Ischemic Stroke

Definition

Stroke is a brain injury caused by an interruption in blood flow. Brain tissue that does not get oxygen and nutrients from blood can die within minutes. The damage to the brain can cause a sudden loss in bodily functions. The types of function that are affected will depend on the part of the brain that is damaged.

There are 2 blood flow problems that cause a stroke. Strokes may be ischemic or hemorrhagic.

• An ischemic stroke is caused by a blocked blood vessel. It is the most common cause of stroke.
• A hemorrhagic stroke is caused by a ruptured blood vessel.

Hemorrhagic vs. Ischemic Stroke

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Causes

Blood flow may be blocked by one or both of the following:

• Buildup or swelling of the walls of the blood vessels
• Something in the blood sticking to blood vessel walls

A blockage in a small blood vessel will affect a smaller area of the brain. A blockage in larger blood vessels will block flow to many smaller blood vessels. This will affect more of the brain.

The blockage may be the result of one or more of the following:

• Atherosclerosis—a build-up of fatty substances along the inner lining of the artery that gradually decrease the area the blood can flow through
• A blood clot that has traveled from other parts of the body, such as the neck or heart
• Swelling (inflammation) of the blood vessels
• A combination of above (example: blood clot gets trapped in blood vessel narrowed by swelling)

Risk Factors

Certain factors increase your risk of stroke but cannot be changed, such as:

• Race—People of African, Hispanic, or Asian/Pacific Islander descent are at increased risk
• Age: Older than 55 years of age
• Family history of stroke

Other factors that may increase your risk can be changed, such as:

• Drug abuse from cocaine , amphetamines, or heroin use
• Smoking
• Physical inactivity

Certain medical condition can increase your risk of stroke. Management or prevention of these conditions can decrease your risk of stroke. Medical conditions that increase your risk include:

• High blood pressure
• High cholesterol levels—specifically high-LDL cholesterol
• Low bone mineral density, especially in women
• Obesity and metabolic syndrome
• Sleep apnea
• High blood homocysteine level
• Atherosclerosis
• Type 2 diabetes or impaired glucose tolerance
• Atrial fibrillation
• Blood disorders such as sickle cell disease and polycythemia
• Vascular dementia
• Disease of heart valves, such as mitral stenosis
• Prior stroke or cardiovascular disease, such as heart attack
• Peripheral artery disease
• Transient ischemic attack (TIA)—a warning stroke with stroke-like symptoms that go away shortly after they appear
• Conditions that increase your risk of blood clots such as:
  • Cancer
  • Certain autoimmune diseases
• Migraine with aura
• Having a blood vessel abnormality

Risk factors specific to women include:

• Previous pre-eclampsia
• Use of birth control pills , especially if you are over 35 years old and smoke
• Long-term use of hormone replacement therapy
• Menopause
• Pregnancy—due to increased risk of blood clots
• Psychological disorders, such as depression or anxiety

Symptoms

Symptoms occur suddenly. Exact symptoms will depend on the part of the brain that is affected. Rapid treatment is important to decrease the amount of brain damage. Brain tissue without blood flow dies quickly.

Call for emergency medical services right away if you notice any of the following sudden symptoms:

• Weakness or numbness of face, arm, or leg, especially on one side of the body
• Confusion
• Trouble speaking or understanding
• Trouble seeing in one or both eyes
• Lightheadedness, trouble walking, loss of balance, or coordination
• Severe headache with no known cause

Diagnosis

A physical exam will be done. The doctor will look for muscle weakness, visual and speech problems, and problems with basic movement. If possible, you will be asked about your symptoms and medical history.

Images of your brain and blood vessels may need to be taken with:

• CT scan
• MRI scan
• Magnetic resonance angiography (MRA)
• CT angiogram (CTA)
• Doppler ultrasound

Blood tests can also help determine if there is a bleeding problem.

Treatment

Immediate treatment is needed to open the blocked blood vessel. This should restore blood flow to the brain tissue and stop further damage. Treatment after immediate care will aim to:

• Reduce the chance of later strokes
• Improve function affected by the stroke
• Overcome disabilities

Supportive care may also include:

• Oxygen therapy
• Precautions to prevent choking

Medicine

Some will receive a group of drugs called thrombolytics. These medicines can rapidly dissolve blood clots. They are often given by IV, but can also be delivered directly to the blood clot. These medicines need to be given within hours after the start of symptoms to be most effective. That is why it is important to get medical help right away if stroke symptoms develop.

Aspirin and other medicine may be continued to decrease the risk of future blood clots. This may prevent future strokes from occurring.

To help manage other health issues and decrease the risk of future strokes the doctor may recommend medicine to:

• Decrease blood pressure
• Correct irregular heart rhythms

Surgery

An embolectomy may be needed. It will remove a clot and allow blood flow back into the area. A wire is passed through blood vessels to the clot. Tools will then be passed along the wire to do one of the following:

• Physically remove the clot
• Deliver clot-dissolving medicine directly to the clot

The stroke and damaged tissue can cause swelling in the brain. Surgery may be needed to relieve the pressure. One common option is to remove a section of the skull. This is called a craniotomy.

Rehabilitation

If brain tissue was damaged, rehabilitation can be an important part of your recovery. Rehabilitation may include:

• Physical therapy—to regain as much movement as possible
• Occupational therapy—to assist in everyday tasks and self care
• Speech therapy—to improve swallowing and speech challenges
• Psychological therapy—to improve mood and decrease depression

Prevention

Many of the risk factors for stroke can be changed. Lifestyle changes that can help reduce your chance of getting a stroke include:

• Exercise regularly.
• Eat more fruits, vegetables , and whole grains . Limit dietary salt and fat .
• If you smoke, talk to your doctor about ways to quit.
• Include fish in your diet.
• Drink alcohol only in moderation. This means no more than 1-2 drinks per day.
• Maintain a healthy weight.
• Check blood pressure frequently . Follow your doctor's recommendations for keeping it in a safe range.
• Take a low dose of aspirin if your doctor says it is safe.
• Keep chronic medical conditions under control. This includes high cholesterol and diabetes.
• Talk to your doctor about the use of a statins. These types of drugs may help prevent certain kinds of strokes in some people.
• Seek medical care if you have symptoms of a stroke. Seek care even if symptoms stop.
• If you use drugs, talk to your doctor about rehabilitation programs.