Strokes

 

A stroke, sometimes called a brain attack, occurs when something blocks blood supply to part of the brain or when a blood vessel in the brain bursts.

In either case, parts of the brain become damaged or die. A stroke can cause lasting brain damage, long-term disability, or even death.

The brain controls our movements, stores our memories, and is the source of our thoughts, emotions, and language. The brain also controls many functions of the body, like breathing and digestion.

To work properly, your brain needs oxygen. Your arteries deliver oxygen-rich blood to all parts of your brain. If something happens to block the flow of blood, brain cells start to die within minutes, because they canít get oxygen. This causes a stroke.

A stroke happens in one of two ways: a blocked artery or a ruptured artery.

 

Types of strokes:

Ischemic Stroke (Clots)

Occurs when a blood vessel supplying blood to the brain is obstructed. It accounts for 87 % of all strokes.

Fatty deposits lining the vessel walls, called atherosclerosis, are the main cause for ischemic stroke. Fatty deposits can cause two types of obstruction:

Silent Stroke

You could have a stroke and not know it. Silent cerebral infarction (SCI), or silent stroke, is a brain injury likely caused by a blood clot that interrupts blood flow in the brain. Itís a risk factor for future strokes and a sign of progressive brain damage.

Hemorrhagic Stroke (Bleeds)

Occurs when a weakened blood vessel ruptures. The two types of weakened blood vessels that usually cause hemorrhagic stroke are aneurysms and arteriovenous malformations (AVMs). The most common cause of hemorrhagic stroke is uncontrolled high blood pressure.

TIA (Transient Ischemic Attack)

Called a mini-stroke, itís caused by a serious temporary clot. This is a warning sign stroke and should be taken seriously.

Cryptogenic Stroke

In most cases, a stroke is caused by a blood clot that blocks the flow of blood to the brain. In some instances, despite testing, the cause of a stroke canít be determined. This is called a cryptogenic stroke.

Brain Stem Stroke

When stroke occurs in the brain stem, it can affect both sides of the body and may leave someone in a Ďlocked-iní state. When a locked-in state occurs, the patient is generally unable to speak or move below the neck. 

 

Symptoms

 

Symptoms of stroke depend on which part of the brain is damaged. In some cases, a person may not know that a stroke has occurred.

Most of the time, symptoms develop suddenly and without warning. But symptoms may occur on and off for the first day or two. Symptoms are usually most severe when the stroke first happens, but they may slowly get worse.

A headache may occur if the stroke is caused by bleeding in the brain. The headache:

       Starts suddenly and may be severe

       May be worse when you are lying flat

       Wakes you up from sleep

       Gets worse when you change positions or when you bend, strain, or cough

Other symptoms depend on how severe the stroke is, and what part of the brain is affected. Symptoms may include:

       Change in alertness (including sleepiness, unconsciousness, and coma)

       Changes in hearing or taste

       Changes that affect touch and the ability to feel pain, pressure, or different temperatures

       Confusion or loss of memory

       Problems swallowing

       Problems writing or reading

       Dizziness or abnormal feeling of movement (vertigo)

       Eyesight problems, such as decreased vision, double vision, or total loss of vision

       Lack of control over the bladder or bowels

       Loss of balance or coordination, or trouble walking

       Muscle weakness in the face, arm, or leg (usually just on one side)

       Numbness or tingling on one side of the body

       Personality, mood, or emotional changes

       Trouble speaking or understanding others who are speaking

 

Causes

 

There are two major types of stroke:

       Ischemic stroke

       Hemorrhagic stroke

Ischemic stroke occurs when a blood vessel that supplies blood to the brain is blocked by a blood clot. This may happen in two ways:

       A clot may form in an artery that is already very narrow. This is called a thrombotic stroke.

       A clot may break off from another place in the blood vessels of the brain, or from some other part of the body, and travel up to the brain. This is called cerebral embolism, or an embolic stroke.

Ischemic strokes may also be caused by a sticky substance called plaque that can clog arteries.

A hemorrhagic stroke occurs when a blood vessel in part of the brain becomes weak and bursts open. This causes blood to leak into the brain. Some people have defects in the blood vessels of the brain that make this more likely. These defects may include:

       Aneurysm (weak area in the wall of a blood vessel that causes the blood vessel to bulge or balloon out)

       Arteriovenous malformation (AVM; abnormal connection between the arteries and veins)

       Cerebral amyloid angiopathy (CAA; condition in which proteins called amyloid build up on the walls of the arteries in the brain)

Hemorrhagic strokes may also occur when someone is taking blood thinners, such as warfarin (Coumadin). Very high blood pressure may cause blood vessels to burst, leading to hemorrhagic stroke.

An ischemic stroke can develop bleeding and become a hemorrhagic stroke.

High blood pressure is the main risk factor for strokes. Other major risk factors are:

       Irregular heartbeat, called atrial fibrillation

       Diabetes

       Family history of stroke

       Being male

       High cholesterol

       Increasing age, especially after age 55

       Ethnicity (African Americans are more likely to die of a stroke)

       Obesity

       History of prior stroke or transient ischemic attack (occurs when blood flow to a part of the brain stops for a brief time)

Stroke risk is also higher in:

       People who have heart disease or poor blood flow in their legs caused by narrowed arteries

       People who have unhealthy lifestyle habits such as smoking, excessive use of alcohol, use recreational drugs, a high-fat diet, and lack of exercise

       Women who take birth control pills (especially those who smoke and are older than 35)

       Women who are pregnant have an increased risk while pregnant

       Women who take hormone replacement therapy

       Patent foramen ovale (PFO), a hole between the left and right atria (upper chambers) of the heart