Q1. What is a brain aneurysm?
An aneurysm is not a tumour, nor a type of cancer. It is a ‘bulge’ in the blood vessel wall. When part of the vessel wall becomes weakened, it bulges out under effect of blood pressure. It usually occurs at the bifurcation of blood vessel. A brain aneurysm occurs when the bulge grows in size and the weakest spot bursts, causing cerebral haemorrhage.
Q2. What are the symptoms and risks of brain aneurysms?
Most brain aneurysms are asymptomatic until they rupture. When it happens, it results in a situation known as subarachnoid haemorrhage – a very serious and potentially life-threatening haemorrhagic stroke. The patient will experience a very agonizing pain in the head, and even the neck. It is often described as a ‘thunderclap headache’ or ‘worst ever headache’. Some patients will lose their consciousness immediately. A small portion of unruptured aneurysm may cause symptom if it exerts pressure in a nearby nerve in the brain. For example, if the third cranial nerve (oculomotor nerve) is compressed, the patient will have dropped eye lid and dilated pupil on that side.
Q3. How does a brain aneurysm develop? Who are prone to having brain aneurysm?
It is believed in the medical profession that brain aneurysms are either congenital or acquired, the two factors continue to interact. Some people are born with weaker blood vessel wall. With aging of blood vessel wall and rise in blood pressure, and when certain part of the blood vessel wall becomes weakened, it bulges out under influence of blood pressure. This usually occurs where the artery branches. Known risk factors are smoking and poorly controlled hypertension. Typical age of presentation is between 40 to 50s. Female gender has a slight predominance. People with genetic factor that weakened their connective tissue, such as polycystic kidney disease, Marfan’s syndrome, Ehlers-Danlos syndrome, are more prone to suffer from this situation.
Q4. What are the treatment options for brain aneurysm?
The aim of treating aneurysm is to prevent rupture and its devastating consequence of brain haemorrhage. If the risk of rupture is high, one should consider receiving treatment. Conventional methods involve open surgery, where doctors put clips to seal the aneurysm under operating microscope. Nowadays most cases can be treated by catheter-based minimally invasive surgery. This can be done either by filling it with coils or sealing it with stent.
The first method is coil embolization. It is a minimally invasive procedure where doctors place small catheter into the artery and deploy metal coils to fill up the aneurysmal sac for protection. However, if the entry point of the aneurysm is too wide, the coil may herniate from the aneurysmal sac and cause blockage of normal parent artery. Alternatively, one can use ‘flow-diverting’ stent to cover the opening of the aneurysm and facilitate its sealing up. This is especially useful when the aneurysm is large and its opening is wide. This approach is technically safer than coil embolization but it may not suit all cases. Patients will need to take blood thinner or antiplatelet drugs for a period of time, thus those with ruptured aneurysm may not be suitable for the procedure.
Q5. Do all brain aneurysms require treatment?
Ruptured aneurysm needs early treatment to prevent rebleeding. Even if patients survive the initial aneurysmal rupture, the risk of rebleeding is high. Its consequence is even worse. Therefore if the aneurysm has ruptured, it is important for the patient to receive treatment to prevent rebleeding. However, not all unrupturued aneurysms need treatment.
Patients may then ask what conditions require treatment? Their risk of rupture depends on several factors: its size, shape and location. Generally speaking, the larger the aneurysm, the larger will be the rupture risk. Doctors usually recommend treatment for aneurysms that are larger than 4mm in diameter. As research has shown that aneurysms larger than 5mm in diameter are at higher risk of rupture.
Another factor to consider is the shape of the aneurysm. If the configuration of aneurysm is smooth and like a perfect sphere, the thickness of the blood vessel wall is likely to be more uniform. However if there is an additional small bulge arising from the main sac, the area would be further weakened and bear even more pressure. In other words, it is at higher risk to rupture. If such condition is found, treatment should be considered.
Other factors include patient’s age, general health status and associating medical condition, whether he or she needs to take blood thinner, and whether there were previous history of brain haemorrhage. Patients with more than one brain aneurysms or if the aneurysm has ruptured before, the remaining aneurysms are at higher risk to rupture. One should actively consider receiving treatment.
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