Brain Aneurysm - Symptoms & Causes

What is a brain aneurysm?

A brain aneurysm, or cerebral aneurysm, is a bulge that develops in the weakened wall of an artery within the brain. This bulge or 'bubble' can fill up with blood and rupture, leading to life-threatening conditions such as a haemorrhagic stroke (bleeding into the brain).

While it is possible for anyone to have a brain aneurysm, the risk of the aneurysm bursting is higher in women and those above the age of 40.

What are the symptoms of a brain aneurysm?

Symptoms of a brain aneurysm may not be detected until it ruptures. However, if the unruptured aneurysm is large in size or presses against your brain tissues and nerves, it can cause:

  • Sudden vision changes (such as loss of vision, blurred or double vision)
  • Pain above and behind one eye
  • Dilated pupil(s)
  • Drooping eyelid
  • Paralysis or weakness in one side of the face
  • Impaired speech

The first sign of a ruptured aneurysm is a sudden, intense headache, often described as "the worst headache of my life". Other warning symptoms include:

  • Nausea and vomiting
  • Sensitivity to light
  • Neck pain
  • Seizures
  • Loss of consciousness or short blackouts
  • Confusion

Seek medical attention immediately if you notice any of these symptoms, or if you have a lingering headache that lasts for days or weeks. It could be the sign of a brain aneurysm that's leaking blood and about to burst.

What causes a brain aneurysm?

Brain aneurysms develop in a weak or defective artery wall, though the exact cause of this is not yet fully understood.

It could be a degenerative process, where factors such as increasing age and high blood pressure play a crucial role. It is also often linked to atherosclerosis, where arteries become hardened due to a gradual accumulation of fatty deposits on the artery walls.

Brain aneurysms typically form in the main arteries that run under the brain and the base of the skull, or at 'forks' in the arteries where the walls are weaker.

What are the risk factors for a brain aneurysm?

Certain genetic disorders and circulation diseases greatly increase the likelihood of developing a brain aneurysm.

Known risk factors for brain aneurysms include:

  • Family history. If you have a close relative who developed a brain aneurysm, such as your parent or sibling, you are at higher risk of developing it too.
  • Genetic disorders. Connective tissue disorders such as Ehlers-Danlos syndrome and Marfan syndrome cause weakened blood vessel walls, thus increasing the risk of an aneurysm.
  • Congenital conditions. Inherited conditions present since birth, such as polycystic kidney disease, arteriovenous malformations and coarctation (narrowing) of the aorta, can also weaken blood vessels and raise the risk of brain aneurysms.
  • Hypertension. Uncontrolled high blood pressure exerts additional pressure on the artery walls and can lead to weakened areas.
  • Alcohol and drug abuse. Excessive consumption of alcohol and drugs, especially cocaine, raises blood pressure and induces inflammation of the arteries.
  • Smoking. This is a significant risk factor for brain aneurysms that can be modified through lifestyle changes.
  • Head injuries. In some cases, a severe head injury can damage blood vessels in the brain and lead to an aneurysm.
  • Infections. Though rare, some infections can cause arterial wall damage and increase the risk of mycotic aneurysms.
  • Increasing age. Brain aneurysms are more commonly found in people over the age of 40.
  • Gender. Women are more likely than men to develop brain aneurysms.

An unruptured brain aneurysm increases pressure within the skull. When the aneurysm ruptures, regular blood flow is disrupted and blood leaks out into the surrounding brain tissue, affecting your brain's oxygen and blood supply. This can result in serious complications such as a haemorrhagic stroke, permanent brain damage, coma or even death.

Brain aneurysms can also cause other complications such as:

  • Re-bleeding. A burst aneurysm may bleed again and cause further damage to brain cells.
  • Vasoplasm. Narrowing of the blood vessels reduces oxygen supply to the brain and may lead to a stroke.
  • Hydrocephalus. Ruptured aneurysms can cause an abnormal build-up of cerebrospinal fluid that surrounds your brain and spinal cord, leading to possible brain damage.
  • Hyponatremia. Bleeding in the brain disrupts sodium levels in the blood, causing swelling of brain cells and irreversible damage.
  • Fits (seizures). Aneurysm bleeding can also cause electrical disturbances in the brain and uncontrolled muscle convulsions.

How do you prevent a brain aneurysm?

There is no proven way to prevent brain aneurysms. However, you can reduce your risk by making some lifestyle and dietary changes:

  • Stop smoking
  • Avoid drugs
  • Get timely treatment for high blood pressure
  • Limit alcohol and caffeine intake
  • Eat a healthy diet with less salt
  • Exercise regularly
  • Maintain a healthy weight
This page has been reviewed by our medical content reviewers.

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