Subarachnoid Haemorrhage:

This page is intended as a patient/relative information source only. It is not a substitute for professional medical advice.

What Is Subarachnoid Haemorrhage?

Subarachnoid haemorrhage is the term used to describe when there is bleeding between two of the layers that line the brain (the subarachnoid space). The blood is often found as a layer that covers all of the brain, rather than a single, big clot, although sometimes big clots do occur. In Leeds, we see between 150 and 180 cases per year (around three per week).

A CT Scan of the brain showing subarachnoid haemorrhage. The light areas indicated represent blood

What Causes Subarachnoid Haemorrhage?

The most common reason to have a subarachnoid haemorrhage is trauma (a head injury) but it can happen without any history of injury (known as atraumatic or spontaneous subarachnoid haemorrhage). Head injuries are discussed here. The rest of this article will discuss spontaneous subarachnoid haemorrhage.

The most common reason for spontaneous subarachnoid haemorrhage to happen is rupture of an aneurysm on an artery in the brain. Aneurysms are areas of weakness of the artery walls that, with time can bulge and eventually tear (known as rupturing) to cause the subarachnoid haemorrhage. The reasons that someone develops an aneurysm aren’t fully understood but we do know that they are much more common in people who smoke and people who have high blood pressure. There are also some types of aneurysms that have a genetic element (they seem to run in families) and some that are associated with other medical conditions.

AVM is short for arteriovenous malformation and is the technical term used to describe an abnormal arrangement of blood vessels. AVMs can occur throughout the body but in the brain, they also carry a risk of rupturing and causing a subarachnoid haemorrhage.

Uncertain Cause
Sometimes it is unclear why a subarachnoid haemorrhage has happened. People who fall into this group tend to do well and most do not have problems in the future once they are well enough to go home.

How Is Subarachnoid Haemorrhage Diagnosed?

People with subarachnoid haemorrhage often complain of a sudden, severe headache – “like being hit around the head with a baseball bat”. Sometimes they might also feel or be sick, have a stiff neck, photophobia (not liking bright lights), be confused or agitated or even unconscious.

A subarachnoid haemorrhage can usually be seen on a CT scan of the head but not always. If a doctor thinks that a subarachnoid haemorrhage is likely but the CT scan is normal, they may decide to do a lumbar puncture (putting a small needle into the back to get a sample of spinal fluid) to test the spinal fluid for blood.

If subarachnoid blood is seen on a CT scan, doctors need to work out why this has happened. Usually this will involve another CT of the head but this time some dye (contrast) is injected to help us to see the blood vessels more clearly – this test is called a CT angiogram.

Sometimes, the CT angiogram does not give us enough information and more tests are needed, such a catheter angiogram.

A catheter angiogram is a special test where a small cut is made in the groin and a wire is fed up inside the arteries of the body to guide a catheter (plastic tube) up into the neck, which is then used to squirt dye into the blood vessels in the head while a machine takes X-ray pictures. A catheter angiogram is a very good test to look for (and to rule out) aneurysms in the head.

How Is Subarachnoid Haemorrhage Treated?

Usually, the bleeding has stopped by the time the patient reaches hospital and in most cases immediate surgery is not needed. A lot of the treatment for subarachnoid haemorrhage is focussed on keeping people well while their body tries to get over the bleeding that has already happened.

Unfortunately, we know that if a person has a subarachnoid haemorrhage from an aneurysm there is a high risk that it will bleed again in the future and one of the main focuses of treatment is to secure an aneurysm so that it is no longer a risk to the patient.

If an aneurysm is seen on the CT-angiogram or catheter angiogram, there are two ways of dealing with it: coiling and clipping.

Coiling of an aneurysm is a procedure that is performed by the radiology doctors. It is a bit like a catheter angiogram; the patient is put to sleep before a small cut is made in the groin and a wire is used to guide a plastic tube (catheter) up into the neck. From here, the radiologists are able to push tiny platinum coils into the aneurysm until it is filled with coils and blood can no longer get into the aneurysm.

An example of an aneurysm filled with multiple coils

Clipping of an aneurysm is a procedure that is performed by the neurosurgery doctors. It is an operation that involves being put to sleep before some of the hair is shaved and a cut made in the head. A small trap door is made in the skull bone to allow access to the brain (this is called a craniotomy) and the blood vessels are followed until the aneurysm is seen and a metal clip can be put across it so that blood can no longer get into the aneurysm.

An example of an aneurysm clip. [Image copyright Mr Jake Timothy]

Both of these treatments are available at Leeds. There are lots of factors that affect which technique is best for each patient and these would be discussed on an individual basis.

What Is The Outlook?

Subarachnoid haemorrhage is a very serious condition and the outcomes can range from very good to very grave. It is not possible to predict who will do well and who will not do so well – neurosurgery is a very unpredictable science! There are lots of potential complications from subarachnoid haemorrhage but the team in Leeds are well-equipped to deal with these if and when they occur.

More Support & Information

We now have a clinical nurse specialist who will provide support to families and patients who have been affected by subarachnoid haemorrhage, and indeed all neurovascular conditions. For further information, please see this page.

Potential Complications

Because the brain controls the rest of the body, there can be lots of different complications affecting almost any part of someone's health from their breathing to their balance of salts in the blood. One of the most common complications that we see in subarachnoid haemorrhage is called vasospasm. Vasospasm is when the blood vessels that supply the brain become irritated by the blood from the subarachnoid haemorrhage and close up; this can lead to problems with people's consciousness, confusion or even stroke-like problems. There are lots of different ways to treat vasospasm; some of which are medicines that can be given on the ward and some of which involve specific procedures.

Most patients who are admitted with a subarachnoid haemorrhage will be initially treated on our intensive care unit or our high dependency unit, where they can be closely monitored.


Page Author: Mr Ian Anderson, February 2011

Website created and edited by Ian Anderson