Stroke, also known as a Cerebrovascular Accident, or CVA, is a cerebral circulation disorder that reduces or even stops the flow of blood in a certain part of the brain. Stroke is one of the main causes or deterioration of brain function in adults. From the perspective of modern medicine, a stroke is a severe and extremely dangerous vascular lesion of the central nervous system.
Cerebral Accident progresses quite quickly – from several minutes to several hours (less frequently – during several days). The periods following a stroke are conditionally divided into:
- Acute period (up to 3 weeks);
- Recovery period (up to 1 year);
- Residual period (over 1 year).
Both pathological processes, such as the growth of cerebral edema (swelling), and the processes that contribute to the recovery, improvement of the blood supply, take place during the acute period. When the blood supply increases in the areas surrounding a lesion, there is a reduction in the size of the hemorrhage and a decrease in the compression effect produced on the surrounding brain matter.
Each year over 15 million people have cerebral accidents. Stroke may lead to a long-term coma, paralyses or pareses (muscular weakness) of one side of the face or body, and disturbance of the mind and/or memory. Severe stroke may cause death.
There are two main types of stroke:
- Hemorrhagic stroke – usually develops suddenly, in the daytime, during physical or emotional stress, and more often in people ages 45 to 60 years. It most often happens because of the rupture of an artery, with the effused blood soaking into some part of the brain. This type of stroke is sometimes also called an intra-cerebral hemorrhage.
Most often Hemorrhagic Stroke occurs in people suffering from high blood pressure (Arterial Hypertension) and develops in the setting of the increase in blood pressure. When the vascular wall can no longer sustain the sharp increase of blood pressure, it bursts.Aneurysm rupture is a rare cause of this type of stroke. Arterial Aneurysm is usually a bulge that has developed on the arterial wall. The rupture of the vessel located on the brain surface causes penetration of blood into the area that surrounds the brain (subarachnoid space). This subtype of stroke is called Subarachnoid Hemorrhage (a hematoma caused by the ruptures of the vessels in the arachnoid membranes formed between the membranes surrounding the brain and spinal cord (pia mater);
- Ischemic stroke – most commonly develops in people over 50 years of age, but it also may occur at a younger age. Most often it develops due to the narrowing or - blockage of the arteries – the vessels that supply the brain with blood – with an atherosclerotic plaque, or blood clot. This type of stroke is also called a Cerebral Infarction by analogy with Myocardial Infarction. 80% of strokes are ischemic in nature.
In both cases, the cells of the damaged brain stop receiving sufficient amounts of oxygen and required nutrient materials and; thus they begin to die.
Also, stroke can be classified according to the duration of the neurological symptoms:
- Transient ischemic attack – the duration of symptoms and complete recovery period is 24 hours;
- Minor stroke - the duration of symptoms and complete recovery period is from 24 hours to 3 weeks;
- Completed ischemic stroke – the duration of the symptoms is more than 3 weeks.