A stroke is a “brain attack”. It can happen to anyone at any time. It occurs when blood flow to an area of brain is cut off. When this happens, brain cells are deprived of oxygen and begin to die. When brain cells die during a stroke, abilities controlled by that area of the brain such as memory and muscle control are lost. How a person is affected by their stroke depends on where the stroke occurs in the brain and how much the brain is damaged.
For example, someone who had a small stroke may only have minor problems such as temporary weakness of an arm or leg. People who have larger strokes may be permanently paralyzed on one side of their body or lose their ability to speak. Some people recover completely from strokes, but generally more than 2/3 of survivors will have some type of disability.
Different Forms of Strokes:
Ischemic stroke is the most common form of stroke, accounting for around 85% of strokes. This type of stroke is caused by blockages or narrowing of the arteries that provide blood to the brain, resulting in ischemia – severely reduced blood flow.
These blockages are often caused by blood clots, which can form either in the arteries connecting to the brain, or in other blood vessels before being swept through the bloodstream and into narrower arteries within the brain. Clots can be caused by fatty deposits within the arteries called plaque. Hypertension can lead to rupturing of blood vessels and hemorrhagic stroke.
Hemorrhagic stroke are caused by arteries in the brain either leaking blood or bursting open. The leaked blood puts pressure on brain cells and damages them. Blood vessels can burst or spill blood in the middle of the brain or near the surface of the brain, sending blood into the space between the brain and the skull. The ruptures can be caused by conditions such as hypertension, , trauma, blood-thinning medications and aneurysms (weaknesses in blood vessel walls).
- Intracerebral hemorrhage is the most common type of hemorrhagic stroke and occurs when brain tissue is flooded with blood after an artery in the brain bursts.
- Subarachnoid hemorrhage is the second type of hemorrhagic stroke and is less common. In this type of stroke, bleeding occurs in the subarachnoid space – the area between the brain and the thin tissues that cover it.
Transient ischemic attack (TIA)
Transient ischemic attacks are different from the aforementioned kinds of stroke because the flow of blood to the brain is only briefly interrupted. These are similar to ischemic strokes in that they are often caused by blood clots or other debris.
TIAs should be regarded as medical emergencies just like the other kinds of stroke, even if the blockage of the artery is temporary. They serve as warning signs for future strokes and indicate that there is a partially blocked artery or clot source in the heart.