The term stroke, derived from the Latin word ictus meaning ‘a blow’, is used to describe the consequences when an area of the brain suffers a sudden interruption in blood flow (ischaemic stroke, 85% of cases) or a burst artery or vein (haemorrhagic stroke, 15% of cases).
If part of the brain receives poor blood flow its function may be temporarily or permanently changed. Other common names for stroke include brain haemorrhage, embolism, cerebral thrombosis and apoplexy.
Difference between an artery and a vein
Arteries are the blood vessels that carry blood from the heart to the body’s tissues, whereas the veins are the vessels which then return the blood to the heart. While a stroke may be caused by the obstruction or rupture of either type of blood vessel, the majority are the result of a blocked artery.
Obstruction of an intracranial vein (cerebral venous thrombosis) can block the blood’s return to the heart, leading to inflammation and brain damage. A blocked cerebral vein typically manifests as headache plus other symptoms similar to those observed for arterial strokes (weakness or numbness, difficulty talking or maintaining balance, visual disturbances), and occasionally seizures.
Types of Stroke?
There are two types of stroke, defined by the mechanism:
Ischaemic strokes (or cerebral infarctions) are due to obstructed blood flow.
Haemorrhagic strokes (or cerebral haemorrhage) occur when a vessel ruptures and bleeds into the brain, which compresses surrounding central nervous system structures.
Patients presenting similar symptoms may have suffered a stroke via different mechanisms. Identifying the cause of the stroke is of paramount importance as it represents the treatment determining factor both in the acute phase and in the therapeutic strategy to prevent a recurrence.
Difference between a stroke, thrombosis, an embolism and effusion
The term stroke is used to define the group of diseases that cause sudden neurological deficits because of a reduced blood supply reaching nervous system structures. It is better to use the word stroke rather than the other terms because they only describe different types of stroke.
Thrombosis is the formation of a clot inside any blood vessel, this may lead to a stroke if the clot forms inside a cerebral artery or vein.
Embolism refers to a blood vessel obstructed by a clot that formed in another part of the circulatory system, for example, in the heart or on an atherosclerotic plaque in a proximal artery.
Effusion relates to a brain haemorrhage where the main problem is a burst blood vessel bleeding into and compressing the surrounding brain structures
How many people does it affect?
One in six people will suffer a stroke during their lifetime. The Spanish population suffers a stroke every six minutes, leading to the death of one patient every 14 minutes. Stroke is the second most common cause of death worldwide. It results in over 6 million deaths per year and in Spain it represents the leading cause of death in women.
Stroke is the main cause of physical disability in adults and the second cause of cognitive impairment. In fact it is responsible for more cases of disability than all other neurological diseases combined. For these reasons, the direct healthcare costs of stroke in industrialised countries are already very high and predicted to increase in coming years due to an ageing population.