Medical negligence

What is a subarachnoid haemorrhage?

A subarachnoid haemorrhage (SAH) is a form of stroke caused by a sudden bleed over the surface of the brain. It is a serious and life-threatening condition and is classed as a medical emergency.

17 February 2020


A SAH occurs beneath the arachnoid – one of three protective membranes that surround the brain and spinal cord. The blood vessels supplying blood to the brain are contained here and are surrounded by cerebrospinal fluid which acts as a cushion protecting the brain and spine from injury.


The main symptom of a subarachnoid haemorrhage is a sudden and severe headache often described as an intense pain unlike anything experienced previously. Other symptoms can include vomiting, double vision, slurred speech, a stiff neck, sensitivity to light, weakness on one side of the body, seizures, and a loss of consciousness.


In many subarachnoid haemorrhage cases, a weakness in the wall of one of the blood vessels supplying blood to the brain causes a swelling. The resulting build-up of blood pressure causes the swelling to balloon. This is known as an aneurysm. Most SAHs are caused by a brain aneurysm rupturing and bleeding into the surrounding brain tissue.

It is not known exactly why brain aneurysms develop, although age, a family history of the condition and certain lifestyle-related factors such as smoking, having high-blood pressure and excessive alcohol intake are believed to increase the risks.

Other less common SAH causes include having an abnormal tangle of blood vessels or inflamed blood vessels in the brain. Severe head injuries can also cause SAH. These are known as ‘traumatic subarachnoid haemorrhages.’


When someone is believed to have suffered a subarachnoid haemorrhage, they will need to attend hospital to undergo a computed tomography (CT) scan as soon as possible to check for signs of bleeding around the brain. CT scans can produce detailed 3D images of internal organs, blood vessels and bones.

Sometimes a CT scan will fail to detect a SAH. When this happens and a subarachnoid haemorrhage is strongly suspected, patients may need to undergo a ‘lumbar puncture.’ This is a procedure whereby a needle is inserted into their lower spine to extract a sample of cerebrospinal fluid for analysis.

If the results confirm the presence of a SAH, patients may undergo an ‘angiogram’ to determine what kind of treatment is necessary. An angiogram involves guiding a catheter into the blood vessels in the neck that supply blood to the brain. A dye is then injected into the arteries of the brain to enable an outline of the vessels to show up on an x-ray. This helps identify the exact location of the aneurysm.


Medication will usually be given to relieve severe headaches and help prevent complications associated with SAH. These can include what is known as ‘rebleeding’ whereupon a brain aneurysm bursts a second time after having sealed itself. Rebleeding can cause permanent disability and death so it is critical that secondary aneurysms are repaired as soon as possible.

Another serious complication is ‘secondary cerebral ischaemia’ also known as ‘vasopasm.’ This is where blood flow to the brain becomes dangerously restricted, causing brain damage. Medication can be given to reduce the risks of this occurring. Anticonvulsant and antiemetic medication can also be given to prevent seizures and nausea.

Surgery to repair damaged blood vessels, relieve pressure on the brain and prevent rebleeding may be necessary if scans confirm that a SAH was caused by a brain aneurysm. Surgical procedures include either ‘neurosurgical clipping’ or ‘endovascular coiling.’

Neurosurgical clipping is carried out under general anaesthetic and involves making an incision above the eyebrow and removing a section of bone to enable access to the brain. A metal clip is then permanently clamped around the aneurysm to seal it shut and prevent it from growing or rupturing again.

Endovascular coiling is also carried out under general anaesthetic and involves inserting a catheter into an artery near the groin and guiding it via the blood vessels into the head and aneurysm. Platinum coils are then passed into the aneurysm to seal it from the main artery and prevent it from growing or rupturing again.

Expert Opinion

Our medical negligence lawyers frequently act for the families of people who have sadly died after conditions such as aortic aneurysms, subarachnoid haemorrhages and other brain haemorrhages were either missed altogether or diagnosis was delayed.

Emergency departments are an area of the NHS where things can often go wrong. Fractures going unnoticed, for example, are a particularly common occurrence and one that in some cases can lead to serious consequences and even disability for patients.

One recent client tragically died after symptoms that included a pounding headache, vomiting and weakness on one side of his body were repeatedly dismissed by doctors. By the time he was eventually admitted to hospital and diagnosed as having a subarachnoid haemorrhage, it was too late and he suffered a fatal pulmonary embolism.

Although subarachnoid haemorrhage compensation claims are complex, we have particular experience in dealing with these types of claim. It is especially important that your lawyers understand the legal and medical issues arising from brain injuries and that they can provide you with the support you need.

For more information about subarachnoid haemorrhage caused as a result of medical negligence contact us on freephone 0330 107 5007 or contact us online.

All information was correct at the time of publication.

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