Stroke or "brain attack" happens when the blood supply to the brain is disrupted or blocked. Without blood and the oxygen it carries, part of the brain starts to die. The part of the body controlled by the damaged area of the brain can't work properly. The disruption may be due to a torn or blocked artery leading to the brain which is potentially life threatening.
Stroke may result to the impairment of mental or bodily functions such as loss of sensation, consciousness, perception, or speech. A stroke can be fatal and requires immediate medical attention. Complications may range from severe paralysis and mental impairment to coma and death.
Stroke can be classified into the following:
- Ischemic Stroke. In everyday life, blood clotting is beneficial. When you are bleeding from a wound, blood clots work to slow and eventually stop the bleeding. In the case of stroke, blood clots are dangerous because they can block arteries and cut off blood flow, this process is called ischemia. An ischemic stroke may be due to embolism (a blood clot that blocks the artery) and thrombosis (blood clot in the brain artery that has been narrowed by fatty deposits).
- Embolic Stroke. In this type, a blood clot forms somewhere in the body (usually the heart) and travels through the bloodstream to your brain. Once in your brain, the clot eventually travels to a blood vessel small enough to block its passage. The clot lodges there, blocking the blood vessel and causing a stroke. The medical word for this type of blood clot is embolus.
- Thrombotic Stroke. In the second type of blood-clot stroke, blood flow is impaired because of a blockage to one or more of the arteries supplying blood to the brain. The process leading to this blockage is known as thrombosis. Strokes caused in this way are called thrombotic strokes. That's because the medical word for a clot that forms on a blood-vessel deposit is thrombus.
- Large Vessel Thrombosis. Most large vessel thrombosis is caused by a combination of long-term atherosclerosis followed by rapid blood clot formation. Thrombotic stroke patients are also likely to have coronary artery disease, and heart attack is a frequent cause of death in patients who have suffered this type of brain attack.
- Small Vessel Disease/Lacunar Infarction. Occurs when blood flow is blocked to a very small arterial vessel. The term's origin is from the Latin word lacuna which means hole, and describes the small cavity remaining after the products of deep infarct have been removed by other cells in the body. Little is known about the causes of small vessel disease, but it is closely linked to high blood pressure.
- Hemorrhagic Stroke is caused by the breakage or "blowout" of a blood vessel in the brain. Hemorrhages can be caused by a number of disorders which affect the blood vessels, including long-standing high blood pressure and cerebral aneurysms. An aneurysm is a weak or thin spot on a blood vessel wall. Aneurysms develop over a number of years and usually don't cause detectable problems until they break. Two types of hemorrhagic stroke include subarachnoid and intracerebral. In an intracerebral hemorrhage, bleeding occurs from vessels within the brain itself.
Hypertension is the primary cause of this type of hemorrhage. In a subarachnoid hemorrhage, an aneurysm bursts in a large artery on or near the thin, delicate membrane surrounding the brain. Blood spills into the area around the brain, which is filled with a protective fluid, causing the brain to be surrounded by blood-contaminated fluid.
Anyone can have a stroke, but, the chances of having a stroke increase if a person has certain risk factors, or criteria that can cause a stroke. There are 2 types of risk factors for stroke: controllable (involves lifestyle and medical factors) and uncontrollable.
Commonly Prescribed Drugs
The treatment depends whether the stroke is caused by blood clots (ischemia) or by bleeding around the brain (hemorrhagic).
- Tissue Plasminogen Activator (tPA) dissolves the blood clot and improves blood flow to brain. It must be administered as soon as possible or within 4 hours after the stroke has occurred to increase chance of recovery.
- Anti-platelets reduce blood clotting formation by preventing platelets from sticking together.
- Anti-coagulants reduce the ability of the blood to clot by inhibiting blood clotting factors.
- Antihypertensive agents lower blood pressure. High blood pressure is one of the major causes of stroke.
- Statins lower cholesterol levels in the blood. High cholesterol level builds up plaque in the artery walls (atherosclerosis). This plaque clogs the arteries which reduces the blood flow that may lead to a stroke or heart attack.