Brain Aneurysm

What is a Brain Aneurysm?

A brain aneurysm (also called a cerebral or intracranial aneurysm) is a weak, bulging area in the wall of a blood vessel in the brain. Over time, the pressure of blood flowing through the artery can cause this weak spot to balloon outward. Many brain aneurysms are small, cause no symptoms and never rupture. However, if an aneurysm leaks or bursts, it causes bleeding in or around the brain, called a subarachnoid hemorrhage. A ruptured brain aneurysm is a type of hemorrhagic stroke and a life-threatening medical emergency that requires immediate care.

What Are the Types of Brain Aneurysms?

• Saccular (berry) aneurysm: The most common type. It looks like a small, round sac or berry attached to an artery, often where blood vessels branch.
• Fusiform aneurysm: A less common type in which the artery bulges outward on all sides.
• Mycotic aneurysm: A rare type caused by an infection that weakens the artery wall.

Aneurysms are also described by size. Most are small, but aneurysms larger than about one inch are called giant aneurysms and can be more difficult to treat.

How common Are Brain Aneurysms?

Brain aneurysms are more common than many people realize. According to the Brain Aneurysm Foundation, an estimated 6.8 million people in the United States, or about 1 in 50, have an unruptured brain aneurysm. About 30,000 people in the U.S. experience a ruptured brain aneurysm each year. Brain aneurysms are most common in adults ages 35 to 60, and women are more likely than men to have one. The good news is that an estimated 50% to 80% of brain aneurysms never rupture, which is why accurate detection and monitoring are so important.

Symptoms & Causes

Most unruptured brain aneurysms do not cause symptoms and are often found by chance during imaging for another reason, such as a head injury or headaches. Symptoms depend on whether the aneurysm is unruptured, leaking or ruptured.

Symptoms of an Unruptured Brain Aneurysm

A larger unruptured aneurysm may press on nearby nerves or brain tissue and cause:

• Pain above or behind one eye
• A dilated pupil
• Blurred or double vision
• Numbness or weakness on one side of the face

Symptoms of a Leaking or Ruptured Brain Aneurysm

Symptoms of a leaking or ruptured brain aneurysm may include:

• Sudden, severe headache, often described as the worst headache of your life
• Nausea and vomiting
• Stiff neck
• Blurred or double vision
• Sensitivity to light
• Seizure
• Drooping eyelid
• Confusion
• Loss of consciousness

A ruptured brain aneurysm can also cause stroke symptoms. 

Remember BEFAST

• B – Balance: Sudden loss of balance or coordination
• E – Eyes: Sudden vision changes
• F – Face: Facial drooping or numbness
• A – Arms: Arm weakness or numbness
• S – Speech: Slurred speech or difficulty speaking
• T – Time: Call 911 immediately if these symptoms occur.

Some people have a sudden, severe headache days or weeks before a rupture, which may be caused by a small leak. If you or someone near you has a sudden, severe headache or any of these symptoms, call 911 right away.

What Causes a Brain Aneurysm?

Brain aneurysms develop when the wall of an artery in the brain becomes thin or weak. Most form gradually over time, often after age 40, as a result of wear and tear on blood vessels combined with ongoing pressure from blood flow. Some people are born with a weakness in an artery wall or inherit a tendency toward weaker blood vessels. In rare cases, an aneurysm can form after a severe head injury or an infection.

What are the Risk Factors for a Brain Aneurysm?

• Smoking
• High blood pressure (hypertension)
• Age over 40
• Being female
• Family history of brain aneurysms, especially in a parent, sibling or child
• Heavy alcohol use
• Drug use, particularly cocaine or amphetamines
• Certain inherited conditions, such as polycystic kidney disease, connective tissue disorders (like Ehlers-Danlos syndrome or Marfan syndrome) and coarctation of the aorta
• Arteriovenous malformation (AVM) in the brain

What are the Complications of a Brain Aneurysm?

A brain aneurysm can lead to serious complications, particularly if it ruptures, including:

• Rupture and subarachnoid hemorrhage: When an aneurysm ruptures, it causes bleeding in the space surrounding the brain, known as a subarachnoid hemorrhage.
• Vasospasm and delayed cerebral ischemia: Blood vessels in the brain can narrow after a rupture, reducing blood flow and potentially causing additional brain injury or stroke.
• Hydrocephalus: Blood can interfere with the normal circulation of cerebrospinal fluid, causing fluid to build up and increase pressure in the brain.
• Rebleeding: A ruptured aneurysm can bleed again, particularly before it has been treated.
• Seizures and long-term neurologic deficits: Bleeding and resulting brain injury may cause seizures or lasting neurologic problems.

Because these complications can develop quickly, fast diagnosis and treatment at a hospital with specialized neurovascular expertise is critical.

Diagnosis & Treatment

How is a brain aneurysm diagnosed?

Brain aneurysms are diagnosed with imaging tests that show the blood vessels in the brain. Some aneurysms are discovered during an emergency visit for a sudden, severe headache. Others are found incidentally on scans ordered for another reason. Your care team may use one or more of the following tests:

• CT scan: Often the first test used in the emergency department to check for bleeding in the brain.
• CT angiogram (CTA): Uses contrast dye and CT imaging to create detailed pictures of the brain’s arteries and can detect an aneurysm.
• MRI and MR angiogram (MRA): Uses magnetic fields and radio waves to show the size, shape and location of an aneurysm without radiation.
• Cerebral angiogram: A thin catheter is guided through an artery to the brain, and contrast dye is injected to provide highly detailed X-ray images of blood vessels. This test is often used when more detail is needed to plan treatment.
• Lumbar puncture (spinal tap): If a ruptured aneurysm is suspected but a CT scan does not show bleeding, a sample of spinal fluid may be tested for signs of blood.

AI-Powered Aneurysm Detection with Rapid Aneurysm

MemorialCare Neuroscience Institute uses Rapid Aneurysm, developed by RapidAI®, to help physicians identify and track brain aneurysms on medical imaging. This artificial intelligence (AI) technology automatically analyzes brain imaging studies and flags suspected aneurysms for the care team to review.

Rapid Aneurysm also creates detailed three-dimensional measurements of an aneurysm’s size, shape and volume, and tracks changes over time. This objective, consistent data helps physicians spot growth or other changes more precisely than with manual measurements alone, supporting earlier identification of aneurysms that may need treatment. Because the technology is built into MemorialCare’s imaging workflow, AI-assisted analysis is available as part of routine care without additional appointments or delays.

How is a Brain Aneurysm Treated?

Treatment depends on whether the aneurysm has ruptured, as well as its size, shape and location, your age and overall health. MemorialCare’s multidisciplinary neurovascular team, including interventional neuroradiologists, neurosurgeons and neurologists, works together to create a personalized treatment plan.

Monitoring (Active Surveillance)

Many small, unruptured aneurysms with a low risk of rupture can be safely watched over time with regular imaging. Tools like Rapid Aneurysm help physicians compare scans and detect even small changes in size or shape, so treatment can begin if an aneurysm starts to grow. During monitoring, controlling blood pressure and quitting smoking are important to lower risk.

Endovascular Treatment

Endovascular procedures treat aneurysms from inside the blood vessel using a thin catheter, usually inserted through an artery in the groin or wrist, with no open brain surgery. At MemorialCare, minimally invasive aneurysm embolization uses tiny coils, sometimes supported by stents, to fill the aneurysm and block blood from flowing into it. Other endovascular options may include flow-diverting stents, which redirect blood flow away from the aneurysm so it can gradually seal off.

Surgical Clipping

In some cases, a neurosurgeon may recommend surgical clipping. During this procedure, the surgeon makes a small opening in the skull and places a tiny metal clip across the base of the aneurysm to stop blood from flowing into it.

Emergency Care for a Ruptured Aneurysm

A suspected ruptured brain aneurysm is a medical emergency. Call 911 immediately. Emergency treatment focuses on stopping the bleeding and preventing rebleeding, usually with endovascular coiling or surgical clipping. Patients are closely monitored in an intensive care setting, where the team may give medications to help prevent vasospasm, manage blood pressure and drain excess fluid from the brain if needed.

What is the Recovery Process for Brain Aneurysm Treatment?

Recovery depends on the type of treatment and whether the aneurysm ruptured. After a minimally invasive procedure for an unruptured aneurysm, many patients stay in the hospital for a short time. Patients recovering from a rupture usually need a longer hospital stay and may benefit from physical, occupational and speech therapy through MemorialCare’s rehabilitation services.

Recovery at Home

At home, follow your care team’s instructions about activity, medications and wound care. Most patients need follow-up imaging to make sure the aneurysm remains sealed. Call your doctor if you have a sudden severe headache, new weakness, vision changes or confusion. Support groups can also help patients and families adjust after treatment.

Prevention

Not all brain aneurysms can be prevented, especially those linked to inherited conditions. However, healthy habits can lower the risk of an aneurysm forming, growing or rupturing:

• Quit smoking and avoid secondhand smoke
• Keep blood pressure under control through regular checkups, medication if prescribed, exercise and a heart-healthy diet
• Limit alcohol
• Avoid stimulant drugs such as cocaine and amphetamines
• Talk with your doctor about screening if two or more close family members have had a brain aneurysm or if you have a condition that raises your risk

If you already have an unruptured aneurysm, keeping up with follow-up imaging allows your care team to track changes and recommend treatment at the right time.

What is the Outlook for Someone With a Brain Aneurysm?

The outlook for people with an unruptured brain aneurysm is often very good, since many never rupture and those that need treatment can often be repaired before problems occur. A ruptured aneurysm is far more serious: about half of ruptures are fatal, and many survivors have lasting effects. This is why early detection, careful monitoring and fast emergency care make such a difference. With advanced imaging, AI-assisted analysis and a dedicated neurovascular team, MemorialCare helps patients get the right care at the right time.