A stroke is a potentially life-threatening event in which part of the brain is deprived of adequate oxygen. Also known as a cerebrovascular accident (CVA), a stroke can be very dangerous. 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.

There are two types of strokes. An ischemic stroke occurs when the blood supply to the brain is interrupted, usually by a blood clot. The second kind of stroke is a hemorrhagic stroke, which occurs when there is bleeding into or around the brain. Almost 90 percent of all strokes are ischemic, while the remainder are hemorrhagic, according to the American Heart Association.

When blood flow to the brain stops, brain cells begin to die because they do not receive the oxygen and nutrients they need to survive. Survival and potential recovery from a stroke depend on quick access to medical care. In recent years, the mortality rate from strokes has fallen, thanks to advances in immediate stroke treatment.

Symptoms of a stroke can vary depending on the type of stroke that has occurred. However, the National Institute of Neurological Disorders and Stroke (NINDS) lists several major general signs of stroke. All of these symptoms appear suddenly:

• Numbness or weakness of the face, arms or legs
  
  
• Confusion
  
  
• Trouble speaking or understanding language (aphasia)
  
  
• Trouble seeing in one or both eyes (vision loss)
  
  
• Difficulty walking
  
  
• Dizziness
  
  
• Loss of balance and coordination (ataxia)
  
  
• Severe headache (without a known cause)

When a patient shows symptoms of a stroke, the physician will promptly evaluate the patient’s medical history and immediately perform brain imaging tests such as a computed axial tomography (CAT) scan. Prompt treatment focuses on re-establishing blood flow to the brain and stabilizing the patient. Medications, surgery and rehabilitation (e.g. physical therapy) may be part of the overall treatment process.