A stroke is a potentially life-threatening event that occurs when part of the brain is deprived of adequate oxygen. Also known as a cerebrovascular accident (CVA) or a “brain attack,” a stroke occurs when a blood vessel in the brain bursts or becomes clogged by a blood clot or other materials. Thie blockage of brain blood vessels prevents oxygen and nutrients from getting to nerve cells in the affected area of the brain. Without adequate oxygen these nerve cells typically die within minutes, and the area of the body that they control can cease to function. This damage can be permanent, especially if the patient is not immediately treated.

Each year, approximately 700,000 strokes occur in the United States, of which 500,000 are new (first-time) strokes, according to the Centers for Disease Control and Prevention. More than 160,000 Americans die every year from strokes. Strokes are the third leading cause of death in the United States, behind heart disease and cancer, according to the National Stroke Association. 

Immediate response to a stroke can help prevent damage, but a stroke left untreated for too long may result in irreversible nerve and tissue damage that can cause symptoms such as a permanent loss of speech or paralysis. It can even lead to death. Damage to the brain due to a stroke can result in disabilities throughout the body that may be mild to severe. Complications associated with strokes include:

• Emotional problems. Some stroke patients have difficulty controlling their emotions and may express inappropriate emotions. Others may become depressed. People may cry easily or undergo sudden mood swings for no apparent reason. This is known as emotional lability.
  
  
• Paralysis and weakness. Strokes may cause complete paralysis on one side of the body (hemiplegia) or weakness that appears on one side of the body (hemiparesis).
  
  
• Problems with language involving speaking and understanding (aphasia) and problems with thinking. Stroke survivors may have trouble initiating and/or understanding speech. They may also struggle with cognitive skills such as attentiveness, awareness, judgment, learning, memory and thinking.
  
  
• Sensation and perception changes. Patients who have had a stroke may experience numbness or other unusual sensations. Pain or numbness may be experienced in the hands and feet, and may worsen with movement or temperature changes, particularly at lower temperatures. Patients may also find that their perception of everyday objects has changed due to an impaired ability to see, touch, move or think.
  
  
• Difficulties chewing and swallowing (dysphagia). A stroke may weaken muscles on one or both sides of the mouth, leading to difficulty with chewing and swallowing.

The diagnosis, treatment and prevention of strokes are complicated because there are two major distinct types of strokes – ischemic and hemorrhagic strokes – and they are distinctly different. An ischemic stroke involves a clot or blockage in an artery, while a hemorrhagic stroke involves bleeding inside or around the brain. Of the two forms of stroke, hemorrhagic stroke generally poses more immediate danger because increased pressure on the brain due to bleeding can cause death.

Yet, people who survive a stroke tend to recover more fully if the stroke was hemorrhagic rather than ischemic. This is because the damage in a hemorrhagic stroke is caused by pressure on the brain and may be reversible once the pressure is relieved. In contrast, the damage associated with an ischemic stroke is a result of blockage in an artery that results in death of the affected brain tissues. When this occurs recovery is more difficult.  

In recent years, there have been advances in the immediate care and treatment of strokes as physicians have become better at diagnosing what type of stroke has occurred and moving quickly to treat it. This has resulted in higher survival rates, and a corresponding higher rate of hospitalization from strokes as more people survive their strokes.