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What is a cerebral aneurysm?


Aneurysms are weaknesses in the wall of the cerebral blood vessels that develop over time. We do not know what causes a cerebral aneurysm formation, but most studies suggest that they occur in between 2% and 5% of the whole population. Because these areas are abnormal, they have a risk of rupture (“bursting”) that can cause significant, even life threatening, problems.

Inherited risk factors associated with aneurysm formation are rare:

  • Polycystic kidney disease (PCKD) – a genetic disorder characterized by the growth of numerous cysts filled with fluid in the kidneys. PCKD is the most common medical disease associated with cerebral aneurysm formation

  • family history of aneurysms

  • connective tissue disorders (Ehlers-Danlos syndrome), fibromuscular dysplasia, hereditary haemorrhagic telangiectasia, tuberous sclerosis)

The commonest risk factors, however, are acquired:

  • cigarette smoking
  • age (> 40 years of age)
  • hypertension (high blood pressure)
  • recreational drug abuse (cocaine or amphetamine)


Although these risk factors increase a person’s risk, they do not necessarily cause aneurysm formation or rupture. Some people with one or more risk factors never develop the disease, while others develop aneurysms and have no known risk factors. Knowing your risk factors to any disease can help guide you into the appropriate actions, including changing behaviors or seeking medical advice.