Fusiform Aneurysm

What Is It, Causes, Treatment, and More

Author:Georgina Tiarks

Editors:Alyssa Haag,Józia McGowan, DO,Kelsey LaFayette, DNP, RN

Illustrator:Jessica Reynolds, MS

Copyeditor:David G. Walker

What is a fusiform aneurysm?

A fusiform aneurysm refers to an aneurysm that has a circumferential and ballooning shape. An aneurysm occurs when a portion of blood vessel walls becomes weak and subsequently dilates. In order to be classified as an aneurysm, the wall must balloon to more than 50% of its normal diameter. There are many different types of aneurysms based on their shape, including fusiform, saccular (i.e., berry), and mycotic. Fusiform shaped aneurysms balloon outward on all sides. Comparatively, a saccular aneurysm only bulges on one side and is associated with congenital conditions such as autosomal dominant polycystic kidney disease (i.e., a cystic kidney disorder), Ehlers-Danlos syndrome (i.e., a condition affecting collagen synthesis), and Marfan syndrome (i.e., a condition affecting connective tissue) as well as hypertension (i.e., elevated blood pressure), smoking, and advanced age. On the other hand, a mycotic aneurysm is mushroom-shaped and commonly the result of an infection.

Aneurysms can also be classified based on which layers of the blood vessel wall are involved. Blood vessels are made up of three separate layers: the tunica intima, tunica media, and tunica externa (i.e., tunica adventitia). A true aneurysm is a dilation of all the layers of the vessel wall. With a pseudoaneurysm, also known as a false aneurysm, however, the inner two layers of the vessel wall break while the tunica adventitia stays intact, thereby allowing blood to pool between the media and adventitia. Finally, a dissecting aneurysm occurs when there is a tear in the tunica intima, and the layers of the vessel wall separate.

Image of an abdominal aorta bursting with blood due to a fusiform aneurysm.

Is a fusiform aneurysm serious?

Yes, fusiform aneurysms can be serious. If they rupture, uncontrolled hemorrhaging (i.e., bleeding) may occur, which can be life threatening.

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What causes a fusiform aneurysm?

A fusiform aneurysm is caused by deterioration and weakening of the blood vessel wall, which may occur through various mechanisms. The most common mechanism is dissection, which results from stress or force on the vessel wall, causing a rupture of one of the layers and bleeding within the wall. Studies have proposed that atherosclerosis (i.e., lipid deposition) may play a role in this by weakening the internal elastic membrane within the tunica intima, which may also subsequently become a fusiform aneurysm. Disorders of elastin and collagen (e.g., Marfan syndrome and Ehlers-Danlos syndrome) have also been proposed as mechanisms of arterial wall disruption. In addition, certain infections, like syphilis, as well as pregnancy, smoking, hypertension, systemic lupus erythematosus, fibromuscular dysplasia, and trauma may also increase the risk of developing a fusiform aneurysm.

What are the signs and symptoms of a fusiform aneurysm?

The signs and symptoms of a fusiform aneurysm depend on the location of the aneurysm. A brain aneurysm, also known as cerebral or intracranial aneurysm, may present with severe headache, dizziness, loss of consciousness, or neurologic deficits due to mass effect. Mass effect occurs when the aneurysm puts pressure on an area of the brain and causes a specific neurologic problem. For example, the optic chiasm may be affected by an aneurysm, which can cause bitemporal hemianopsia (i.e., temporal vision loss). 

Conversely, an abdominal aortic aneurysm may cause pain or throbbing in the abdomen or chest and lower back pain. Similarly, a common iliac aneurysm may result in abdominal or groin pain. A healthcare provider may be able to feel a pulsating mass upon palpation or hear a blowing sound indicating abnormal blood flow (i.e., a bruit) upon auscultation of abdominal, common iliac, or femoral arteries, depending on the location of the aneurysm.

Other more non-specific symptoms may present, such as tachycardia (i.e., rapid heart rate), clammy skin, nausea, or vomiting. In some cases, however, an aneurysm may cause no symptoms.

How is a fusiform aneurysm diagnosed and treated?

A fusiform aneurysm should be attended to immediately as it can become life threatening. For aneurysms located at the abdomen, groin, or extremity, an ultrasound is often used initially to visualize and determine the size of the artery in question. If the aneurysm is large, the individual will often be referred directly for treatment. In other cases, a follow-up computer tomography angiography (i.e., CT angiography) may be used to confirm the diagnosis. Conversely, for a brain aneurysm, an angiography may be used to determine the size and location of the aneurysm within the brain.

Treatment of an abdominal, groin, or extremity aneurysm will depend on the severity, location, and individual symptoms. With small or asymptomatic aneurysms, conservative treatment may be utilized, which may include ultrasounds to assess for changes, blood pressure control, and management of any risk factors (e.g., smoking cessation or medication to lower cholesterol). Conversely, with aneurysms that have ruptured or are at severe risk of rupture (e.g., abdominal aneurysms larger than four centimeters and thoracic aneurysms larger than six centimeters), a repair may be warranted either through a stent insertion or open laparotomy. 

Similarly, with asymptomatic or unruptured intracranial aneurysms, conservative management, such as reduction of blood pressure and follow-up imaging, may be an option. Regular follow-up visits with a vascular surgeon or neurosurgeon may also be indicated. With ruptured or at-risk intracranial aneurysms, endovascular coiling or microvascular clipping may be employed to repair the aneurysm.

Preventative measures may also be used to discover aneurysms before they enlarge. In some cases, a one-time screening ultrasound may be recommended for men aged 65 to 75 years of age who have a history of smoking.

What are the most important facts to know about fusiform aneurysms?

A fusiform aneurysm is a type of aneurysm named according to its circumferential and ballooning shape. An aneurysm is a weakened area of a blood vessel wall. Fusiform aneurysms can be caused by atherosclerosis, connective tissue diseases, smoking, hypertension, infections, pregnancy, systemic lupus erythematosus, fibromuscular dysplasia, and trauma. The signs and symptoms of a fusiform aneurysm may differ depending on where the aneurysm is located. A cerebral aneurysm may present with headache, dizziness, and loss of consciousness. Meanwhile, an abdominal aneurysm may cause abdominal, back, or groin pain. Diagnosis often involves imaging studies, such as an ultrasound, CT with angiography, or cerebral angiography. The treatment of a fusiform aneurysm may depend on the severity. However, both conservative and surgical treatment are considered.  

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Resources for research and reference

Aneurysm. In Johns Hopkins Medicine. Retrieved December 9, 2021, from

Barletta, E. A., Ricci, R. L., Silva, R. D. G., Gaspar, R. H. M. L., Araújo, J. F. M., Neves, M. W. F., de Aquino, J. L. B., & Barba Belsuzarri, T. A. (2018). Fusiform aneurysms: A review from its pathogenesis to treatment options. Surgical Neurology International, 9: 189. DOI: 10.4103/sni.sni_133_18

Mohamed, M., & Rasuli, B. (2020). Fusiform intracranial aneurysm. In Radiopaedia. Retrieved December 10, 2021, from

Park, S.H., Yim, M.B., Lee, C.Y., Kim, E., & Son, E.I. (2008). Intracranial Fusiform Aneurysms: It’s Pathogenesis, Clinical Characteristics and Managements. Journal of Korean Neurosurgical Society, 44(3): 116–123. DOI: 10.3340/jkns.2008.44.3.116

Types of Aneurysms. (2021). In American Heart Association. Retrieved December 10, 2021, from