Subarachnoid Haemorrhage

A subarachnoid haemorrhage is a rare but life-threatening type of stroke that occurs when bleeding happens in the space between the brain and the tissues covering it, often causing a sudden, extremely severe headache that people describe as the worst of their lives.

Table of contents

• What is Subarachnoid Haemorrhage
• Warning Signs and Symptoms
• Main Causes and Risk Factors
• How It Is Diagnosed
• Treatment Options
• Outlook and Recovery
• Living With the Condition

What is Subarachnoid Haemorrhage

A subarachnoid haemorrhage (SAH) is bleeding that occurs in the space between your brain and the thin tissues that cover and protect it^[1]. This space is called the subarachnoid space, and it normally contains fluid that cushions the brain and spinal cord^[2].

• Brain
• Meninges (brain covering tissues)
• Subarachnoid space
• Blood vessels of the brain

Your brain has three membrane layers that lie between your skull and your brain tissue. The outermost layer is called the dura mater, the middle layer is the arachnoid, and the layer closest to your brain is the pia mater. When bleeding occurs below the arachnoid layer, it causes a subarachnoid haemorrhage^[3].

When blood spills into this space, it builds up and presses on the brain^[19]. The increased pressure can interfere with brain function and cause serious damage. This is a medical emergency that requires immediate treatment^[1].

Approximately 10 to 14 out of 100,000 people per year experience a subarachnoid haemorrhage in the United States^[3]. In the United Kingdom, the incidence is approximately 8 per 100,000 population, peaking at 50 to 60 years of age, and it is 1.6 times more common in women than men^[13].

Warning Signs and Symptoms

The most common symptom of a subarachnoid haemorrhage is a very sudden, very severe headache that starts in a split second^[1]. This is often called a “thunderclap headache” because it comes on suddenly, like a clap of thunder^[3]. People who have experienced it often describe it as the worst headache of their life, unlike any headache they have ever experienced^[2].

Along with the sudden, severe headache, other symptoms may include^[1][3]:

• Nausea and vomiting
• Stiff neck or neck pain
• Changes in vision or sensitivity to bright light
• Brief loss of consciousness or fainting
• Decreased consciousness and alertness
• Sudden weakness
• Mood and personality changes, including confusion and irritability
• Dizziness
• Having a seizure (fit) or shaking uncontrollably
• Drooping on one side of the face, slurred speech, or weakness on one side of the body

A subarachnoid haemorrhage can happen at any time, but it may be more likely when you are doing something like coughing, going to the toilet, lifting something heavy, or having sex^[6].

If you or someone you are with experiences a thunderclap headache or any of these symptoms, call emergency services immediately. Do not drive yourself to the hospital^[6]. This is a life-threatening medical emergency that needs treatment right away^[1].

Main Causes and Risk Factors

A subarachnoid haemorrhage most commonly affects people who have a bulge in a blood vessel in their brain, called a brain aneurysm^[6]. Most subarachnoid haemorrhages occur when an irregular bulge in a blood vessel, known as an aneurysm, bursts in the brain^[1]. About 80 to 85 percent of spontaneous subarachnoid haemorrhages are caused by the rupture of an intracranial aneurysm^[4][2].

There is not always an obvious reason why you may have a brain aneurysm. Some people have them from birth, while others may develop them later. You may be more likely to have a brain aneurysm if other people in your family have them^[6]. Most brain aneurysms do not cause problems, but if one bursts it causes bleeding in the subarachnoid space^[6].

Most aneurysms are found in the front part of the blood vessel system of the brain. Aneurysms in the back part are less frequent, accounting for only 12 percent of intracranial aneurysms^[13].

Subarachnoid haemorrhages can also be caused by^[6][1]:

• A severe head injury
• A problem with the way the blood vessels in your brain have formed, called an arteriovenous malformation (AVM)
• Other health conditions, including conditions that affect the blood vessels

An arteriovenous malformation is a tangled, abnormal mesh of blood vessels that connects an artery and a vein in the brain. These form accidentally before birth and can appear in several generations of the same family. They are more common in men^[5].

Risk factors that make it more likely that you will experience subarachnoid haemorrhage include^[3][13]:

• An unruptured aneurysm in your brain or elsewhere in your body
• History of a previously ruptured brain aneurysm
• Cigarette smoking
• High blood pressure (hypertension)
• Certain connective tissue conditions such as fibromuscular dysplasia, Ehlers-Danlos syndrome, and Marfan’s syndrome
• History of polycystic kidney disease
• Neurofibromatosis type 1
• Cocaine and/or methamphetamine use
• Excessive alcohol consumption
• Use of blood thinners, such as warfarin
• A strong family history of aneurysms

Subarachnoid haemorrhage can happen to anyone, but it most commonly affects people between the ages of 40 and 60^[3]. Among older people, it most commonly happens to those who have fallen and hit their heads. Among younger people, the most common injury leading to subarachnoid haemorrhage is vehicle crashes^[3].

How It Is Diagnosed

If you have a subarachnoid haemorrhage, you will be ill enough that you need to be evaluated in an emergency room^[5]. The doctor will perform a physical examination and order tests to confirm the diagnosis and find the cause of the bleeding.

To diagnose a subarachnoid haemorrhage, you may need the following tests^[8]:

CT scan (computed tomography scan): This imaging test is very effective at detecting bleeding in the brain. A CT scan creates a three-dimensional image of your body generated by a machine that moves around you^[8]. Your doctor may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram^[8].

MRI (magnetic resonance imaging): This imaging test can also detect bleeding in the brain. An MRI scan may show signs of a subarachnoid haemorrhage in rare cases when it is not detected by a CT scan^[8]. Your doctor might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram^[8].

Cerebral angiography: You may have this test to get more detailed images. A long, thin tube called a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging^[8].

Lumbar puncture (spinal tap): For some people with an aneurysm that caused a subarachnoid haemorrhage, the bleeding may not appear on initial imaging. If this happens, you may need a lumbar puncture. During this procedure, a needle is inserted into the lower back. A small amount of the fluid that surrounds the brain and spinal cord, known as cerebrospinal fluid, is removed. The fluid is then studied to look for blood, which may mean that you have a subarachnoid haemorrhage^[8].

Treatment Options

A subarachnoid haemorrhage is a medical emergency that needs treatment right away^[1]. If it is not treated, it can lead to permanent brain damage or death^[1]. You will likely be in the hospital’s intensive care unit, where your medical team can keep a close watch on you^[11].

The main treatment for a subarachnoid haemorrhage is surgery to stop the bleeding^[6]. This may be done by^[6]:

Neurosurgical clipping: The doctor makes cuts in your scalp and through the bone of your skull. Then the doctor places a tiny metal clip over the weak part of the blood vessel. This stops the flow of blood^[6].

Endovascular coiling: The doctor makes a cut in your groin or wrist. Then the doctor moves a small plastic tube called a catheter through the cut and into a blood vessel. Using X-rays, the doctor gently guides the catheter through the blood vessel up to the brain aneurysm. Then the doctor uses a tool to fill up the aneurysm with tiny wire coils or block the opening. This keeps blood from getting back into the aneurysm^[6].

You may also have treatment before and after surgery to help the symptoms of a subarachnoid haemorrhage and lower the risk of the bleeding happening again. This might include medicine to^[6][11]:

• Help with pain
• Lower your blood pressure
• Prevent seizures (fits) or coughing
• Stop you feeling sick
• Soften your poo to make it easier to go to the toilet
• Make sure your blood flows properly

The medical team will work to control your blood pressure, manage pain, and watch for symptoms of brain damage^[19]. In the hours and days that immediately follow the bleeding, clotted blood around the brain can cause brain arteries to go into spasm, which can cause additional brain damage^[5].

You will need treatment even if your symptoms go away. This is because there is a good chance that the area will bleed again^[19].

Outlook and Recovery

About 10 to 15 percent of patients die before reaching the hospital, and 40 percent die within one month of onset^[4]. However, mortality rates have declined over the past three decades with advances in neurosurgery and neurocritical care^[4].

How a subarachnoid haemorrhage affects your life varies from person to person and depends on where in the brain the bleeding happened and the amount of damage it has caused^[6]. Although it can take months or years to get better, most people improve with treatment and some recover fully^[6].

A subarachnoid haemorrhage is a very serious condition that can lead to mental and physical disability, and significantly affect your quality of life^[6]. The problems caused by a subarachnoid haemorrhage depend on what part of the brain was affected and how much damage it caused. For example, there may be problems with movement, senses, speech, memory, thinking, or emotions^[19].

You may experience^[6]:

• Seizures (fits)
• Heart, lung or liver problems
• Cognitive difficulties, such as problems with memory, concentration and communication
• Depression and mood changes
• Feeling restless and extremely tired (fatigue)
• Headaches and unusual feelings, like water is trickling in your head or your brain is itchy

A small number of people develop epilepsy after having a subarachnoid haemorrhage^[6].

You will have regular follow-ups with your doctor and recovery team. They will talk with you about any possible complications of a subarachnoid haemorrhage and whether you need any further tests or treatment^[6]. They may want to check for any problems in your blood vessels, manage other brain aneurysms or treat a build-up of fluid around your brain (hydrocephalus)^[6].

Stroke rehabilitation, which includes training and therapy, can help with recovery^[19].

Living With the Condition

Recovery from subarachnoid haemorrhage is an individual process and there is no set pattern, so it can be difficult to predict how long recovery will take. Each person is different and you can expect to have good days and bad days during your recovery^[18].

Tiredness and fatigue: It is common to experience severe tiredness, especially in the first few months after the haemorrhage. Activities like going to the shops, watching TV, reading or talking with your friends you may find exhausting. This is because your brain has to concentrate hard to process everything going on around you and becomes tired very quickly. It is telling you to slow down^[18].

Headaches: Headaches following your discharge from hospital are common, but usually ease with time. They tend not to be as severe as when you had the haemorrhage, and can often be controlled with painkillers. Fatigue is closely associated with headaches and might become worse when you are tired^[18].

Memory and concentration: Memory and concentration problems are common following a subarachnoid haemorrhage. It can be difficult to concentrate for long periods of time and can make simple tasks difficult and frustrating. Try to break tasks down into small steps so you only have to concentrate for short periods of time before taking a rest^[18]. Many people find that their memory improves with time, although it might never be quite as good as it was before the haemorrhage^[18].

Emotions: Many people find it difficult coming to terms with having had a subarachnoid haemorrhage. You might feel depressed, tearful, angry or anxious for no apparent reason. These feelings can be physical (related to what has happened to your brain), emotional (a reaction to the traumatic experience), or both. Many of these changes are temporary and will improve over time^[18].

Unusual sensations: People often say that they experience odd or unusual sensations in their brain which are different from headaches. They are very difficult to explain but people sometimes describe them as ‘tickly’, like water running across the surface of the brain. No one knows why these sensations occur but they are common and are nothing to be concerned about. They will usually ease in time^[18].

It can help to have a daily routine. Try to get up and go to bed at the same time each day^[18]. Your recovery team can give you advice about issues like driving, work, exercise, travel and sex^[6].

Important precautions include^[18]:

• If you smoke, stop smoking
• Ensure your blood pressure is well controlled
• Keep hydrated