A stroke occurs when blood supply to the brain is suddenly interrupted or when a blood vessel in the brain bursts. Brain cells die if they do not receive sufficient oxygen or nutrients. The symptoms of a stroke include sudden weakness or numbness (especially on one side of the body), confusion or trouble talking, blurred vision, sudden trouble walking, dizziness, loss of balance, or sudden severe headache.
There are two major types of stroke:
Ischemic stroke: Ischemic stroke is the most common type. It accounts for about 90 percent of all strokes. It occurs when a blood clot, known as a thrombus, blocks the flow of blood in an artery responsible for delivering blood to the brain. Blood clots usually form in arteries damaged by fatty deposits, called atherosclerosis.
Hemorrhage stroke: A hemorrhage, or bleeding, from an artery in the brain can be caused by an aneurysm or a major head injury. Aneurysms are blood-filled pouches that balloon out from weak sections of the artery wall. They are often the result of high blood pressure. An aneurysm is not always dangerous, but one that bursts within the brain, can cause a hemorrhagic stroke.
Although stroke is a disease of the brain, it can affect the entire body. A common disability that results from stroke is hemiplegia, (complete paralysis on one side of the body). A stroke may cause problems with awareness, thinking, learning, attention, and judgment. Stroke survivors often have problems understanding or forming speech. A stroke can also lead to emotional problems. Stroke patients may have difficulty controlling their emotions or may act inappropriately as a result. Many stroke patients experience depression. Stroke survivors may also have numbness or strange sensations. The pain is often worse in the hands and feet and is made worse by movement and temperature changes, particularly cold temperatures.
National Institute of Neurological Disorders and Stroke