A stroke, or cerebrovascular accident, is an interruption of the blood flow in a part of the brain.
It happens after the obstruction or the rupture of a blood vessel, and kills the nerve cells, after a lack of oxygen and nutritive elements for them to work properly.

There are many types of stroke

Embolic stroke: A blood clot forms in the circulatory system – for example following a heart disease or a surgery, and can position itself in one artery of the brain, preventing blood circulation.
Thrombotic or ischaemic stroke: This happens when an artery is gradually blocked by a deposit in the internal wall. Ischemia is not temporary.
Haemorrhagic stroke: Often triggered by the rupture of a cerebral artery during an hypertensive crisis. In some cases, that artery breaks open because it is malformed (aneurism or angioma).
Arterial spams: A cerebral artery may contract and momentarily prevent blood flow. If the spasm lasts too long, cells without blood can be destroyed. This type of stroke is less common.

Source: Ministère de la Santé des Services Sociaux

Consequences of a stroke
They vary from one person to the other. Its gravity depends on the type of stroke as well as which hemisphere of the brain the stroke happened.
The bigger the oxygen-deprived zone is; the consequences may be more important. Certain persons will be aphasic and have memory problems. They might also be affected by a more or less important paralysis.

Aphasia is a communication problem caused by a brain injury either following a cerebrovascular accident, a head injury or a brain tumor.

The capacity to speak, understand, read or write are lessened or lost while intelligence is intact.

The affected person might:

• search for words
• not know how to read
• not know how to write
• not understand the meaning of words
• answer with yes or no

Aphasia is a communication disorder affecting a person and people around them.