Stroke

Brain cells need a constant supply of oxygen and nutrients. They are delivered by a network of blood vessels that reach every part of the brain. When something cuts off that supply, brain cells downstream begin to die. The injury that follows is called a stroke.

Most strokes strike when a blood clot becomes lodged in one of the brain's arteries, blocking blood flow. In some cases, the clot forms inside the artery, usually because a cholesterol-filled plaque inside the artery breaks open. This is called a thrombotic stroke. In other cases, a blood clot or a solid mass of debris that originates elsewhere travels to the brain, where it blocks a brain artery. This is called an embolic stroke. A third type of stroke, hemorrhagic stroke, occurs when a blood vessel in the brain bursts.

Since different areas of the brain are responsible for different functions, symptoms of stroke vary. They can be changes in sensation, movement, sight, speech, balance, and coordination. Sometimes a stroke is preceded by one or more transient ischemic attacks (TIAs). These are brief episodes of stroke-like symptoms that last for a few minutes — or possibly up to 24 hours — but that go away on their own.

If you think that you, or someone you are with, is having a stroke, call 911 right away. The sooner you call, the sooner treatment can begin — "time is brain," as emergency room doctors say. The type of treatment depends on the type of stroke that has occurred. If the brain's blood supply is restored quickly and completely, a full recovery with little or no disability is possible. The more widespread the damage, and the greater delay of treatment, the more severe and long-lasting the damage.

Recovery after a stroke depends on how well healthy areas of the brain take over duties that had been performed by the damaged brain tissue. To some extent, especially in children and young adults, recovery is possible because of the brain's ability to compensate for damage in one area by working harder in another — by relying on alternate wiring for some functions or by rewiring around the injured site. When such rewiring isn't possible, rehabilitation techniques can help the brain recover function.

Stroke Articles

Stroke Overview

A stroke is a brain injury that occurs because the brain's blood supply is interrupted. The brain's blood supply can be disrupted for different reasons. Doctors generally classify strokes into three categories, depending on the cause: Hemorrhagic stroke — Bleeding (hemorrhage) causes this type of stroke. Bleeding can occur within the brain or between the brain and the skull. When bleeding occurs, small blood vessels near the hemorrhage tighten in a spasm. As a result, some brain areas get too little blood flow. A hemorrhagic stroke that occurs within the brain is called an intracerebral hemorrhage. It often is linked to high blood pressure, old age, heavy alcohol use, or the use of cocaine or methamphetamines. A stroke that occurs between the brain and the skull is called a subarachnoid hemorrhage. Hemorrhagic strokes are much less common than strokes caused by clots. (Locked) More »

Carotid Ultrasound (Carotid Doppler)

A Carotid ultrasound shows the amount of blood flow in the carotid arteries, the major blood vessels to the brain located on either side of your neck. With this imaging technique, your doctor can see if there is any narrowing of your carotid arteries because of cholesterol deposits or some other problem. This test is often used to evaluate people who have had a stroke or who might be at high risk for one because of reduced blood flow in the carotid arteries. (Locked) More »

Hemorrhagic Stroke

A hemorrhagic stroke is bleeding (hemorrhage) that suddenly interferes with the brain's function. This bleeding can occur either within the brain or between the brain and the skull. Hemorrhagic strokes account for about 20% of all strokes, and are divided into categories depending on the site and cause of the bleeding: Intracerebral hemorrhage — Bleeding occurs from a broken blood vessel within the brain. Some things that increase your risk for this kind of hemorrhage are high blood pressure (hypertension), heavy alcohol use, advanced age and the use of cocaine or amphetamines. Other kinds of stroke can convert to an intracerebral hemorrhage. For example, a stroke that begins without hemorrhage (a thrombotic or embolic stroke) can lead to intracerebral hemorrhage shortly afterward. This is especially common for embolic strokes that are related to a heart valve infection (endocarditis). In this case, a clump of bacteria and inflammatory cells from the valve infection can become a floating mass within the bloodstream (called an embolus). The infected clump can travel into a brain artery and become wedged there. Then, the infection can spread through the artery. In rare cases, intracerebral hemorrhage may happen because of a leaking arteriovenous malformation (AVM), which is an abnormal and weak-walled blood vessel that connects an artery and a vein. This weak blood vessel is present from birth—it is larger than a capillary so blood that flows in can be at high pressure, causing the AVM to eventually stretch or leak. Subarachnoid hemorrhage — Bleeding from a damaged blood vessel causes blood to accumulate at the surface of the brain. Blood fills a portion of the space between the brain and the skull, and it mixes with the cerebrospinal fluid that cushions the brain and spinal cord. As blood flows into the cerebral spinal fluid, it increases pressure on the brain, which causes an immediate headache. In the days immediately following the bleeding, chemical irritation from clotted blood around the brain can cause brain arteries that are near to this area to go into spasm. Artery spasms can damage brain tissue. Most often, a subarachnoid hemorrhage happens because of a leaking saccular aneurysm (a sack-like bulge in the wall of an artery), but it also can occur because of leakage from an arteriovenous malformation. (Locked) More »

Thrombotic Stroke

In a thrombotic stroke, a blood clot (thrombus) forms inside one of the brain's arteries. The clot blocks blood flow to a part of the brain. This causes brain cells in that area to stop functioning and die quickly. The blood clot that triggers a thrombotic stroke usually forms inside an artery that already has been narrowed by atherosclerosis. This is a condition in which fatty deposits (plaques) build up inside blood vessels. (Locked) More »

Transient Ischemic Attack (TIA)

A transient ischemic attack (TIA) is an episode of stroke-like symptoms. It usually lasts less than one hour. A TIA is sometimes called a ministroke. During a TIA, circulation to a part of the brain is interrupted briefly, then restored. This interruption can be caused by: A narrowing of a brain artery because of atherosclerosis. A small floating blood clot. This clot enters the bloodstream from somewhere else in the body, often the heart. It temporarily blocks a brain artery. (Locked) More »