Aneurysm

What is an Aneurysm?

An aneurysm is a bulge or dilation along a blood vessel in the brain. Most aneurysms are identified either incidentally during an imaging procedure for something unrelated or because the person is suspected of having bleeding in their brain.

Many aneurysms do not cause any symptoms and go undetected for life. Still, others are at risk of bursting or rupturing, which can cause significant complications and high rates of disability or death. Addressing aneurysms early when they are unruptured can help prevent these complications.

What Are the Different Types of Aneurysms?

About 85% of aneurysms are located near the front of the head near an area of the brain called the circle of Willis, a ring of blood vessels at the base of the brain that connects the four major blood vessels.

Once an aneurysm is identified, it is classified based on its appearance (shape, size, and location). The three main types of brain aneurysm are:

• Fusiform, which looks like a balloon within the blood vessel.
• Saccular, which is round with a sac around it and looks like a berry attached to a branch. This is the most common form of aneurysm. The rupture rate of saccular aneurysms is higher fusiform aneurysms, so they are considered more severe.
• Mycotic, which is associated with an infection and looks like a bulge on one side of the blood vessel.

An aneurysm might also be classified based on its size as small, large, or giant. Size is an important determinant of the risk of rupture, with larger aneurysms being more likely to burst. A small aneurysm is only the size of a pencil eraser, whereas a large aneurysm is about as big as a dime. Giant aneurysms can be as big as a quarter or larger.

How Common Are Aneurysms?

It is difficult to determine the number of people who are affected by aneurysms each year because most are undetected until death, when there may be an autopsy. Despite this, it is estimated that between 0.2% and 10% of people in the United States have an unruptured aneurysm.

The number of people diagnosed with aneurysms has increased over the past few decades. This could be due to increased testing or the fact that there are more people living over 75 who are at higher risk of having an aneurysm.

Who is at Risk for an Aneurysm?

Brain aneurysms can occur at any age. However, they are most commonly diagnosed in people 30-60 years old.

The risk of having an aneurysm is higher in people with certain medical conditions like connective tissue disorders, blood vessel malformations, and polycystic kidney disease and in people with a close relative who had an aneurysm.

Some risk factors include:

• Cigarette smoking
• Untreated high blood pressure
• Drug & alcohol abuse
• High cholesterol
• Diabetes
• Advanced age
• Physical inactivity
• Tumors
• Trauma
• Infections
• Family history of aneurysms or strokes
• Estrogen deficiency
• Certain genetic conditions

The risk of a rupture is increased in people with large aneurysms, aneurysms in the blood vessels located near the back of the head, and aneurysms that are growing in size. Rupture is also more likely in people with relatives with a history of ruptured aneurysms. Women are also more likely to have a ruptured aneurysm compared to men.

What Are the Symptoms of an Aneurysm?

Unruptured aneurysms do not usually have symptoms, which is why they are difficult to detect. However, there are some signs that could indicate an unruptured aneurysm, including :

• Problems with vision
• Numbness or a lack of movement on one side of the face
• Trouble speaking
• Balance issues
• Memory or concentration problems

People who have a ruptured aneurysm typically experience a severe headache that comes on suddenly. This is often described as a thunderclap headache or the worst headache the person has ever experienced. Symptoms may also include:

• Seizures
• Loss of consciousness
• Neck stiffness
• Lower back pain
• Fever
• Nausea and vomiting
• Drowsiness
• Increased sensitivity to light (photophobia)
• Problems moving one side of the body
• Sudden confusion

Aneurysms are very serious medical concerns. If you suspect you or a loved one has an aneurysm, seek medical attention immediately.

What Are the Complications of an Aneurysm?

Aneurysms, especially those that rupture, are associated with many possible complications. An aneurysm can lead to increased fluid in the skull that puts pressure on the brain, causing various symptoms related to the part of the brain that is being compressed.

The bleeding resulting from a rupture can cause the blood vessels to contract abnormally and limit blood flow to different brain areas. The lack of circulation can cause the cells in the brain to become damaged or die. Other common complications of aneurysms are blood clots, stroke, arrhythmias, congestive cardiac failure, pulmonary edema, epilepsy, and paralysis.

How Is an Aneurysm Diagnosed?

An aneurysm is diagnosed through imaging techniques like a computer tomography (CT) scan or magnetic resonance imaging (MRI).

A CT scan is usually performed first because it can be done quickly. It produces a two-dimensional image of the brain and can show bleeding. A more precise view can be obtained by injecting a dye into the bloodstream; this technique is called a CT angiogram.

An MRI can produce either two- or three-dimensional images and can show the shape and size of the aneurysm without the need for dye. This method is more expensive and takes more time, so it is not typically the first imaging strategy used for diagnosis.

A healthcare provider may also perform a spinal tap, a sampling of the fluid around the spine, to determine whether there is blood that would indicate bleeding in the brain. A cerebral angiogram may be used if a spinal tap or imaging methods don’t produce a definitive answer. In this procedure, a tiny tube is inserted into a blood vessel in the arm or leg and gently pushed to the head, where dye is injected, and X-rays are used to visualize the blood vessels in the brain.

How Is an Aneurysm Treated?

Treatment typically involves one of two strategies, depending on the risk of rupture: surgery or endovascular coiling.

Surgical Intervention

During surgery, after removing a small portion of the skull, a tiny metal clip is placed on the blood vessel to isolate the aneurysm. After the clip is placed, the bone is typically put back, and the scalp is stitched. Over time, the aneurysm becomes small and produces a scar. The clip remains in the brain because it doesn’t generally cause any long-term issues, and removal would have more risk than leaving it in place.

Endovascular Coiling

During an endovascular coiling procedure, a trained healthcare provider inserts a tiny tube through a blood vessel in the leg and feeds it toward the head. Once the tube reaches the aneurysm, a second tube containing a tiny platinum coil is inserted into the first tube. The platinum coil fills the aneurysm. An electrical current is used to free the coil from the tube so it stays inside the aneurysm. It’s thought that the current that detaches the coil attracts components of the blood to promote clotting that destroys the aneurysm. This is a less invasive treatment because only a small incision is required in the leg rather than a surgery that requires bone removal.

How To Prevent Brain Aneurysms

Aneurysms can be difficult to prevent, but you can decrease your risk by maintaining a healthy lifestyle that includes:

• Limiting alcohol and caffeine intake
• Exercising regularly
• Eating a healthy diet
• Stopping smoking
• Seeking treatment for high blood pressure
• Maintaining a healthy weight

What Is the Prognosis for People With an Aneurysm?

The prognosis for people with unruptured aneurysms is excellent, especially with treatment, with fewer than 10% of cases being fatal.

People with ruptured aneurysms experience higher mortality rates, with about 25% dying within the first 24 hours and 50% dying within three months. The prognosis for those with an aneurysm is better in younger people, with 80%-90% of children with ruptured aneurysms surviving.

Outlook

Unruptured aneurysms have a favorable prognosis when addressed early. Surgical interventions are largely successful in removing the aneurysm, and full recovery is possible.

If you or a close family member has a history of aneurysms, regular visits with your healthcare provider, who can perform screening tests and monitor your health, will greatly reduce your risk of complications.