Stroke is a type of cardiovascular disease. It affects the arteries leading to and within the brain. A stroke occurs when a blood vessel which carries oxygen and nutrients to the brain is either blocked by a clot or bursts. When that happens, part of the brain is deprived of the oxygenated blood, so it starts to die.

Types of strokes:
Most strokes occur when a blood clot blocks one of the arteries (blood vessels) that carries blood to the brain. This type of stroke is called an ischaemic stroke.
Transient ischaemic attack (TIA) or 'mini-stroke' is a short-term stroke that lasts for less than 24 hours. The oxygen supply to the brain is quickly restored and symptoms disappear. A transient stroke needs prompt medical attention because it indicates a serious risk of a major stroke.
Cerebral thrombosis is when a blood clot (thrombus) forms in an artery that supplies blood to the brain. Blood vessels that are furred up with fatty deposits (atheroma) make a blockage more likely. The clot prevents blood flowing to the brain and cells are starved of oxygen.
Cerebral embolism is a blood clot that forms elsewhere in the body before travelling through the blood vessels and lodging in the brain. In the brain, it starve cells of oxygen. An irregular heartbeat or recent heart attack may make you prone to forming blood clots.
Cerebral haemorrhage is when a blood vessel bursts inside the brain and bleeds (haemorrhages). With a haemorrhage, blood seeps into the brain tissue and causes extra damage.

Immediate treatment

In hospital, brain scans are needed to find out what type of stroke you've had. If a blood clot is the cause, medication to dissolve the clot  may be used, but this must be given within three hours of the stroke. Anti-clotting medication such as aspirin may also be given to stop the stroke from getting worse.Anti-clotting medication is not given in strokes caused by hemorrhaging because it will make the bleeding worse.Other treatment includes:tests on key functions like swallowing and movement and checks on oxygen, glucose and blood pressure levelsThe types and degrees of disability that follow a stroke will depend upon which area of the brain is damaged. Stroke damage in the brain can affect the entire body, resulting in mild to severe disabilities. Generally, stroke can cause five types of disabilities, which include: paralysis or problems controlling movement, sensory disturbances (including pain) problems using or understanding language, problems with thinking and memory and emotional disturbances.

Diagnosing stroke
There are variety of ways to determine what kind of stroke has occurred, its location and how much damage the stroke has caused. Some of the techniques that are commonly used are: CT Scan - This technique is usually the first test done when a patient comes to a hospital emergency room with stroke symptoms.Arteriography - This is an X-ray of the carotid artery taken when a special dye is injected.Magnetic Resonance Imaging (MRI) - This device uses magnetic fields to detect subtle changes in brain tissue. MRI is useful when the stroke involves small blood vessels.Magnetic Resonance Angiography - Brain surgeons use this technique to detect a blockage of the brain and to map the blood flow in the skull. It gives an accurate picture of cerebral blood vessels.Doppler Ultrasound - This is a painless, noninvasive test in which waves of sound above the range of human hearing are sent into the neck. It is fast, painless and risk-free but is not as accurate as an Arteriography. Carotid Ultrasound - This test is conducted without entering the body and it evaluates the blood flow of the carotid arteries.. This helps doctors determine how narrow an artery has become.