Subarachnoid Haemorrhage or also known as SAH is a very dangerous condition which in more serious cases can be life threatening. A Subarachnoid haemorrhage occurs when blood vessels collapse and a bleed occurs, leaking blood out over the brains surface. The main causes are said to be that of either a severe injury causing head trauma, aneurysms, arteriovenous malformations, which are defects in the blood circulation system or that of a stroke. When a subarachnoid haemorrhage occurs the blood that leaks out damages vital tissues in the brain and the loss of blood from the arteries causes brain damage which can result in temporary damage to the function of the brain and in more sever cases cause permanent damage or even death.
Although the brain is normally well protected by arteries, veins, capillaries and membranes beneath the surface of the skull, a bleed, leading to a full blown subarachnoid haemorrhage can still occur from the membrane called the arachnoid membrane. The membranes in the brain sit in layers beneath the skull bone and underneath these membranes are the arteries that provide a constant supply of blood and oxygen to the brain. The walls of these capillaries are naturally fragile and at some points where they branch out are particularly thin and prone to collapse due to the reduction in pressure of the blood passing through them as they become smaller. These points in the capillary arteries are known as branch points where the blood vessels branch out.
More than 8000 people in the United Kingdom are affected by a subarachnoid haemorrhage and for reasons unknown at the moment, the average middle-aged woman is more at risk of having a subarachnoid haemorrhage. It is said that fifty percent of people affected by a subarachnoid haemorrhage are left either severely disabled or die. For the second half of people affected by a subarachnoid haemorrhage the recovery process can have positive outcomes providing that the bleed has passed without severity. These people are normally transferred to a neurosurgical unit where the specialism is dealing with the brain and nervous system.
Signs and Symptoms of Subarachnoid Haemorrhage
- Sudden Severe Headache, like that of being struck over the head with blinding pain.
- Loss of Consciousness (in around 40% of people affected by a subarachnoid haemorrhage)
- Vomiting and Nausea
- Slurred speech
- Stiffness in the Neck
It is common to sometimes mistake a subarachnoid haemorrhage for meningitis as some of the symptoms are similar, especially with the stiffness in the neck and headaches, but in both cases urgent medical treatment is essential and an ambulance should be called immediately.
Aneurysms causing Subarachnoid Haemorrhages
Aneurysms can be the cause of a subarachnoid haemorrhage although a rare 1% of people in the UK are born with this defect. Aneurysms can also be referred to as berry aneurysms because of the way in which they are formed.
The blood vessels in the brain have extremely fragile and weak walls, which in some parts swell out like balloons as the blood passes through them. It is through the popping or bursting of these berry aneurysms that a subarachnoid haemorrhage occurs, but you would be surprised that only 7% of people in the UK are affected by a berry aneurysm cause of a subarachnoid haemorrhage.
Aneurysms causing Subarachnoid Haemorrhages happen in around 70% of people and awareness of the main contributing factors to an aneurysm bursting in the brain should be noted. The main factors are smoking, consuming excessive amounts of alcohol and lastly high blood pressure, often referred to as hypertension. Following the bursting of a berry aneurysm the blood tends to seal itself temporarily, but the weakness in the vessels is permanent and if ignored can be prone to bursting again in the future causing further leakage of blood.
Arteriovenous malformations caused Subarachnoid Haemorrhages
Arteriovenous malformations are an abnormal development of the of the blood vessels again affecting only a small minority of 1% of people in the UK. Little is known about the reasons why arteriovenous malformations occur, but it is thought that the condition is developed in the womb with the growing and development of the foetus.
Unlike the aneurysms that occur only in the brain, the arteriovenous malformations can happen anywhere in the body as the blood is being pumped, but only 1 in 10 000 people in the UK have this condition in the brain. With this condition the blood is unable to reduce in pressure as the capillaries cannot control the speed of the surging blood. During arteriovenous malformations that cause Subarachnoid Haemorrhages the veins and arteries themselves bulge and expand to the point of bursting and when they finally do burst a subarachnoid haemorrhage occurs in around 10% of people in the UK with this condition.
Diagnosis of a Subarachnoid Haemorrhage
Diagnosis of a Subarachnoid Haemorrhage takes place as soon as medical experts assess your situation. The signs and symptoms of a subarachnoid haemorrhage are checked and then diagnosis is confirmed only when a referral to the neurosurgical unit and testing is carried out in three forms. These tests are a Computerised Tomography Scan, more commonly known as CT scans, Lumbar Puncture and magnetic resonance imaging, more commonly known as MRI Scans.
Computerised Tomography (CT) Scan
A Computerised tomography (CT) scan is similar to an X-ray in the way the scan takes place, but the Computerised tomography (CT) scan differs slightly when it uses a series of scans and images to compile a three dimensional image of the brain. The main purpose of the Computerised tomography (CT) scan is to scan the brain looking for the exact location of the blood that is causing damage to the brain. Occasionally, when the blood is difficult to locate an injection of a dye can also be used to help locate the bleed. The CT scan can be quite a scary experience as the space is pretty confined, but it is very important that you have this test performed.
Lumbar Puncture Test
The lumbar puncture test is to remove a sample of the cerebral spinal fluid. The cerebral spinal fluid should be clear liquid and after a subarachnoid haemorrhage has occurred there can be traces of blood found in the sample. The lumbar puncture test includes a local anaesthetic to make the test more comfortable to endure as a needle needs to be placed into the lower spine in order to draw out a sample of cerebral spinal fluid. the lumbar puncture test does come with consent because of the nature of where you will be testing. This test is extremely reliable for detecting blood in the spinal fluid.
Magnetic Resonance Imaging (MRI) Scan
Magnetic resonance imaging (MRI) scans are used to look inside the head by using radio waves and strong magnetic fields for a more definative image of the inside of the brain. The subarachnoid haemorrhage is visible on some occasions, but predominately the blood vessels themselves are observed. The MRI scan can be a daunting experience due to the small confined space that the test is carried out in. However, the MRI scan is vital for taking segmented images of the brain and must be performed.
Treatment of a Subarachnoid Haemorrhage
After a subarachnoid haemorrhage there is always a risk that the blood vessels can spasm and bleed again so medication is usually recommended.
Nimodipine is usually given to prevent spasms of the blood vessels, but is only taken for a short duration (three weeks) due to the side effects of the drug, which are nausea, sweating, flushing of the skin, swelling to ankles, feet and or legs and stomach pains.
Surgery following a subarachnoid haemorrhage is in two forms, endovascular coiling and neurosurgical clipping. Both need to be carried out once the haemorrhage has stopped and your health is good.
Endovascular coiling is a complex art and is where small plastic tubes are entered into the leg or groin of the body and carefully threaded up to the brain where the aneurysm occurred. Smaller coils of platinum are then inserted into the tubing and placed where the aneurysm occurred therefore blocking the flow of blood from a further haemorrhage. Endovascular coiling has the greater rate of success as almost 80% of people in the UK make full recoveries with improved recovery times. Endovascular coiling surgery does not come without it’s risks and you must weigh up what other options you have as some people die from subarachnoid haemorrhages that are left in an untreated condition.
Neurosurgical clipping is the second surgical option and is carried out under a general anaesthetic. It is a delicate procedure where the scalp is cut and a small fragment of bone is removed to reveal the actual brain below. The surgeon will trace the aneurysm and when discovered will seal the vessel with a small metal clip. The bone is then replaced and fused back together, finally the skin is re stitched in place. However the success rate of this procedure holds no guarantees and therefore is always the second option.