The disease known as stroke is caused by a critical deficiency of blood supply to the brain or a region of the brain. The effects of stroke upon the victim can range from long-term, gradually increasing problems such as dizzy spells and loss of motor skills, to sudden and unexpected death. In all cases, the cause of the stroke must be treated as soon as it is diagnosed in order to avoid risk to the patient. An ischemic stroke is caused by a partial or complete blockage of a blood vessel that supplies the brain such as the carotid or middle cerebral arteries.
Hemorrhagic stroke is caused by a break in a cerebral artery.
Each year in the U.S alone, over 700,000 people are diagnosed with one of the two types of stroke, and about 160,000 of these people die while another 200,000 suffer permanent debilitation. Once a patient actually suffers a stroke, treatment must be administered within a very short time for the best prognosis. Hemorrhagic stroke in particular has poor medical outcomes unless treatment is offered very soon after the hemorrhage begins. For victims of ischemic stroke, there is only about a 3 hour therapeutic time window in which thrombolytic drugs, such as TPA, can be given. Used properly, these drugs can save many thousands of lives, however, because of the nature of thrombolytic drugs, if given to a patient suffering from a brain hemorrhage, they will severely complicate the patient's condition, often resulting in death.