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Brain Aneurysm

A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. In most cases, a brain aneurysm causes no symptoms and goes unnoticed. In rare cases, the brain aneurysm ruptures, releasing blood around the base of the brain and causing a type of stroke called a subarachnoid hemorrhage. Patients experience a severe headache known as a “thunderclap headache.” Urgent medical evaluation is necessary after aneurysms become symptomatic.

What are the risk factors for a brain aneurysm?

A person may inherit the tendency to form aneurysms, or aneurysms may develop because of hardening of the arteries (atherosclerosis) and aging. Some risk factors that can lead to brain aneurysms can be controlled, others cannot. The following risk factors may increase your risk for an aneurysm or, if you already have an aneurysm, may increase your risk of it rupturing:

  • Family history — People with a family history of brain aneurysms are more likely to have an aneurysm than those who don't.
  • Previous aneurysm — People who have had a brain aneurysm are more likely to have another.
  • Gender — Women are more likely to develop a brain aneurysm and subarachnoid hemorrhage.
  • High blood pressure — The risk of subarachnoid hemorrhage is greater in people with a history of high blood pressure.
  • Smoking — In addition to being a cause of high blood pressure, smoking greatly increases the chances of a brain aneurysm occurring or rupturing. Although only 10 percent to 20 percent of the population smokes, 75 percent of patients admitted to a hospital with a ruptured aneurysm are smokers.

Symptoms of a ruptured brain aneurysm often come on suddenly. If you have any of the following symptoms or notice them in someone you know, call 911 or other emergency services right away:

  • A sudden, severe headache that is the worst headache you’ve ever had
  • Neck pain
  • Nausea and vomiting
  • Sensitivity to light
  • Fainting or loss of consciousness
  • Seizures

If you have non-emergency questions about brain aneurysms, call the Virginia Mason Neuroscience Institute at (206) 341-0420.