An aneurysm is an abnormal bulge or ballooning in the wall of a blood vessel, typically caused by a weakened area in the vessel wall. This weakening can occur due to factors like high blood pressure, atherosclerosis (hardening of the arteries), genetic predispositions, and trauma. Common sites for aneurysms include the brain (cerebral aneurysm), the main artery from the heart (aortic aneurysm), and arteries in other parts of the body like the legs or spleen.

Aneurysms are concerning because they can rupture, leading to life-threatening internal bleeding. For instance, a ruptured cerebral aneurysm causes a hemorrhagic stroke, which may result in severe neurological impairment or death if not treated immediately. Unruptured aneurysms, on the other hand, often show no symptoms and may go undetected unless discovered incidentally during imaging for other reasons.

Treatment depends on the aneurysm's size, location, and risk of rupture. Options include monitoring small, low-risk aneurysms or performing surgery for larger, high-risk aneurysms. Surgical interventions may involve clipping (placing a clip at the aneurysm base) or coiling (filling the aneurysm with coils to prevent blood flow). Preventing aneurysm complications involves managing blood pressure, avoiding smoking, and regularly monitoring individuals at higher risk.