Stroke Basics


About 1 out of every 320 people will have a stroke. There is a good chance that someday you will meet someone who has had a stroke, so you might be interested to know what they are going through.

The brain

A stroke occurs when a lack of blood supply affects the function of a specific region of the brain. The brain is an important body organ that has many interacting regions that work to control a variety of functions- from thinking, to vision, to movement, to coordination, to sensation, to vital functions such as breathing and sustaining life.

These regions work together in a coordinated, sophisticated fashion. Proper brain function requires blood supply for the delivery of nutrients and oxygen. Blood is delivered to the brain through a group of blood vessels that travel to and through the brain. The blood vessels include the carotid arteries, the cerebral arteries, and the vertebral arteries. Any decrease in blood supply to a portion of the brain results in impairment of the brain functions controlled by that region of the brain. That is how a stroke happens.

What happens?

When blood supply to an area of the brain is diminished, even temporarily, the brain tissue suffers from ischemia- a lack of the oxygen and nutrients it needs to function. Ischemia to a region of the brain causes decreased function of that region. When ischemia lasts longer than a few minutes, the affected brain tissue actually dies and ceases to function. This is a stroke.

TIA and silent stroke

The effects of diminished blood supply may last for only a short time if the ischemia is brief and quickly restored. A brief period of ischemia results in a transient ischemic attack (TIA). When ischemia occurs in a small region of the brain that controls functions that are also controlled elsewhere in the brain, a silent stroke, or an unnoticeable stroke, may result.

Blood vessels

The blood supply to the brain can be interrupted due to blockage, bleeding or low blood flow. Blockage can be caused by blood clot that develops within the blood vessel (infarct) or a blood clot that arrived from another location and lodged in the blood vessel (thrombus.) A bleeding blood vessel in the brain can result from a rupture of a defective blood vessel or from extreme blood pressure instability. In rare instances, a severe infection or an air bubble can block a blood vessel, causing a stroke. 

When a blood vessel breaks and bleeds, the brain is harmed by ischemia due to interruption of blood flow. However, when bleeding or hemorrhage occurs, irritation from the blood near the brain tissue also causes pain and neurological symptoms, in addition to the stroke symptoms caused by ischemia.

Depending on the blood vessel affected by a stroke and the part of the brain that is impaired, the initial symptoms and long-term effects may differ.

A stroke can cause any combination of the following symptoms 

  • Weakness of one side of the body
  • Numbness, tingling or unusual sensations 
  • Trouble walking
  • Coordination problems 
  • Vision loss or decrease in vision
  • Blurred vision or double vision 
  • Slurred speech 
  • Trouble communicating 
  • Trouble understanding words
  • Face asymmetry
  • Droopy eyelid
  • Dizziness
  • Headache
  • Confusion

What to do

Recognition of stroke symptoms is important. Diagnosis may require medical specialists. Prompt diagnosis is necessary because treatment for stroke requires careful, high level, decision making. The most effective treatments for stroke are most successful when administered promptly.


Treatment consists of methods that allow reestablishment of blood supply to the ischemic brain tissue and stabilization of health and vital functions to allow for optimal recovery. Reestablishment of blood supply is tricky- in some instances, in can result in bleeding. In the initial stage of a stroke, the ischemic tissue is prone to bleeding, so extreme care must be taken with re-establishment of blood flow.


Long-term effects of a stroke vary tremendously. Recovery includes physical rehabilitation and supportive care. Prevention of recurrent stroke and addressing underlying risk factors is a critical component of stroke recovery.

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