When speed is vital

STROKE is dreaded by everyone. It is defined as a sudden loss of nerve function as a result of inadequate blood flow to the brain. Stroke is about "block" or "bleed" in most cases. About 85 per cent of strokes are due to blockage of blood supply and 15 per cent due to bleeding in the brain.

Interruption of blood supply to the brain may be due to narrowing of the brain arteries or obstruction of blood flow from a distant source such as a blood clot from the heart or cholesterol "debris" from the ruptured lining of arterial walls travelling to the brain arteries.

Spontaneous bleeding in the brain can be due to uncontrolled high blood pressure, abnormal blood vessels, drug-induced thinning of the blood, or ruptured arteries due to congenital swelling of an artery. The least common category of stroke causation is clotting of the veins in the brain.