A brain aneurysm (cerebral aneurysm) is a bulge arising from the side of an artery wall in the head. It may be present from birth or develop after injury to the blood vessel. It has been estimated that up to about 5% of the population has a cerebral aneurysm. Symptoms of an aneurysm can include headaches or focal neurological deficits (such as a cranial nerve injury leading to difficulty with eye movement). Although rupture of an aneurysm is uncommon, the bleeding into the space surrounding the brain known as subarachnoid hemorrhage causes a severe headache and carries a high risk of severe neurologic injury and death. Risk factors for cerebral aneurysm growth include a family history, smoking, high blood pressure, and certain medical problems including polycystic kidney disease. Unruptured aneurysm treatment varies depending on several factors including the aneurysm shape, location, and a patient’s overall health. Management strategies include observation, endovascular coil embolization or blood flow diversion, and microsurgical clipping. A ruptured cerebral aneurysm is an emergency that requires urgent treatment.