevents blood from reaching downstream sites.  The location of the blood flow interruption will determine the symptoms.  The cause of the interruption will determine the treatment.

Typical Age of Symptom Onset: >50 years

Primary Symptoms:  Sudden loss of function in any area of the body which continues for more than two hours. (Similar symptoms lasting less than two hours may be due to a Transient Ischemic attack [TIA], which is essentially a muscle cramp in the muscle cells surrounding one of the blood vessels in your brain. See Fact Sheet Transient Ischemic Attack.)

The symptoms of a stroke will depend on the size and location of the area of tissue damage (infarct). They may include loss of muscle control, vision, or hearing; an inability to speak; or mental confusion. The effects of a stroke may be as small as a drooping eyelid or sudden difficulty swallowing, or they may cause paralysis on one side of the body or unconsciousness, depending on whether a major blood vessel is involved or only a tiny branch. Due to the way blood vessels in the brain are organized, stroke damage is usually limited to only one side of the body. That is, a stroke on one side of the brain will affect the opposite side of the body.   

Secondary Symptoms: If the stroke is caused by a ruptured cerebral aneurysm, the person usually experiences a sharp sudden headache before the loss of control.

If it’s caused by a blood clot, the person may experience a feeling of weakness in the affected body part prior to the loss of control.

A sudden loss of muscle control on one side of the body may cause the person to fall, possibly causing other injuries.

Due to a trick that brain cells can use to temporarily conserve oxygen after a disruption in their blood supply, an apparently stable stroke patient in the hospital may suddenly get a lot better or a lot worse within two days after the stroke. This is why a sudden worsening of symptoms may not indicate that the person has suffered a second stroke or that something went wrong with their treatment.

Some people who have had a stroke will have epileptic seizures later as a result of the tissue damage.

Cause(s)/Risk Factor(s): The most common cause of a stroke is a blood clot from somewhere else in the body breaking off, traveling to the brain, and blocking blood flow. (This is called a thrombolytic stroke.)

A second, less common type of stroke is caused by blood vessels becoming leaky, like a broken water main down the street that causes your shower to lose water pressure. This second type is called a hemorrhagic stroke and can be caused by too-high levels of the same anti-clotting drugs that some people take to prevent heart attacks or thrombolytic strokes. Hemorrhagic strokes can also be caused by the rupture of a weakened section of an artery in the brain (a ruptured cerebral aneurism, intra cerebral hemorrhage, or subarachnoid hemorrhage). (See Fact Sheet Aneurysm)

Standard Treatment(s): The treatment for a stroke will depend on whether it is caused by a blot clot (thrombolytic stoke) or leakage (hemorrhagic stroke).

Thrombolytic strokes are treated with anticoagulants, which are blood-thinning drugs, in order to break up the clot and restore blood flow. Rapid treatment (within three hours) is generally advised in order to minimize cell death due lack of oxygen and thereby reduce the extent of long-term impairment.

There is no comparable simple treatment for hemorrhagic strokes. In fact, treating a hemorrhagic stroke with anticoagulants is likely to make things worse. Clotting factors or reversing agents for blood thinners may be administered if hemorrhage is thought to be caused by too-high levels of anti-clotting medication. To reduce bleeding, blood pressure may also be lowered. In order to minimize brain damage, surgery is sometimes preformed to open up a portion of the skull and drain excess fluid. If the stroke is due to a ruptured cerebral aneurysm, surgical repair of the blood vessel will generally be recommended as soon as possible if the rupture is small enough to be survivable. (See Fact Sheet: Aneurysm)         

Unfortunately, the cause of a stroke is not always easy to identify, especially if the person was taking anticoagulants for a clotting risk such as an artificial heart valve or stent. X-rays, particularly those taken with computer enhancement (CT scans), can detect localized concentrations of iron in pools of red blood cells caused by relatively large cerebral hemorrhages strokes, but they cannot always detect smaller bleeds. The interrupted blood flow of a thrombolytic stroke can usually be detected with magnetic resonance imaging (MRI), but these images can be difficult to interpret for smaller stokes at early time points.

Blood tests to determine clotting rates can be useful for assessing the relative likelihood of clot formation versus spontaneous bleeding. If the patient is able to talk, or if someone was with them when they had the stroke, symptoms that occurred immediately before the stroke can provide important clues. For example, someone with a thrombolytic stroke usually describes a weakening of the affected part of the body before total loss of control, while someone experiencing a ruptured aneurysm usually reports a sudden sharp headache immediately before losing control or consciousness.

Even when the cause of the stroke is known, treatment may be complicated by other factors, such as injuries occurring as a result of the stroke. If someone who suffered a thrombolytic stroke had a fall or other accident, any internal bleeding would be worsened by the use of clot-busting drugs. Similarly, the body’s attempt to seal off blood vessel leaks after a hemorrhagic stroke may cause clots to form, break off, and lodge in other blood vessels, and/or block the circulation of cerebral spinal fluid. In short, although the diagnosis and treatment of a stroke is sometimes very simple and straightforward, in other cases, the best course of action is uncertain.

Immediately following a stroke, it can be difficult to assess the long-term effects. The brain can have some of its nerve cells go into a sort of hibernation for up to 48 hours, in order conserve resources if the blood supply is interrupted. When these systems wake up again, the person may suddenly regain functions that appeared to have been lost. On the other hand, if normal blood supply has not been restored, more neurons may begin to die as the result of too many cells competing for too small a supply of oxygen and glucose. People who have had a stroke may therefore suddenly start to get better or suddenly take a turn for the worse during this two-day time period. MRIs taken immediately after a stroke can only determine the location and size of the core area of brain damage (the infarct). The fate of the much larger area around this injured zone (the penumbra) will depend on how successful the doctors and the patient’s own body were in quickly restoring normal blood supply.   

Physical therapy, occupational therapy, and/or speech therapy are likely to be recommended in order to begin retraining spared nerve cells to take over the jobs of the cells that have been lost and/or to develop strategies for working around any limitations. The retraining process is likely to take several months.

Low doses of anti-clotting drugs may be prescribed on an ongoing basis after a thrombolytic stroke in order to prevent another stroke, l .

Anti-seizure medication may be prescribed if localized brain injury causes the person to develop seizures.

Counseling or group therapy may be recommended to help the person deal with the emotional aftermath of the brain injury and any lingering disability.

For more information about the causes and symptoms of a stroke, see:  http://www.mayoclinic.org/diseases-conditions/stroke/symptoms-causes/dxc-20117265

For more information about rehabilitation after a stroke, see: https://stroke.nih.gov/materials/rehabilitation.htm

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