In layman’s terms, an aneurysm is a localized enlargement of the wall of a blood vessel, resembling a balloon, which is filled with blood. Intracranial aneurysms are aneurysm-like structures that occur in the walls of intracranial vessels, most often in the willis ring of the skull. Due to the specificity of cerebral vascular anatomy and hemodynamic reasons, the intracranial arterial system is more prone to aneurysm than the extracranial arteries. Guilin Li, Department of Neurosurgery, Xuanwu Hospital, Capital Medical University When an aneurysm increases in size, its risk of rupture also increases. Scientific studies have found that the annual rupture rate of <5 mm< font=""> unruptured aneurysms in the anterior circulation is 0, with a 0.3% risk of re-rupture for those with a history of previous rupture; 0.5% for 5-12 mm aneurysms; 3% for 13-24 mm aneurysms, and up to 8% for giant aneurysms. The overall rupture rate of posterior circulation aneurysms was higher than that of anterior circulation. The annual rupture rate is 0.5% for unruptured aneurysms <5mm< font=""> and 0.7% for those that have bled; 3% for 5-12mm aneurysms; 3.7% for 13-24mm; and up to 10% for giant aneurysms. It is well known that bleeding from ruptured aneurysms is often fatal. When an intracranial aneurysm ruptures and bleeds, about half of the patients will die. Therefore, the node of treatment for aneurysm lies in the time of its rupture, and treatment before then is effective to avoid aneurysm rupture and save patients’ lives. Once the aneurysm has ruptured, treatment is less effective, with some neurological deficits remaining in mild cases, and even in severe cases, the patient’s life cannot be saved. However, some aneurysms do exist that do not rupture for life and do not have any pathological impact on the patient, so the question of whether and when to treat any incidentally discovered aneurysm is a clinical issue that needs to be addressed.
To address this issue, the cause of the ruptured aneurysm must first be identified. Previous studies have found that the susceptibility of an aneurysm to rupture depends primarily on the structural fragility of the aneurysm wall and the altered hemodynamics within the aneurysm. The physician’s assessment of the risk of rupture of a particular unruptured aneurysm, or the decision to treat it, relies more heavily on knowledge of the structural characteristics, morphologic changes, and hemodynamic effects of the aneurysm. These images show the morphology of intracranial aneurysms, the direction, velocity, and status of blood flow within the aneurysm and its carrier artery, and the magnitude of the effect of blood flow on the vessel wall. These studies allow physicians to predict the risk of aneurysm rupture in general and thus guide treatment. The most accurate and reliable way to obtain this information, given the current state of medical development, is to perform a cerebral angiogram (DSA). Through cerebral angiography, imaging features of the aneurysm and its associated environment are obtained, while computer processing is performed for hemodynamic conversion and ultimately for prediction of the risk of aneurysm rupture. Therefore, for incidentally detected aneurysms, it becomes very necessary to perform periodic cerebral angiography to observe the evolution of aneurysm characteristics. If the change is not significant, the observation can be continued; if it is significant, especially within a short period of time, it is a high warning of aneurysm rupture and needs to be treated as soon as possible in order to minimize the risk before it ruptures and thus safely and effectively protect the patient’s life.