Stroke
A stroke is a life threatening medical emergency that occurs when the blood supply to one part of the brain is cut-off. This cut-off can be due to a blood clot or a burst blood vessel. The person having the stroke may lose control over their movement, perception, and speech. They may also lose consciousness. Symptoms of a stroke may also include sudden numbness, tingling, weakness, loss of movement in face, arm, or leg especially on only one side of your body.
A blood clot near the brain causes a stroke called a ischaemic stroke. This type of stroke is triggered by a thrombus, which is a stationary clot that forms in the blood vessel, or an embolus, which is a clot that travels through the bloodstream and becomes lodged in a vessel. This stroke is sometimes followed by a transient ischaemic attack (TIA), which are episodes of inadequate blood flow that may cause these symptoms, Sudden physical weakness, an inability to speak, double vision, and dizziness. These symptoms may resolve within 24 hours, but these may be signs of an impending stroke.
The second type of stroke is a hemorrhagic stroke, or bleeding stroke. This occurs when a brain aneurysm ruptures, or when a weakened or inflamed blood vessel in the brain starts to leak. As blood flows to the brain, there is a build-up of pressure that may kill the tissue or destroy brain cells by impeding normal circulation and oxygen supply to the affected region. This will produce excruciating headaches, which is sometimes followed by a loss of consciousness. Risk factors for a stroke include high blood pressure, heart disease or high cholesterol levels, obesity, abuse of stimulant drugs, smoking, heavy drinking, or use of oral contraceptives.
source: http://www.webmd.com/stroke/tc/stroke-topic-overview
