Cardiovascular accident (CVA) is a disease defined as a sudden neurological deficit (e.g. weakness, loss of sensation or other) due to a vascular cause. The deficit must last for longer than 24 hours and is of sudden onset. A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue (cerebral infarction) and causing sudden symptoms.
Pathophysiologically, CVA can be classified into two processes:
- Ischaemic (85%): can be due to a thrombus (a clot forming in one of the blood vessels supplying the brain); or due to an embolus – a clot which travels from another site (usually the heart) to block off one of the arteries in the brain.
- Haemorrhagic (15%): this is due to rupture of one of the arteries in the brain – usually due to an aneurysm (an outpouching of an artery – causing a point of weakness).