A stroke occurs when the blood flow in part of your brain is blocked. After just a few minutes, the starved brain
cells begin to die. Normally, the brain receives blood via two
major pairs of arteries, which branch throughout brain tissue, and supply your brain cells with
a constant flow of oxygen, glucose, and nutrients necessary for their functions. In one type of stroke, ischemic stroke, an artery in your brain narrows, or becomes completely blocked, preventing normal blood flow. The blockage may be caused by a blood clot, also called a thrombus, which forms in an unhealthy
artery of the brain. The lack of blood flow causes the tissue the artery supplies to become starved, or ischemic. Similarly, the blockage may be due to an embolus,
a blood clot that forms elsewhere in the body and travels to the brain. The embolus lodges in a narrow artery and obstructs blood flow. In contrast, during a hemorrhagic stroke, abnormal bleeding disrupts normal blood flow. For example, in an intracerebral hemorrhagic stroke, a blood vessel bursts, spilling blood directly onto your brain, while robbing the intended tissue of nourishment. Both the hemorrhage and ischemia destroy brain tissue. A subarachnoid hemorrhagic stroke occurs when a weak spot in a blood vessel wall, called an aneurysm, bursts and leaks blood into the tight space between your brain and your skull. The high-pressure bleeding results in serious damage to brain tissue. Immediate treatment for your stroke may help
to minimize brain cell injury and death. If you have an ischemic stroke, you may be given medication to break up the clot causing your stroke. Later, your doctor may recommend surgery, such as carotid endarterectomy, to reduce your risk of having another ischemic stroke. In the case of hemorrhagic stroke, emergency surgery may be necessary to repair damaged arteries, or reduce the pressure of the blood on your brain. You may be given medication to help the brain’s blood flow return to normal.