Hypertension is the major risk factor for stroke, so it is advisable to monitor blood pressure regularly and consult a physician if blood pressure is above 140 max or above 90 min during several resting bouts.
The causes of stroke
In 85% of cases, stroke is the result of a clogged cerebral artery that stops blood flow. It’s called ischemic stroke. The main cause is a build-up of cholesterol deposits on the walls of the vessels, which constrict the diameter of the artery and promote its obstruction. This shrinkage, called atherosclerosis, is sometimes localized in the brain, but it can also happen that a fragment of a cholesterol deposit, present outside of it, breaks off and migrates through the bloodstream into a cerebral artery.
In 15% of cases, stroke is considered hemorrhagic, that is, it is caused by the rupture of a cerebral artery weakened by hypertension (a major cause), malformation or treatment. The rupture of the artery then leads to bleeding in the brain.
In an ischemic stroke, the cells, especially the neurons, in the affected area of the brain are hypoxic, that is, they no longer receive enough oxygen and sugar, which are essential for their survival and are normally supplied by the bloodstream.
When this situation is prolonged, the cells die, causing the loss of brain functions associated with the affected areas. Initially, cell death occurs only in a small area close to the obstruction. Around this perimeter, there is a “penumbral zone” where the damage caused is reversible if blood circulation is restored quickly, that is, within 6 hours of the first signs of stroke.
Blocking circulation in a cerebral artery kills 1.9 million neurons every minute (total neurons: about 100 billion).
