Neuroscience & Stroke

Stroke Facts

A stroke, also often called a "brain attack," occurs when blood flow to the brain is cut off by a blood clot or a ruptured blood vessel. Starving brain cells begin to die within minutes, so seeking immediate treatment is critical.

  • Stroke is our nation’s number 3 killer and a leading cause of disability.
  • Each year, about 700,000 Americans have a stroke.
  • On average, one stroke occurs every 45 seconds.
  • Every 3 minutes, someone dies of stroke.
  • Stroke causes about one in 15 deaths.
  • 15 to 30 percent of stroke survivors are permanently disabled.

Stroke is Highly the First Three Hours

  • For every hour’s delay, the brain loses 120 million cells.
  • In volume, a pea-sized piece of brain dies for each 12 minutes without treatment.
  • Brain tissue a little larger than a ping-pong ball is lost if a typical stroke is untreated.
  • The brain ages 3.6 years in the first hour...36 years during a typical 10-hour stroke.

Types of Stroke

Stroke can be caused either by a clot obstructing the flow of blood to the brain (ischemic stroke) or by a blood vessel rupturing and preventing blood flow to the brain (hemorrhagic stroke).

Ischemic stroke, which typically accounts for more than 80 percent of all strokes, occurs as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls. This condition is called atherosclerosis. These fatty deposits can cause two types of obstruction:

  • Cerebral thrombosis: A thrombus (blood clot) that develops at the clogged part of the vessel.
  • Cerebral embolism: Generally, a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain's blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain.

Transient ischemic attacks, also called TIAs, are minor or warning strokes. In a TIA, conditions indicative of an ischemic stroke are present and the typical stroke warning signs develop. However, the obstruction (blood clot) occurs for a short time and tends to resolve itself through normal mechanisms. Even though the symptoms disappear after a short time, TIAs are strong indicators of a possible major stroke. Steps should be taken immediately to prevent a stroke.

Hemorrhagic stroke accounts for fewer than 20 percent of stroke cases and results from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. The two types of hemorrhagic strokes are intracerebral hemorrhage or subarachnoid hemorrhage.

Two types of weakened blood vessels usually cause hemorrhagic stroke: aneurysms and arteriovenous malformations (AVMs).

  • An aneurysm is the ballooning of a weakened region of a blood vessel. If left untreated, the aneurysm continues to weaken until it ruptures and bleeds into the brain.
  • AVM is a cluster of abnormally formed blood vessels. Any of these vessels can rupture, causing bleeding into the brain.