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What is a Stroke?

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A stroke is a medical emergency that occurs when blood flow to the brain is interrupted. This interruption can happen for two main reasons: a blockage or a rupture of a cerebral artery.

In both cases, the lack of blood flow cuts off the supply of oxygen and nutrients to nerve cells in the affected area, causing them to die within minutes. Without immediate intervention, this can lead to serious and permanent neurological damage.

Stroke explained in first person

Professionals and patients explain how you live with the disease
Stroke | PortalCLÍNIC
Up to 80% of the risk of a stroke may be prevented with health life habits, such as following a healthy diet and regular physical exercise, to avoid obesity and toxic habits.
Stroke explained in first person | ...
It's a complicated disease. You can take months ... years ... to recover, but you go ahead. It is important to lean on the medical team and the people around you. And over all, don't give up.

Why is it so important to act quickly in the case of a stroke?

The brain is a highly specialised organ and is extremely sensitive to lack of oxygen and nutrients. Every second without the adequate blood flow increases the risk of irreversible damage to brain cells (neurons), which raises the chance of suffering neurological sequelae. That’s why stroke is considered a medical emergency. Recognising the signs early and acting quickly can make all the difference, helping to limit brain damage and improving the chances of recovery. 

Recognising the symptoms of a stroke and seeking urgent medical attention is essential for effective treatment.

Difference between an artery and a vein

Arteries and veins are the two main types of blood vessels involved in blood circulation. Arteries carry blood from the heart to the tissues and organs of our body. This blood is rich in oxygen and nutrients, which are essential for cellular function. Veins, on the other hand, carry blood with less oxygen from the tissues and organs back to the heart.

The interruption of blood flow in both types of cerebral vessels can lead to a stroke. However, most strokes are caused by a blockage of the cerebral arteries. When this blockage occurs in a cerebral vein (cerebral venous sinus thrombosis, CVST) it hinders the return of blood from the brain back to the heart, leading to increased pressure in the skull, swelling and brain damage. CVST usually presents with a persistent headache and neurological symptoms similar to those of an arterial stroke (weakness, numbness, speech difficulties, trouble walking or vision problems) and in some cases, it may cause seizures.

Although it is much less common than arterial stroke, CVST is a serious condition that also requires immediate medical attention to prevent severe complications.

Types of Stroke?

  • Blockage of a cerebral artery (ischaemic stroke). It is the most common type of stroke, accounting for 85% of cases. The blockage of the cerebral artery, usually caused by a blood clot or cholesterol plaque (atherosclerosis), disrupts blood flow to the affected part of the brain.
  • Rupture of a brain artery (haemorrhagic stroke). This type of stroke occurs when a cerebral blood vessel bursts and causes bleeding in the brain.

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 used as an umbrella term that encompasses different mechanisms, both ischaemic and haemorrhagic strokes. The term 'stroke' is preferred when referring to this group of conditions, as the other terms described below refer only to specific subtypes of stroke.

A thrombosis is the formation of a blood clot (thrombus) within blood vessels (cerebral artery or vein).

An embolism occurs when a blood clot forms in another part of the body (heart, atherosclerosis plaque) and travels through the bloodstream until it blocks a blood vessel, cutting off circulation. 

Brain bleed is often used colloquially to refer to a brain haemorrhage. In this case, it is caused by a rupture of a blood vessel in the brain, causing blood to leak out and therefore, compressing the brain structures in the affected area.

Although each of them has different causes and mechanisms, they all require urgent treatment to minimize brain damage.

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.

Read more Causes
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Substantiated information by:

Antonia Fernández
Arturo Renú Jornet
Xabier Urra Nuin
Ángel Chamorro Sanchez

Published: 20 February 2018
Updated: 24 July 2025

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.

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