Cerebrovascular disease; CVA; Cerebral infarction
A stroke is an interruption of the blood supply to any part of the brain, resulting in damaged brain tissue.
Causes, incidence, and risk factors
Stroke accounts for 1 out of every 15 deaths in the United States. It is the 3rd leading cause of death in most developed countries, and the leading cause of disability in adults. The risk doubles with each decade after age 35.
If the flow of blood in an artery supplying the brain is interrupted for longer than a few seconds, brain cells can die, causing permanent damage. An interruption can be caused by either blood clots or bleeding in the brain.
Most strokes are due to blood clots that block blood flow. Bleeding into the brain occurs if a blood vessel ruptures or there is a significant injury.
A common cause of stroke is atherosclerosis. (See stroke secondary to atherosclerosis.) Fatty deposits and blood platelets collect on the wall of the arteries, forming plaques. Over time, the plaques slowly begin to block the flow of blood. The plaque itself may block the artery enough to cause a stroke.
Often, the plaque causes the blood to flow abnormally, which leads to a blood clot. A clot can stay at the site of narrowing and prevent blood flow to all of the smaller arteries it supplies. (This type of clot, which doesn’t travel, is called a thrombus.) In other cases, the clot can travel and wedge into a smaller vessel. (A clot that travels is called an embolism.)
Strokes caused by embolism are most commonly caused by heart disorders. An embolism may originate in a major blood vessel as it branches off the heart. A clot can also form elsewhere in the body for any number of reasons, and then travel to the brain, causing a stroke.
Arrhythmias of the heart, such as atrial fibrillation, can be associated with this type of stroke and may contribute to clot formation. Other causes of embolic stroke include endocarditis (an infection of the heart valves), or use of a mechanical heart valve. A clot can form on the artificial valve, break off, and travel to the brain. For this reason, those with mechanical heart valves must take blood thinners.
BLEEDING IN THE BRAIN
A second major cause of stroke is bleeding in the brain (Hemorrhagic stroke). This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.
High blood pressure is the number one reason that you might have a stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, High cholesterol, and heart disease.
Certain medications promote clot formation and may increase your chances for a stroke. One example is birth control pills, especially if a woman taking them also smokes and is older than 35.
Women have a risk of stroke during pregnancy and the weeks immediately after pregnancy. Overall, however, more men have strokes than women.
Cocaine use, alcohol abuse, Head injury, and bleeding disorders increase the risk of bleeding into the brain.
- Stroke secondary to carotid dissection (bleeding from the carotid arteries)
- Stroke secondary to carotid stenosis (narrowing of the carotid arteries)
- Stroke secondary to cocaine use
- Stroke secondary to FMD (fibromuscular dysplasia)
- Stroke secondary to syphilis
- Hemorrhagic stroke
- Arteriovenous malformation (AVM)
The symptoms of stroke depend on what part of the brain is damaged. In some cases, a person may not even be aware that he or she has had a stroke.
Usually, a SUDDEN development of one or more of the following indicates a stroke:
- Weakness or paralysis of an arm, leg, side of the face, or any part of the body
- Numbness, tingling, decreased sensation
- Vision changes
- Slurred speech, inability to speak or understand speech, difficulty reading or writing
- Swallowing difficulties or drooling
- Loss of memory
- Vertigo (spinning sensation)
- Loss of balance or coordination
- Personality changes
- Mood changes (depression, apathy)
- Drowsiness, lethargy, or loss of consciousness
- Uncontrollable eye movements or eyelid drooping
If one or more of these symptoms is present for less than 24 hours, it may be a transient ischemic attack (TIA). A TIA is a temporary loss of brain function and a warning sign for a possible future stroke.
Signs and tests
In diagnosing a stroke, knowing how the symptoms developed is important. The symptoms may be severe at the beginning of the stroke, or they may progress or fluctuate for the first day or two (stroke in evolution). Once there is no further deterioration, the stroke is considered completed.
During the exam, your doctor will look for specific neurologic, motor, and sensory deficits. These often correspond closely to the location of the injury in the brain. An examination may show changes in vision or visual fields, abnormal reflexes, abnormal eye movements, muscle weakness, decreased sensation, and other changes. A “bruit” (an abnormal sound heard with the stethoscope) may be heard over the carotid arteries of the neck. There may be signs of atrial fibrillation.
Tests are performed to determine the type, location, and cause of the stroke and to rule out other disorders that may be responsible for the symptoms. These tests include:
- Head CT or head MRI - used to determine if the stroke was caused by bleeding (hemorrhage) or other lesions and to define the location and extent of the stroke.
- ECG (electrocardiogram) - used to diagnose underlying heart disorders.
- Echocardiogram - used if the cause may be an embolus (blood clot) from the heart.
- Carotid duplex (a type of ultrasound) - used if the cause may be carotid artery stenosis (narrowing of the major blood vessels supplying blood to the brain).
- Heart monitor - worn while in the hospital or as an outpatient to determine if a heart arrhythmia (like atrial fibrillation) may be responsible for your stroke.
- Cerebral (head) angiography - may be done so that the doctor can identify the blood vessel responsible for the stroke. Mainly used if suregery is being considered.
- Blood work may be done to exclude immune conditions or abnormal clotting of the blood that can lead to clot formation.
A stroke is a medical emergency. Physicians have begun to call it a “brain attack” to stress that getting treatment immediately can save lives and reduce disability. Treatment varies, depending on the severity and cause of the stroke. For virtually all strokes, hospitalization is required, possibly including intensive care and life support.
The goal is to get the person to the emergency room immediately, determine if he or she is having a bleeding stroke or a stroke from a blood clot, and start therapy - all within 3 hours of when the stroke began.
Thrombolytic medicine, like tPA, breaks up blood clots and can restore blood flow to the damaged area. People who receive this medicine are more likely to have less long-term impairment. However, there are strict criteria for who can receive thrombolytics. The most important is that the person be evaluated and treated by a specialized stroke team within 3 hours of when the symptoms start. If the stroke is caused by bleeding rather than clotting, this treatment can make the damage worse - so care is needed to diagnose the cause before giving treatment.
In other circumstances, blood thinners such as heparin and coumadin are used to treat strokes. Aspirin and other anti-platelet agents may be used as well.
Other medications may be needed to control associated symptoms. Analgesics (pain killers) may be needed to control severe headache. Anti-hypertensive medication may be needed to control high blood pressure.
Nutrients and fluids may be necessary, especially if the person has swallowing difficulties. The nutrients and fluids may be given through an intravenous tube (IV) or a feeding tube in the stomach (gastrostomy tube). Swallowing difficulties may be temporary or permanent.
For Hemorrhagic stroke, surgery is often required to remove pooled blood from the brain and to repair damaged blood vessels.
Life support and coma treatment are performed as needed.
The goal of long-term treatment is to recover as much function as possible and prevent future strokes. Depending on the symptoms, rehabilitation includes speech therapy, occupational therapy, and physical therapy. The recovery time differs from person to person.
Certain therapies, such as repositioning and range-of-motion exercises, are intended to prevent complications related to stroke, like infections and bed sores. People should stay active within their physical limitations. Sometimes, urinary catheterization or bladder/bowel control programs may be necessary to control incontinence.
The person’s safety must be considered. Some people with stroke appear to have no awareness of their surroundings on the affected side. Others show indifference or lack of judgment, which increases the need for safety precautions. For these people, friends and family members should repeatedly reinforce important information, like name, age, date, time, and where they live, to help the person stay oriented.
Caregivers may need to show the person pictures, repeatedly demonstrate how to perform tasks, or use other communication strategies, depending on the type and extent of the language problems.
In-home care, boarding homes, adult day care, or convalescent homes may be required to provide a safe environment, control aggressive or agitated behavior, and meet medical needs.
Behavior modification may be helpful for some people in controlling unacceptable or dangerous behaviors.
Family counseling may help in coping with the changes required for home care. Visiting nurses or aides, volunteer services, homemakers, adult protective services, and other community resources may be helpful.
Legal advice may be appropriate. Advance directives, power of attorney, and other legal actions may make it easier to make ethical decisions regarding the care of a person who has had a stroke.
Carotid endarterectomy (removal of plaque from the carotid arteries) may help prevent new strokes from occurring in people with large blockage in these important blood vessels.
Additional support and resources are available from the American Stroke Association. The toll-free phone line for stroke survivors and caregivers is 1-888-4STROKE.
The long-term outcome from a stroke depends on the extent of damage to the brain, the presence of any associated medical problems, and the likelihood of recurring strokes.
Of those who survive a stroke, many have long-term disabilities, but about 10% of those who have had a stroke recover most or all function. Fifty percent are able to be at home with medical assistance while 40% become residents of a long-term care facility like a nursing home.
- Problems due to loss of mobility (joint contractures, pressure sores)
- Permanent loss of movement or sensation of a part of the body
- Bone fractures
- Muscle spasticity
- Permanent loss of brain functions
- Reduced communication or social interaction
- Reduced ability to function or care for self
- Decreased life span
- Side effects of medications
Calling your health care provider
Call your local emergency number (such as 911) if someone has symptoms of a stroke. Stroke requires immediate treatment!
To help prevent a stroke:
- Get screened for high blood pressure at least every two years, especially if you have a family history of high blood pressure.
- Have your cholesterol checked.
- Treat high blood pressure, diabetes, High cholesterol, and heart disease if present.
- Follow a low-fat diet.
- Quit smoking.
- Exercise regularly.
- Lose weight if you are overweight.
- Avoid excessive alcohol use (no more than 1 to 2 drinks per day).
If you have had a TIA or stroke in the past, or you currently have a heart arrhythmia (like atrial fibrillation), mechanical heart valve, congestive heart failure, or risk factors for stroke, your doctor may have you take aspirin or other blood thinners. Make sure you follow your doctor’s instructions and take the medication.
To prevent bleeding strokes, take steps to avoid falls and injuries.
by Sharon M. Smith, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.