What is a stroke?

Un stroke or stroke, is a failure in the circulation of the blood that affects a larger or smaller area of ​​the brain. It occurs as a result of blockage or rupture of a blood vessel and causes the death of nerve cells, which are deprived of oxygen and nutrients essential for their functions. In most people, there are no early warning signs of a seizure. However, several risk factors can be monitored.

To read: the signs of stroke and its symptoms

Strokes have very variable consequences. More than half of people suffer from it. About 1 in 10 people recover completely.

The severity of sequelae depends on the area of ​​the brain affected and the functions it controls. The larger the region deprived of oxygen, the greater the risk of the sequelae. Following a stroke, some people will have difficulty speaking or writing (aphasia) and memory problems. They may also be suffering from paralysis more or less important of the body.

Signs of stroke, a medical emergency

When nerve cells are deprived of oxygen, even for a few minutes, they die; they will not regenerate. Also, the shorter the time between stroke and medical treatment, the lower the risk of serious sequelae.

Regardless of the damage caused by oxygen deprivation, the brain has some ability to adapt. Sometimes healthy nerve cells can take over from dead cells if they are stimulated by various exercises.

Causes

Atherosclerosis, the formation of lipid plaques on the walls of blood vessels, is one of the main causes of stroke. High blood pressure is also a major risk factor. Over time, the abnormal pressure exerted by the blood on the walls of the blood vessels can cause them to rupture. A ruptured artery in the brain may be facilitated by the presence of a aneurism. Aneurysm is swelling of a small section of an artery, due to weakness in the wall.

It is not always possible to determine the exact cause of a stroke. It is important, however, that doctors look for it with various tests to reduce the risk of a recurrence.

Prevalence

Thanks to advances in prevention, the prevalence of stroke has declined dramatically in recent decades. Since the 1990s, however, it seems to be stabilizing.

Even today, in Canada, more than 50 people suffer a stroke each year and approximately 000 die from it. Although strokes are rarer than heart attacks, they are still the third leading cause of death in the country and are a major factor in disability.

Three quarters of strokes occur in people aged 65 and over. In Canada and North America, in general, they affect women more than men. Young children can also suffer from it, but it rarely happens.

Types

There are 3 types of stroke: the first 2 are caused by blockage of a cerebral artery (ischemic attack). They are the most common and represent about 80% of strokes. The third is caused by a brain hemorrhage (hemorrhagic accident):

• Cerebral thrombosis. It represents 40% to 50% of cases. It occurs when a clot blood forms in a cerebral artery, on a lipid plaque (atherosclerosis);
• Cerebral embolism. It represents about 30% of cases. As with thrombosis, a cerebral artery is blocked. However, here the clot that is blocking the artery has formed elsewhere and has been carried by the bloodstream. It often originates from the heart or a carotid artery (in the neck);
• Cerebral hemorrhage. It accounts for about 20% of cases, but it is the most serious form of stroke. Often caused by long-standing hypertension, it can also result from a ruptured artery in the brain, where there is a aneurism.

  In addition to depriving part of the brain of oxygen, the hemorrhage destroys other cells by putting pressure on the tissues. It can occur in the center or the periphery of the brain, just below the cranial envelope.

  Other, more rare, causes of brain hemorrhages include hypertensive attacks, hemorrhage into a brain tumor, and blood clotting problems.

It may happen that the obstruction of a cerebral artery is only temporary and that it resolves naturally, without leaving any sequelae. We call this phenomenon transient ischemic attack (AIT) or mini stroke. The diagnosis is confirmed by an MRI. The symptoms are the same as those of a “real” stroke, but they go away in less than an hour. A mini-stroke is a red flag to be taken seriously: it can be followed by a sometimes more serious stroke over the next 48 hours. It is therefore important to consult a doctor as soon as possible.