Pathology Spotlight: Brain Aneurysm

Our Human Remains Conservator takes a look at Brain Aneurysms in our latest Pathology Spotlight blog.  

The walls of our arteries and veins are composed of three layers,  with varying amounts of elasticity to respond to the pulses of blood that come from the heart’s regular beating. Sometimes areas of the wall can become thin and weak, and the pressure of the blood pushing on the wall can cause the thinned area to bulge outwards, like a balloon filled with blood. This is called an aneurysm, and one of the most common places in the body where this happens is the brain. It can be completely asymptomatic, unless the aneurysm bursts when it leads to a serious medical emergency caused by bleeding in the the brain. The first sign can be a ‘thunderclap headache’ – an agonising pain in the head that comes  on suddenly – along with a stiff neck, nausea and vomiting, and a painful response to light. Ruptured aneurysms also occur in other sites where the blood is at high pressure, such as the abdominal aorta.

Since the disease process that causes the weakening of the vessel wall is normally atherosclerosis, the condition that leads to heart attacks and strokes, predisposition to having an aneurysm is often through the same lifestyle factors that influence coronary heart disease. These are smoking, binge drinking, fatty foods, high blood pressure, or use of stimulant drugs, although genetics clearly has a role as people are more likely to develop it if there is a familial history of brain aneurysm. They become more common as you get older, and women are more likely to suffer than men. Diagnosis of an aneurysm can be done through an MRI scan or CT scan, or by an angiogram.

If an unruptured aneurysm is discovered, the likelihood of it bursting is assessed. If likely, a surgical procedure can be carried out placing a metal clip over the opening to the aneurysm to cut off the blood supply. This is a risky procedure which involves opening the skull. A non-surgical alternative involves introducing a catheter through a vessel in the groin, which can be threaded up to where the aneurysm is located. Once there, tiny platinum coils are introduced into the aneurysm to stop the blood flow. This is called endovascular coiling, and while it is safer than clipping, there is a greater chance of further blood flow into the aneurysm. If the risk of rupture is low, lifestyle changes such as a low fat diet, reduced smoking and stimulants, and avoidance of heavy lifting, combined with medication that lowers blood pressure, can reduce the chances of the aneurysm bursting or leaking.

This specimen shows an aneurysm in the circle of Willis, a circle of arteries on the base of the brain responsible for supplying it with blood. It is the most common site of aneurysm in the brain


Aneurysm in the circle of Willis, with the arrow indicating the site of the aneurysm
Angiogram showing an aneurysm in the brain- the aneurysm is the bean-like structure in the centre. An angiogram is a diagnostic tool where a substance that can be seen under X-ray is introduced into the blood vessels so that blood flow can be visualised. Source: Wikicommons

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