September is Brain Aneurysm Awareness Month

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What is a brain aneurysm? 

A brain aneurysm is a potentially life-threatening condition. It occurs when a bulge forms at a weak or thin area of a blood vessel in the brain. This area balloons out as it fills with blood, and the weakened vessel wall is at risk of a leak or rupture. Aneurysms can occur in any artery in the brain, but are commonly seen near the bottom of the skull or near the point where an artery branches.

There are three main types of brain aneurysms: 

  • Saccular aneurysms are the most common. These occur when a bulge forms on one side of an artery wall, creating a rounded dome that fills with blood. Saccular aneurysms are often referred to as “berry” aneurysms, as they resemble a berry hanging off of a branch.
  • Fusiform aneurysms occurs when a bulge forms on both sides of the artery. There is no defined dome, but rather a complete widening of the vessel.
  • Mycotic aneurysms are the least common. These may form following an infection that impacts and weakens the blood vessels in the brain.

Brain aneurysms are also described based on size:

  • Small: < 11 millimeter diameter
  • Large: 11-25 millimeter diameter
  • Giant: > 25 millimeter diameter

Approximately 6.5 million people in the United States have an unruptured brain aneurysm, with 20% ultimately diagnosed with more than one. Many small aneurysms will remain stable when monitored over time. However, it is estimated that every year nearly 30,000 of these individuals will experience a brain aneurysm rupture. This is equivalent to one rupture every 18 minutes

What are the symptoms?

A small, unruptured brain aneurysm may not cause any symptoms. These are often found incidentally while testing or performing imaging for other medical conditions.
A large, unruptured aneurysm in the brain may press on nerves or surrounding tissues causing stroke-like symptoms such as:

  • Pain above or behind one eye 
  • Numbness on one side of the face
  • Vision changes (blurred vision, double vision, a dilated pupil) 

In more severe cases, a brain aneurysm may leak or rupture resulting in bleeding in the brain. If blood pools between the brain and the surrounding tissue, it can cause a stroke known as a subarachnoid hemorrhage.
The most common symptom of a brain aneurysm rupture is a sudden, intense headache. A person may describe this sudden headache as the worst head pain of their life. Other symptoms may include:

  • Nausea and vomiting
  • Neck pain or stiffness
  • Vision changes
  • Seizure
  • Light sensitivity 
  • Drooping eyelid
  • Loss of consciousness
  • Confusion

Bleeding in the brain can cause cell and tissue death. It can also result in an increase in pressure ultimately impacting the supply of blood and oxygen to critical structures. This has the potential to cause serious injury and complications in a short amount of time.

It is important to call 911 or seek emergency medical care immediately if an individual experiences symptoms of a ruptured aneurysm.
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Who is at risk?

Brain aneurysms can impact anyone, but are less commonly seen in children. They are most frequently diagnosed in individuals over the age of 40, with a higher occurrence seen in women compared to men. The risk of aneurysm typically increases with age.

Some risk factors are inherited or present from birth, such as a family history (Familial aneurysms) or an underlying connective tissue disorder (i.e. Ehlers-Danlos, Fibromuscular Dysplasia). There is also a risk of developing a brain aneurysm after a severe head injury or infection.

Other risk factors that are more controllable and related to lifestyle choices include alcohol use, smoking, and high blood pressure. These can lead to damage and weakening of blood vessels over time. 

What’s the prognosis?

Unruptured brain aneurysms are often monitored over time to look for any change or growth. Some may never cause symptoms or require intervention. Others may be deemed less stable. In that case, therapeutic or surgical treatment options may be considered. This varies on a case-by-case basis. An individual’s age, health status, personal risk factors, and family medical history will all impact treatment options. 

Treatment may also vary depending on the size of the aneurysm and where it is located in the brain. Patients are often encouraged to make lifestyle modifications, such as quitting smoking or managing blood pressure with diet and exercise.

A ruptured brain aneurysm is a medical emergency, with nearly half of all incidents resulting in death. Statistics show that 15% of deaths occur prior to an individual reaching the hospital or receiving medical care. The majority of those who survive the initial event will experience some sort of long term damage or neurologic impairment. Recovery from a brain aneurysm rupture can take months or longer.

Prognosis and expected outcomes improve with early recognition and diagnosis of a brain aneurysm or rupture. It allows for appropriate monitoring or initiation of any critical medical treatment if needed. The end goal is to minimize the risk of a potentially devastating injury or fatality.