Health A to Z
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 strokes in the UK.
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 subarachnoid haemorrhage is a medical emergency. Dial 999 immediately and ask for an ambulance if you, or someone in your care, has these symptoms.
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.
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The majority of subarachnoid haemorrhages are caused by a brain aneurysm bursting. A brain 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:
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".
Read more about the causes of subarachnoid haemorrhages.
Between April 2013 and April 2014, more than 6,000 people were admitted to hospitals in England with a subarachnoid haemorrhage.
Subarachnoid haemorrhages can happen at any age but they're most common in people aged between 45 and 70. 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. Read more about black health issues.
It's not always possible to prevent a subarachnoid haemorrhage, but there are some things you can do to reduce your risk.
The three most effective steps you can take to reduce your chances of having a subarachnoid haemorrhage are:
A subarachnoid haemorrhage can cause both short and long-term complications.
Serious short-term complications can include further bleeding at the site of any aneurysm and brain damage caused by a reduction in blood supply to the brain.
Long-term complications include:
Read more about the complications of a subarachnoid haemorrhage.
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:
Read more about recovering from a subarachnoid haemorrhage.
A subarachnoid haemorrhage is most often caused by a 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 eight out of every 10 subarachnoid haemorrhages happen in this way.
A brain aneurysm doesn't usually cause any symptoms unless it ruptures. However, some people with unruptured aneurysms experience symptoms such as:
It's not known exactly why brain aneurysms develop in some people, although certain risk factors have been identified. These include:
Most brain aneurysms won't rupture but a procedure to prevent subarachnoid haemorrhages is sometimes recommended if they're detected early.
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Less common causes of subarachnoid haemorrhages include:
If you may have a subarachnoid haemorrhage, you'll be referred to hospital to confirm the diagnosis.
A computerised tomography (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.
In some cases, a subarachnoid haemorrhage isn't picked up by a CT scan. If a CT scan is negative, but your symptoms strongly suggest you've had a haemorrhage, a test called a lumbar puncture will usually be carried out.
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.
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:
Both of these tests are carried out in the same way as a regular scan. However, a special dye is injected into a vein (usually in your arm or hand) which highlights 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.
If you're diagnosed with a subarachnoid haemorrhage, or a diagnosis is strongly suspected, you'll usually be transferred to a specialist neurosciences unit.
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).
The treatments you may have are described below.
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 three weeks, until the risk of secondary cerebral ischaemia has passed.
Side effects of nimodipine are uncommon, but can include:
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 that may be used to treat a subarachnoid haemorrhage include:
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 bleeding again may be recommended.
This can be carried out using one of two main techniques. These are described below.
Neurosurgical clipping is carried out under general anaesthetic, meaning you'll be asleep throughout the operation. A cut is made in your scalp (or sometimes just above your eyebrow) and a small flap of bone removed, so the surgeon can access your brain. This type of operation is known as a craniotomy.
When the aneurysm is located, the neurosurgeon (an expert in surgery of the brain and nervous system) will seal it shut using a tiny metal clip that stays permanently clamped on the aneurysm. 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 from growing or rupturing again.
Endovascular coiling is also usually carried out using general anaesthetic. The procedure involves inserting a thin tube called a catheter 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 can't enter it. This means the aneurysm is sealed off from the main artery, preventing it from growing or rupturing again.
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.
However, 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.
If you have a subarachnoid haemorrhage, there's also a risk of developing further problems.
Some of the main complications are described below.
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.
Delayed cerebral ischaemia, or vasospasm, is another serious and common complication of a subarachnoid haemorrhage. This is when 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.
The cause is uncertain, but vasospasm of the arteries inside the brain may be a factor. Vasospasm is when a blood vessel goes into a spasm, causing the vessel to narrow.
There are many treatments that can be used to prevent and treat delayed cerebral iscahemia, including a medication called nimodipine. See treating subarachnoid haemorrhages for more information about nimodipine.
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:
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 clear colourless 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.
There are a number of long-term complications that can affect people after a subarachnoid haemorrhage. These are outlined below.
Around 1 in 20 people who have a subarachnoid haemorrhage develop epilepsy.
This is a condition 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.
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 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:
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. The doctor in charge of your care 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 are another common, long-term complication of a subarachnoid haemorrhage.
These problems can take a number of forms, such as:
These mood disorders can be treated using a combination of:
The time it will take you to recover from a subarachnoid haemorrhage will depend on it's 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 (known as aphasia).
Recovery can be a frustrating process. You may make a lot of progress and then suffer setbacks – you will have good days and bad days.
Feelings of anger, resentment and sadness are common. Talking to other people with similar conditions via support groups 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:
Many of the common after-effects of a subarachnoid haemorrhage, and some tips to help you deal with them, are outlined below.
During the first few months after a subarachnoid haemorrhage, it is normal to feel extremely tired (known as 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 three times a day, can help.
After having a subarachnoid haemorrhage, many people find they have problems getting to sleep (known as 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 are common after a subarachnoid haemorrhage, but they tend to ease over time. They are not as painful as when you had your haemorrhage, and you should be able to control them with over-the-counter painkillers, such as paracetamol.
Drinking plenty of fluids, as well as avoiding alcohol and caffeine, can also reduce the severity and frequency of these headaches.
After having a subarachnoid haemorrhage, 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 are common and usually pass over time.
Following a subarachnoid haemorrhage, 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.
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. However, these changes in the senses are normally temporary and will resolve as the swelling on your brain goes down.
Following 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 will 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.
If you are 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 carer 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.
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 email@example.com.
You can contact Headway, the brain injury association, on 0808 800 2244 (9am to 5pm on weekdays) or email you can email firstname.lastname@example.org.