A subarachnoid haemorrhage is most often caused by a burst blood vessel in the brain (a ruptured brain aneurysm).

A brain aneurysm is a bulge in a blood vessel caused by a weakness in the blood vessel wall, usually at a point where the vessel branches off.

As blood passes through the weakened vessel, the pressure causes a small area to bulge outwards like a balloon.

Occasionally, this bulge can burst (rupture), causing bleeding around the brain. Around 8 out of every 10 subarachnoid haemorrhages happen in this way.

A brain aneurysm doesn't usually cause any symptoms unless it ruptures.

But some people with unruptured aneurysms experience symptoms such as:

• sight problems
• pain on one side of the face or around the eye
• persistent headaches

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

These include:

• smoking
• high blood pressure
• excessive alcohol consumption
• a family history of the condition
• severe head injury
• autosomal dominant polycystic kidney disease (ADPKD)

Most brain aneurysms won't rupture but a procedure to prevent subarachnoid haemorrhages is sometimes recommended if they're detected early.

Read more about:

• diagnosing brain aneurysms
• treating brain aneurysms

You'll need to have some tests done in a hospital to confirm if you have a subarachnoid haemorrhage.

A CT scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image.

A CT scan is used to check for signs of a brain haemorrhage. This involves taking a series of X-rays, which a computer then makes into a detailed 3D image.

You may also have a test called a lumbar puncture. A lumbar puncture involves a needle being inserted into the lower part of the spine so a sample of the fluid that surrounds and supports the brain and spinal cord (cerebrospinal fluid) can be taken out. It will then be analysed for signs of bleeding.

Planning treatment

If the results of a CT scan or lumbar puncture confirm you've had a subarachnoid haemorrhage, you'll usually be referred to a specialist neuroscience unit.

Further tests are usually needed to help plan treatment, which may include either:

• computed tomography angiography (CTA) – using a CT scan
• magnetic resonance angiography (MRA) – using an MRI scan

Both of these tests are carried out in the same way as a CT scan. But a special dye is injected into a vein (usually in your arm or hand) to highlight your blood vessels and tissues.

Occasionally, an angiogram may be needed. This involves inserting a thin tube called a catheter into one of your blood vessels (usually in the groin). 

Local anaesthetic is used where the catheter is inserted, so you won't feel any pain. 

Using a series of X-rays displayed on a monitor, the catheter is guided into the blood vessels in the neck that supply blood to the brain.

Once in place, special dye is injected through the catheter and into the arteries of the brain.

This dye casts a shadow on an X-ray, so the outline of the blood vessels can be seen and the exact position of the aneurysm can be identified.

Read more about angiography.

You'll usually be transferred to a specialist neurosciences unit if you are suspected of having a subarachnoid haemorrhage.

These units have a range of equipment and treatments to support many of the body's vital functions, such as breathing, blood pressure and circulation.

In more severe cases, you may be transferred to an intensive care unit (ICU).

Medication

Nimodipine

One of the main complications of a subarachnoid haemorrhage is secondary cerebral ischaemia.

This is where the supply of blood to the brain becomes dangerously reduced, disrupting the normal functions of the brain, causing brain damage.

You'll usually be given a medication called nimodipine to reduce the chances of this happening.

This is normally taken for 3 weeks, until the risk of secondary cerebral ischaemia has passed.

Side effects of nimodipine are uncommon, but can include:

• flushing
• feeling sick
• increased heart rate
• headaches
• a rash

Pain relief

Medication can be effective in relieving the severe headache pain associated with a subarachnoid haemorrhage.

Commonly used pain-relieving medications include morphine and a combination of codeine and paracetamol.

Other medications

Other medications that may be used to treat a subarachnoid haemorrhage include:

• anticonvulsants, such as phenytoin – which may be used to prevent seizures (fits)
• antiemetics, such as promethazine – which can help stop you feeling sick and vomiting

Surgery and procedures

If scans show that the subarachnoid haemorrhage was caused by a brain aneurysm, a procedure to repair the affected blood vessel and prevent the aneurysm from bursting again may be recommended.

This can be carried out using one of 2 main techniques. The type of procedure used will depend on your health and the aneurysm's position. Both are carried out under general anaesthetic, meaning you'll be asleep throughout the operation.

Coiling

A thin tube called a catheter is inserted into an artery in your leg or groin.

The tube is guided through the network of blood vessels into your head and into the aneurysm.

Tiny platinum coils are then passed through the tube and into the aneurysm. Once the aneurysm is full of coils, blood cannot enter it.

This means the aneurysm is sealed off from the main artery, preventing it growing or rupturing again.

Clipping

A cut is made in your scalp (or sometimes just above your eyebrow) and a small flap of bone is removed so the surgeon can access your brain. This type of operation is known as a craniotomy.

When the aneurysm is located, a tiny metal clip is fitted around the base of the aneurysm to seal it shut. After the bone flap has been replaced, the scalp is stitched together.

Over time, the blood vessel lining will heal along where the clip is placed, permanently sealing the aneurysm and preventing it growing or rupturing again.

In some cases surgery may not be advisable. This is sometimes called conservative treatment or management. This is where surgery is considered too risky.

Whichever treatment you have, you will need to be closely monitored for some time to avoid complications.

Coiling versus clipping

Whether clipping or coiling is used depends on things such as the size, location and shape of the aneurysm.

Coiling is often the preferred technique because it has a lower risk of short-term complications such as seizures than clipping, although the long-term benefits over clipping are uncertain.

People who have the coiling procedure usually leave hospital sooner than people who have the clipping procedure, and the overall recovery time can be shorter.

But when these types of surgery are carried out as an emergency procedure, your recovery time and hospital stay depend more on the rupture's severity than the type of surgery used.

A subarachnoid haemorrhage can lead to further problems.

Rebleeding

A potentially serious early complication of a subarachnoid haemorrhage is the brain aneurysm bursting again after it's sealed itself. This is known as rebleeding.

The risk of rebleeding is highest in the few days after the first haemorrhage, and carries a high risk of permanent disability or death. Because of this, aneurysm repair is needed as soon as possible.

For more information about surgical treatment, read about treating subarachnoid haemorrhages.

Vasospasm

Vasospasm (also called delayed cerebral ischaemia) is when a blood vessel goes into a spasm, causing the vessel to narrow.

The supply of blood to the brain becomes dangerously low, disrupting the normal functions of the brain and causing brain damage. It's most common a few days after the first haemorrhage.

Common symptoms are increasing drowsiness, which can lead to a coma, with or without other stroke-like symptoms, such as weakness down one side of the body.

There are many treatments that can be used to prevent and treat vasospasm, including a medication called nimodipine.

See treating subarachnoid haemorrhages for more information about nimodipine.

Hydrocephalus

Hydrocephalus is a build-up of fluid on the brain, which increases pressure and can cause brain damage.

This can cause a wide range of symptoms, including:

• headache
• being sick
• blurred vision
• difficulty walking

Hydrocephalus is common after subarachnoid haemorrhage, as the damage caused by a haemorrhage can disrupt the production and drainage of cerebrospinal fluid (CSF). This can lead to increased amounts of fluid around the brain.

CSF is a fluid that supports and surrounds the brain and spinal cord. A constant supply of new CSF is produced inside the brain, while the old fluid is drained away into blood vessels.

Hydrocephalus may be treated with a lumbar puncture or a temporary tube that's surgically implanted into the brain to drain away the excess fluid.

Read more about treating hydrocephalus.

Long-term complications

There are a number of long-term complications that can affect people after a subarachnoid haemorrhage.

Epilepsy

Epilepsy is where the normal working of the brain is interrupted, causing a person to have repeated fits or seizures.

There are different types of seizure, and symptoms vary. You may lose consciousness, have muscle contractions (your arms and legs twitch and jerk) or your body may shake or become stiff.

Seizures usually last between a few seconds and several minutes before brain activity returns to normal.

In most cases of epilepsy following a subarachnoid haemorrhage, the first seizure occurs in the year after the haemorrhage. The risk of having a seizure goes down over time.

Epilepsy can be treated using anti-epileptic medicines, such as phenytoin or carbamazepine. A neurologist will help decide which treatment you need and how long you need to take it for.

Read more about treating epilepsy.

Cognitive dysfunction

Cognitive dysfunction is when a person experiences difficulties with one or more brain functions, such as memory.

Cognitive dysfunction is a common complication of a subarachnoid haemorrhage, affecting most people to some degree.

Cognitive dysfunction can take a number of forms, such as:

• problems with memory – memories before the haemorrhage are normally not affected, but you may have problems remembering new information or facts
• problems with tasks that require some degree of planning – you may find that even simple tasks, such as making a cup of tea, are difficult and frustrating
• problems with concentration or attention

There are a number of self-care techniques you can use to compensate for any dysfunction.

For example, breaking tasks down into smaller steps and using memory aids (such as notes or a diary) can help.

An occupational therapist can also help make day-to-day activities easier, while a speech and language therapist can help with communication skills.

Your care team can tell you how to access these types of services.

Most cognitive functions improve with time, but problems with memory can be persistent.

Emotional problems

Emotional problems are another common, long-term complication of a subarachnoid haemorrhage.

These problems can take a number of forms, such as:

• depression – feeling very down, hopeless and not getting any real enjoyment out of life
• anxiety disorder – a constant sense of anxiety and dread that something terrible is going to happen
• post-traumatic stress disorder (PTSD) – where a person often relives a previous traumatic event (in this case the haemorrhage) through nightmares and flashbacks, and they may experience feelings of isolation, irritability and guilt

These mood disorders can be treated using a combination of:

• medication – such as antidepressants
• talking therapies – such as cognitive behavioural therapy (CBT)

The time it'll take you to recover from a subarachnoid haemorrhage will depend on its severity.

The location of the haemorrhage will also affect whether you have any associated problems, such as loss of feeling in your arms or legs, or problems understanding speech (aphasia).

Recovery can be a frustrating process. You may make a lot of progress and then suffer setbacks – you'll have good days and bad days.

Feelings of anger, resentment and sadness are common. Talking to other people with similar conditions via support groups, like the Stroke Association can provide help and reassurance.

An assessment from a clinical psychologist can also be helpful.

There are many specialists who may be involved in your recovery, including:

• rehabilitation specialists – doctors specialising in recovery from a brain injury
• physiotherapists – specialists in certain techniques, such as exercises and massage, that can help with movement problems
• speech and language therapists – specialists who recognise and help treat communication problems
• occupational therapists – specialists who identify problems you may have in everyday life, such as getting dressed, and can help you work out practical solutions

Common problems

Extreme tiredness

During the first few months after a subarachnoid haemorrhage, it's normal to feel extremely tired (fatigue).

Even simple tasks, such as going to the shops, can leave you feeling exhausted.

Taking regular short breaks of about 20 to 30 minutes in a relaxing environment, ideally at least 3 times a day, can help.

Problems sleeping

Many people find they have problems getting to sleep (insomnia), or they can only sleep for short periods.

Having a set daily routine, where you get up and go to bed at the same time each day, can also help. You should also set time aside for relaxation breaks.

If you go back to work, you could talk to your employer about having extra time for breaks.

For more advice, read 10 tips to beat insomnia.

Headaches

Headaches are common after a subarachnoid haemorrhage, but they tend to ease over time.

They're not as painful as when you had your haemorrhage, and you should be able to control them with painkillers such as paracetamol which you can buy from a pharmacy or supermarket.

Drinking plenty of fluids, as well as avoiding alcohol and caffeine, can also reduce the severity and frequency of these headaches.

Unusual sensations

Some people experience strange or unusual sensations in their brain.

These can be difficult to describe, but some people have said that they feel "tickly" or like somebody is pouring water across their brain.

Nobody is sure exactly why these strange sensations occur, but they're common and usually pass over time.

Loss of feeling or movement

Some people experience a loss of movement and feeling in their arms or legs. This can range from a slight weakness to a complete loss of power.

You may also have problems distinguishing between hot and cold, so be careful when taking a bath or shower.

A training and exercise plan carried out under the supervision of a physiotherapist can help restore feeling and movement to affected limbs.

Changes in senses

Many people experience changes to their sense of smell and taste after they have had a subarachnoid haemorrhage. The senses can be heightened or reduced.

You may find that your favourite food now tastes disgusting, while something you hated now tastes delicious.

But these changes in the senses are normally temporary and will resolve as the swelling on your brain goes down.

Vision

After a brain injury, problems with your vision – such as blurring, blind spots, black spots and double vision – are common.

Your vision will be tested before you leave hospital and, if necessary, you'll be referred to an ophthalmologist (a doctor who specialises in the care of the eye) for further tests and treatment.

In most cases, vision problems improve gradually over a few months.

Driving

You must tell the DVLA if you've had a subarachnoid haemorrhage.

You'll need to avoid driving until you have heard back from the DVLA. The DVLA will decide when you can drive again. It can vary from several weeks to months.

Find out more on GOV.UK.

Caring for someone who has had a brain haemorrhage

If you're caring for someone recovering from a subarachnoid haemorrhage, you may find it a challenging prospect.

They can often have complex needs and engage in challenging and sometimes upsetting behaviour.

You may find it useful to visit the care and support section of this website, which contains a range of useful information, such as a practical guide to caring, money and legal advice and looking after your own wellbeing.

Support groups

There are a number of support groups that can offer information and advice for people who have had a brain haemorrhage, and their carers.

You can contact the Stroke Association helpline on 0303 3033 100 (9am to 5pm on weekdays) or you can email info@stroke.org.uk.

You can contact Headway, the brain injury association, on 0808 800 2244 (9am to 5pm on weekdays) or email you can email helpline@headway.org.uk.