A cerebral aneurysm is a bulge that occurs in the wall of a blood vessel, usually at the point where it branches and the walls are weaker. As blood flows through the vessel, the wall bulges under pressure and is at risk of rupturing.
A ruptured or burst aneurysm is termed subarachnoid hemorrhage, a dangerous event that can lead to paralysis, long-term disability and even death.
Although the exact cause of cerebral aneurysm is not always clear, several risk factors have been identified. Some examples of these risk factors include:
Smoking is one of the major risk factors for cerebral aneurysm. People diagnosed with cerebral aneurysm are usually current or past smokers. Although the exact mechanism for this association is not clear, it is thought that the toxic substances in tobacco smoke may damage and weaken the vessel walls.
Individuals who have a first-degree relative with a history of cerebral aneurysm are twice as likely to develop the condition compared with people who do not have such a family history, although this risk is still very small at around 2%.
High blood pressure
High blood pressure or hypertension is another major risk factor for cerebral aneurysm, due to the increased pressure placed on vessel walls as the blood flows through them. Some of the factors that increase the risk for hypertension include being overweight, being inactive, having a family history of hypertension, consuming a lot of salt, drinking a lot of alcohol or coffee and being over 65 years of age.
The risk of cerebral aneurysm increases with age, with cases usually occurring after the age of 40 years. The blood vessel walls are thought to weaken over time, as blood continually flows through them.
Some birth defects
Certain birth defects that give rise to weak blood vessels also increase the risk of cerebral aneurysm. Examples include autosomal dominant polycystic kidney disease (ADPKD), Type IV Ehlers-Danlos syndrome, Marfan syndrome and coarctation of the aorta.
In rare cases, severe head injury can also cause cerebral aneurysm if the brain’s blood vessels are damaged.
Cocaine abuse raises the risk for cerebral aneurysm because it inflames blood vessel walls and also increases blood pressure.
Reviewed by Sally Robertson, BSc