Stroke

A stroke occurs when the blood supply to part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and nutrients. Within minutes, brain cells begin to die.

A stroke is a medical emergency. Prompt treatment is crucial. Early action can minimize brain damage and potential complications.

Approximately 185,000 people die from stroke each year, making it the fifth leading cause of death in America. It is also a leading cause of adult disability for those who survive stroke.

There are two kinds of stroke. The more common kind, called ischemic stroke, is caused by a blood clot that blocks or plugs a blood vessel in the brain. The other kind, called hemorrhagic stroke, is caused by a blood vessel that breaks and bleeds into the brain. "Mini-strokes" or transient ischemic attacks (TIAs), occur when the blood supply to the brain is briefly interrupted.

Symptoms of stroke are:

• sudden numbness or weakness of the face, arm or leg (especially on one side of the body)
• sudden confusion, trouble speaking or understanding speech
• sudden trouble seeing in one or both eyes
• sudden trouble walking, dizziness, loss of balance, or coordination
• sudden severe headache with no known cause

If you have any of these symptoms, you must get to a hospital quickly to begin treatment. Therapies try to stop a stroke while it is happening by quickly dissolving the blood clot or by stopping the bleeding. Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. Drug therapy with blood thinners is the most common treatment for stroke.

A stroke occurs when the blood supply to your brain is interrupted or reduced. A stroke may be caused by a blocked artery (ischemic stroke) or the leaking or bursting of a blood vessel (hemorrhagic stroke). Some people may experience only a temporary disruption of blood flow to their brain (transient ischemic attack or TIA).

Most strokes (about 85 percent) are ischemic strokes. Ischemic strokes occur when the arteries to your brain become narrowed or blocked, causing severely reduced blood flow (ischemia). The most common ischemic strokes include thrombotic stroke and embolic stroke. A thrombotic stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot may be caused by fatty deposits (plaque) that build up in arteries and cause reduced blood flow (atherosclerosis) or other artery conditions. An embolic stroke occurs when a blood clot or other debris forms away from your brain — commonly in your heart — and is swept through your bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus.

Hemorrhagic stroke occurs when a blood vessel in your brain leaks or ruptures. Brain hemorrhages can result from many conditions that affect your blood vessels, including uncontrolled high blood pressure (hypertension), overtreatment with anticoagulants, and weak spots in your blood vessel walls (aneurysms).

Types of hemorrhagic stroke include intracerebral hemorrhage and subarachnoid hemorrhage. In an intracerebral hemorrhage, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging brain cells. Brain cells beyond the leak are deprived of blood and also damaged. High blood pressure, trauma, vascular malformations, use of blood-thinning medications, and other conditions may cause an intracerebral hemorrhage.

In a subarachnoid hemorrhage, an artery on or near the surface of your brain bursts and spills into the space between the surface of your brain and your skull. This bleeding is often signaled by a sudden, severe headache. A subarachnoid hemorrhage is commonly caused by the bursting of a small sack-shaped or berry-shaped outpouching on an artery known as an aneurysm. After the hemorrhage, the blood vessels in your brain may widen and narrow erratically (vasospasm), causing brain cell damage by further limiting blood flow.

A TIA — also known as a mini-stroke — is a brief period of symptoms similar to those you would have in a stroke. A temporary decrease in blood supply to part of your brain causes TIAs, which often last less than five minutes. Like an ischemic stroke, a TIA occurs when a clot or debris blocks blood flow to part of your brain. A TIA does not leave lasting symptoms because the blockage is temporary. A TIA is a warning sign for a future stroke, and more than one-third of people who have a TIA have a stroke within 1 year if they do not receive treatment.

It is not possible to tell if you are having a stroke or a TIA only on the basis of your symptoms.

Many factors can increase your risk of a stroke, including:

• being overweight or obese
• physical inactivity
• heavy or binge drinking
• using illicit drugs such as cocaine and methamphetamines
• high blood pressure
• cigarette smoking or exposure to secondhand smoke
• high cholesterol
• diabetes
• obstructive sleep apnea — a sleep disorder in which the oxygen level intermittently drops during the night
• cardiovascular disease, including heart failure, heart defects, heart infection, or abnormal heart rhythm
• personal or family history of stroke, heart attack or transient ischemic attack.
• being age 55 or older
• African-American race
• being male

Call 911 immediately at the first signs of stroke using FAST: Face drooping, Arm weakness, Speech difficulty, Time to call. Sudden numbness, confusion, trouble seeing or walking, or a severe headache also need emergency care; fast treatment saves brain function.