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 a few minutes, brain cells begin to die.

Stroke is a medical emergency, and prompt treatment of a stroke is crucial. Early treatment can minimise damage to your brain and potential stroke complications.

Types of stroke:

Ischemic stroke

About 80 per cent of strokes are ischemic strokes. They occur when the arteries to your brain are narrowed or blocked, causing severely reduced blood flow (ischemia). This deprives your brain cells of oxygen and nutrients, and cells may begin to die within minutes. The most common ischemic strokes are:

Thrombotic stroke

This type of stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot usually forms in areas damaged by atherosclerosis - a disease in which the arteries are clogged by fatty deposits (plaques). This process can occur within one of the two carotid arteries of your neck that carry blood to your brain, as well as in other arteries of the neck or brain.

Embolic stroke

An embolic stroke occurs when a blood clot or other obstruction forms in a blood vessel 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. It's often caused by irregular beating in the heart's two upper chambers (atrial fibrillation). This abnormal heart rhythm can lead to poor blood flow and the formation of a blood clot.

Haemorrhagic stroke

Haemorrhagic stroke occurs when a blood vessel in your brain leaks or ruptures. Haemorrhages can result from a number of conditions that affect your blood vessels, including uncontrolled high blood pressure (hypertension) and weak spots in your blood vessel walls (aneurysms). There are two types of haemorrhagic stroke:

Intracerebral hemorrhage

In this type of stroke, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging cells. Brain cells beyond the leak are deprived of blood and are also damaged. High blood pressure is the most common cause of this type of haemorrhagic stroke. Over time, high blood pressure can cause small arteries inside your brain to become brittle and susceptible to cracking and ruptures.

Subarachnoid hemorrhage

In this type of stroke, bleeding starts in a large artery on or near the surface of the brain and spills into the space between the surfaces of your brain and your skull. This type of haemorrhage is often signaled by a sudden, severe "thunderclap" headache. This type of stroke is commonly caused by the rupture of an aneurysm, which can develop with age or be genetically inherited. After the haemorrhage, the blood vessels in your brain may widen and narrow erratically (vasospasm), causing brain cell damage by further limiting blood flow to parts of your brain.

Transient ischemic attack (TIA) and stroke

A transient ischemic attack (TIA, or mini-stroke) is a brief episode of symptoms similar to those in a stroke. The cause of a transient ischemic attack is a temporary decrease in blood supply to part of your brain. Most attacks last just a few minutes.

A TIA doesn't leave lasting effects to your brain. Still, if you've had a TIA, it means there's likely a blocked or narrowed artery leading to your brain, putting you at a greater risk of a full-blown stroke that could cause more permanent damage. If you're having a TIA, get emergency medical treatment and make sure your regular physician knows about it.

Risk factors

• Stroke risk factors include:
• A family history of stroke, heart attack or TIA
• Being aged 55 or older
• High blood pressure - a systolic blood pressure of 140 mm of mercury (mm/Hg) or higher, or a diastolic pressure of 90 mm/Hg or higher
• High cholesterol - a total cholesterol level of 200 milligrams per deciliter (mg/dL), or 5.2 mmol/L, or higher
• Cigarette smoking
• Diabetes
• Obesity - a body mass index of 30 or higher
• Cardiovascular disease, including heart failure, a heart defect, heart infection, or abnormal heart rhythm

Complications

Depending on how long the brain suffers a lack of blood flow, a stroke can sometimes cause temporary or permanent disabilities. Stroke complications differ depending on what part of the brain was affected and may include:

• Paralysis or loss of muscle movement. Sometimes, a lack of blood flow to the brain can cause a person to become paralysed on one side of the body, or lose control of certain muscles, such as those on one side of the face. With physical therapy, you may see improvement in muscle movement or paralysis. 
• Difficulty talking or swallowing. A stroke may cause a person to have less control over the way the muscles in the mouth move, making it difficult to talk, swallow or eat. A person may also have difficulty speaking because a stroke has caused aphasia, a condition in which a person has difficulty expressing thoughts through language. Therapy with a speech and language pathologist may improve this disability.
• Memory loss or troubles with understanding. It's common that people who suffer strokes have some memory loss. Others may develop difficulty understanding concepts. This complication may improve with rehabilitation.
• Pain. Some people who have a stroke may have pain, numbness, or other strange sensations in parts of their body affected by stroke.

People who have a stroke may also become withdrawn and less social. They may lose the ability to care for themselves and may need a caretaker to help them with their grooming needs and daily chores after a stroke.

As with any brain injury, the success of treating these complications will vary from person to person.

Source : http://www.mayoclinic.com/health/stroke

The New Straits Times

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