An aneurysm or aneurism (from Greek: ἀνεύρυσμα, aneurusma, “dilation”, from ἀνευρύνειν, aneurunein, “to dilate”) is a localized, blood-filled balloon-like bulge in the wall of a blood vessel.

Aneurysms can occur in any blood vessel with examples including aneurysms of the circle of Willis in the brain, aortic aneurysms affecting the thoracic aorta, and abdominal aortic aneurysms. Aneurysms can also occur within the heart itself. As an aneurysm increases in size, the risk of rupture increases.

A ruptured aneurysm can lead to bleeding and subsequent hypovolemic shock, leading to death. Aneurysms are a result of a weakened blood vessel wall, and can be a result of a hereditary condition or an acquired disease.

The most frequent location is the arterial bifurcation.

see Intracranial aneurysm.

Large, giant, wide-necked, fusiform aneurysms

Saccular aneurysm

Blister aneurysm

Coiled aneurysm

Dissecting aneurysm

Mirror aneurysms are a rare subtype of multiple aneurysms, located in identical or adjacent arterial segment bilaterally.

Mycotic aneurysm

Traumatic aneurysm

see Aneurysm morphology.

see Aneurysm size.

Dome

see Aneurysm etiology.

see Intracranial aneurysm pathogenesis.

Aneurysms associated with arteriovenous malformations (AVM) are well represented in the literature. Their exact etiology is poorly understood, but likely global hemodynamic changes coupled with vascular wall pathology play into their formation. Flow-related and intranidal aneurysms, in particular, appear to have an increased risk for hemorrhagic presentation. Treatment strategies for these aneurysms are particularly challenging ¹⁾.

Evolving endovascular technologies need to be integrated into the microsurgical management of aneurysms. Multimodality approaches are best used with complex aneurysms in which conventional therapy with a single modality has failed. Revascularization remains a unique surgical contribution to the overall management of aneurysms with which current endovascular techniques cannot be used. Multimodality management should be considered an elegant addition to the therapeutic armamentarium that, through simplification and increased safety, improves the treatment of complex aneurysms beyond what is achievable by performing clipping or coiling alone ²⁾.

Aneurysm model