Introduction

A subarachnoid haemorrhage is an uncommon type of stroke caused by bleeding on the surface of the brain. It's a very serious condition and can be fatal.

Subarachnoid haemorrhages account for around 1 in every 20 Heat exhaustion and heatstroke in the UK.

Symptoms of a subarachnoid haemorrhage

There are usually no warning signs but a subarachnoid haemorrhage sometimes happens during physical effort or straining such as coughing, going to the toilet, lifting something heavy or having sex.

The main symptoms of a subarachnoid haemorrhage include:

• a sudden agonising headache which is often described as being similar to a sudden hit on the head, resulting in a blinding pain unlike anything experienced before
• a stiff neck
• feeling and being sick
• sensitivity to light (photophobia)
• blurred or double vision
• stroke-like symptoms such as slurred speech and weakness on one side of the body
• loss of consciousness or convulsions (uncontrollable shaking)

A subarachnoid haemorrhage is a medical emergency. Dial 999 immediately and ask for anambulance if you, or someone in your care, has these symptoms.

How a subarachnoid haemorrhage is treated

A person with a suspected subarachnoid haemorrhage needs a computerised tomography (CT) scan in hospital to check for signs of bleeding around the brain.

If a diagnosis of subarachnoid haemorrhage is confirmed or strongly suspected, you're likely to be transferred to a specialist neurosciences unit.

Medication will usually be given to help prevent short-term complications (see below) and a procedure to repair the source of the bleeding may be carried out.

Abrain aneurysm is a bulge in a blood vessel, caused by a weakness in the blood vessel wall.

It's not known exactly why brain aneurysms develop in some people. However, certain risk factors have been identified, including:

• smoking
• high blood pressure
• excessive alcohol consumption

Less common causes of subarachnoid haemorrhages include having abnormally developed blood vessels and inflammation of blood vessels in the brain.

Severe head injuries often cause subarachnoid bleeding, but this is a separate problem known as a "traumatic subarachnoid haemorrhage".

Slightly more women are affected than men.

Subarachnoid haemorrhages are also more common in black people compared to other ethnic groups. This could be because black people are more likely to have high blood pressure.

Serious short-term complications caninclude further bleeding at the site ofanyaneurysm and brain damage caused by a reduction in blood supply to the brain.

Long-term complications include:

• epilepsy where a person has repeated seizures (fits)
• problems with certain mental functions, such as memory, planning and concentration
• changes in mood, such as depression

Outlook

Although the outlook for subarachnoid haemorrhage has improved in the last few decades, around half of all cases are fatal, and people who survive can be left with long-term problems.

Recovering after a subarachnoid haemorrhage can also be a slow and frustrating process, and it's common to have problems such as:

• extreme tiredness
• headaches
• problems sleeping

Haemorrhage

To haemorrhage means to bleed or lose blood.

Blood

Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Blood vessels

Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Tissue

Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.