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An aneurysm is a protrusion in the wall of a blood vessel. Aneurysms can form in any artery, anywhere in your body, including in your brain. However, most aneurysms occur in the aorta - the body's largest artery, which travels from your heart down the center of your chest and abdomen, eventually splitting off into two arteries, one that serves each leg.

How serious an aneurysm is depends on its size and location as well as your age and health. While small aneurysms can often be left alone, treatment should be considered for larger aneurysms. A ruptured aneurysm can quickly become life-threatening and requires prompt medical attention.

The two most serious types of aneurysms are aortic and brain aneurysms. Although less common, a brain aneurysm is a bulge in an artery in your brain that could become life-threatening should it rupture. Most brain aneurysms are discovered in people ages 35 to 60 and are slightly more common in women than men.

The decision to treat an unruptured aneurysm depends on a number of factors, including the type, location and size of the aneurysm, your age and general health and risks of treatment. Small, unruptured aneurysms that appear to pose little risk of rupture, may not need to be treated. Nebraska Medicine offers several new and cutting edge treatment options to treat aneurysms which are described below. It is important to discuss your options with your physician. A more detailed discussion on aneurysms follows.

Aneurysms are commonly classified based on shape, multiplicity, size and symptomatic factors. Below is a chart of aneurysm classifications and a clarifying description:

  • Saccular or Berry

    Most frequent aneurysm. Arise at points of congenital weakness in the arterial wall, commonly at branching points where the parent vessel is curving.

  • Dissecting

    May occur after trauma or spontaneously. Developing of a tear in the intima allows blood under arterial pressure to force apart the layers of the arterial wall, forming a false lumen. More commonly involve the posterior circulation than the anterior circulation.

  • Fusiform

    Tend to occur on vessels as a result of atherosclerotic loss of elasticity or other trauma. Most often seen in the vertebral or basilar artery.

  • Mycotic

    Usually arise at the sites of microemboli from cardiac or pulmonary sepsis. Bacteria or fungi are known to be the causative agents. Loss of elastic tissue and damage to the intima (due to inflammatory disease) are the characteristic pathologies.

  • Neoplastic

    Result from tumor emboli and subsequent growth of the neoplasm through the vessel wall. Seen with atrial myxoma and choriocarcinoma.

  • Pseudoaneurysm

    Organized hematoma from a vessel that has bled. No true vessel walls. Pathologically distinguished by concentric rings of fibrin and organized blood.

  • Traumatic

    Occur as a result of injury to the arterial wall. Fibrous organization of the hematoma leads to formation of the aneurysm. Located on the longitudinal aspect of the arterial wall as compared with berry aneurysms, which tend toward bifurcation regions. Usually located on the middle or anterior cerebral arteries.

Although most aneurysms occur sporadically, there is a familial incidence (7 to 20 percent of patients with aneurysmal subarachnoid hemorrhage have a first- or second-degree relative with a confirmed intracranial aneurysm), with siblings having the highest association. Certain conditions, particularly connective tissue disorders or abnormalities of blood flow, have an increased propensity for aneurysms.

Rupture of an aneurysm carries a significant morbidity and mortality rate. Fifty to 70 percent of subarachnoid hemorrhages are the result of the rupture of an intracranial aneurysm. Cigarette smoking is associated with three to 10 times the risk of aneurysmal subarachnoid hemorrhage. Patients with untreated ruptured aneurysms continue to have a substantial long-term risk, as an aneurysm which has ruptured once has a high risk of rupturing again.

Aneurysm Diagnosis

Unruptured aneurysms are most likely to be discovered during conventional or magnetic resonance (MR) angiography. Magnetic resonance angiography and CT angiography are being used increasingly to screen patients with suspicious headache and family history of intracranial hemorrhage.

Intraarterial contrast angiography is performed to eliminate vascular overlap and provide stereoscopic images of the aneurysm. Rotational angiography and angiography with three-dimensional reconstruction provide excellent visualization of the anatomical arrangement of the aneurysm. In this procedure, a thin catheter is introduced into the femoral artery at the groin and then flexibly steered through the blood vessels of the body to the artery involved in the aneurysm. This procedure is performed in an angiography suite. X-ray imaging allows the neurosurgeon to view the vessels via a solution containing water and iodine salts ("contrast"), which is injected through the catheter. The X-ray images provide detailed pictures of the location, size and shape of the aneurysm.

These questions are considered by the angiographer during the viewing procedure

  1. Is there an aneurysm?
  2. What is the exact location of the aneurysm?
  3. Is there one aneurysm or more than one?
  4. If there is more than one aneurysm, which one bled or is likely to bleed in the future?
  5. What is the size of the aneurysm?
  6. From what vessel is the aneurysm arising?
  7. Does the aneurysm have a neck, and what is the orientation of the neck and the dome?
  8. What is the ratio of the neck to the dome?
  9. What is the relationship of branch vessels to the aneurysm?
  10. What is the status of the circle of Willis?
  11. Is any other lesion associated with the aneurysm (e.g. extracranial occlusive vascular disease, vasculitis, AVM)?
  12. Is there vasospasm?

Aneurysm Treatment Options

Surgical Clipping

To access the aneurysm, the neurosurgeon first removes a section of the skull in a procedure called a craniotomy. Once the aneurysm is located within the brain tissue, a tiny clip is placed across the neck of the aneurysm to isolate it from normal circulation. The clip is similar to a coil-spring clothespin, in that the clip blades remain closed until pressure is applied to open the clip. Once the clip is secured to the aneurysm, the surgeon secures the bone to its original location and closes the incision. The titanium clips remain on the aneurysm permanently.

Endovascular Coiling

Endovascular coiling is a minimally invasive approach that does not include open surgery. Instead, the endovascular neurosurgeon uses fluoroscopic imaging, a type of real-time X-ray technology, to view the patient's vascular system and place coils within the aneurysm from within the blood vessel. Endovascular treatment of brain aneurysms involves insertion of a catheter into the femoral artery and navigating it through the vascular system into the head and into the aneurysm. Tiny platinum coils are threaded through the catheter to fill the aneurysm, blocking blood flow into the aneurysm and preventing rupture. This endovascular coiling (filling) of the aneurysm is called embolization.

"Should an aneurysm be clipped or coiled?" is a common question in the treatment of aneurysms. Occasionally, aneurysms are too complex in shape or too inundated with feeding arteries to be treated with a clip. In other cases, aneurysms are so hidden by complicated, sharp curving vasculature that a catheter cannot safely access the aneurysm for coiling. In such situations, the decision as to whether to clip or coil is clearly determined. In aneurysms without clear limiting factors for clipping or coiling, the treatment answer requires specific attention to the details of each presenting aneurysm.

A randomized, multi-centered trial recently compared the safety and efficiency of endovascular coiling with surgical clipping for aneurysms judged to be suitable for both treatments. This trial, the International Subarachnoid Aneurysm Trial (ISAT), found that the outcome in terms of survival and disability at one year is significantly better with endovascular coiling. The data available to date suggest that the long-term risks of further bleeding from the treated aneurysms are low with either therapy, although somewhat more frequent with endovascular coiling. The published results of the ISAT trial are taken into consideration when determining the most appropriate means of treatment for aneurysms.


Should I have surgery on my unruptured aneurysm?

Dr. William Thorell, M.D., an endovascular neurosurgeon at the University of Nebraska Medical Center, is committed to providing careful counseling for the patient and family regarding the risks and benefits of treatment. The size, shape and location of each aneurysm influence the surgical outcome. Certain aneurysms present with features which make the risk of surgical correction greater than leaving the aneurysm untreated. Furthermore, patient-related factors such as age and medical conditions have an influence on the likely outcome of treatment. Since scientific studies have not yet quantified every aspect of aneurysm intervention, the staff at The Nebraska Medical Center believes in providing individualized assistance to each patient considering treatment.

How long will it take to coil or clip my aneurysm?

Approximately four hours are needed to clip or coil. Based on the unique presenting factor of each aneurysm, some procedures take more time, whereas other procedures take less.

Will I be awake for the procedures?


After surgery, when will I be able to resume my normal daily activities?

Patients who have undergone coiling of an unruptured aneurysm usually return to normal daily activities within one week. Patients who have undergone clipping of an unruptured aneurysm usually return to normal daily activities within one month.

I have additional questions about my aneurysm. How can I find answers?

The Department of Neurosurgery at the University of Nebraska Medical Center is eager to respond to your health care concerns. Please call 402-559-3995 with any questions related to your aneurysm. We would be happy to suggest additional reading materials or provide direct answers to your questions.


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