A stroke is a frightening event for the individual who suffers the stroke as well as for his/her family and friends. As the name stroke implies, it is a medical emergency that sometimes seems to hit without warning and that can be an overwhelming experience.
“Stroke” refers to damage that results when an interruption in blood supply occurs in the brain. Stroke affects 500,000 people in the United States every year and is the leading cause of adult disability.
Recently, new treatments have been developed that can reverse the devastating effects of a stroke. In order to maximize the chance of a good outcome after a stroke, it is necessary to know the warning signs and understand the importance of seeking immediate medical attention. Once a stroke occurs and the critical “time window” of intervention has past, supportive care, rehabilitation and time are the mainstay of treatment.
Understanding Your Body
In order to understand what happens during a stroke, it is helpful to take a closer look at the brain. The brain continuously sends electrical messages down the spinal cord, out to the nerves and into muscles and organs throughout the body. At the same time, the brain receives and processes incoming messages back from the body. This sending, receiving and processing controls how we move, think, feel and behave.
Specific areas of the brain control specific functions, for example, an area is responsible for movement, another for vision, another for hearing and still others for speech. All of these brain activities require a great deal of energy, which the brain receives from the blood. The heart delivers the blood to the brain through several large arteries known as the internal carotid arteries and vertebral arteries. These arteries divide into many smaller branches within the brain. Here, the oxygen and nutrients carried by the blood are delivered to the brain tissue, providing it with the energy it needs to function. Interruptions in blood supply to the brain, a blood clot or a ruptured blood vessel may result in a stroke, which deprive the brain of nutrients, oxygen and energy.
Types of Stroke
One of the most frequent types of strokes occurs when a fatty deposit known as plaque builds up on the artery walls. This can decrease the blood flow to the neighboring tissue, causing impaired brain function. Also, a blood clot, which is called a thrombus, can develop on the surface of the plaque and may completely block the flow of blood to a portion of the brain. Without oxygen or nutrients, the brain tissue no longer functions. This is called an ischemic stroke.
Another kind of ischemic stoke is caused by a wandering blood clot, which originates either in the heart or the arteries leading to the brain. This wandering clot, which is called an embolus, flows with the blood to the blood vessels of the brain. When the blood vessels become too narrow for the embolus to pass, it can block the flow of blood. This is called an embolism.
Not all strokes are caused by plaque or blood clots blocking an artery. A blood vessel may rupture and bleed within the brain or near the brain. This is known as a hemorrhagic stroke. When this happens, the brain tissue downstream from the rupture no longer gets enough blood or oxygen and dies.
When an area of the brain is injured by a stroke, the functions that are controlled by the area of the brain where the stroke occurred are lost.
Who Suffers from Stroke?
Stroke is the third leading cause of death in the United States and the No. 1 cause of adult disability. No member of society is spared the risk of stroke. Several American presidents have suffered fatal strokes in the 20th century including President Nixon and President Roosevelt.
There are nearly 750,000 first ever or recurrent strokes each year in the U.S. and over 150,000 deaths directly related to strokes. Nearly one-third of all strokes affect individuals under the age of 65; stroke is by no means limited to older individuals.
There are many risk factors for stroke. Risk factors that cannot be changed or prevented, which are called “non modifiable risk factors,” include aging, a history of stroke or other cardiovascular disease (related to the heart or blood vessels) in the family and a personal history of stroke. Modifiable risk factors include high blood pressure, smoking, diabetes, heart disease (especially an abnormal heart rhythm), high cholesterol, physical inactivity and illegal drug use (especially cocaine). Recent studies have also identified factors in the blood that can predispose to stroke by making the blood sticky or inflamed.