Cerebral aneurysms can develop at any age and are more common in women than in men between the ages of 40 and 60. They are most often found in the arterial ring (Willis ring) at the base of the brain. The causes of cerebral aneurysms are not well understood, but may be related to the following causes: ① congenital weakness of cerebral vascular wall structure; ② long-term hypertensive blood flow shock; ③ degenerative changes of cerebral vascular wall structure caused by smoking and diabetes. Brain aneurysm is not a real tumor, but an abnormal local expansion of arterial blood vessels, just like the inner tube of a bicycle suddenly bulges up when it is over-inflated, the final result of the bulging inner tube is an explosion, and the final result of brain aneurysm is also an explosion and rupture. Once a brain aneurysm is formed, it will not disappear on its own, but will grow and expand gradually under the impact of blood pressure, and people with high blood pressure are more likely to have aneurysm expansion and rupture. The size of cerebral aneurysms varies widely, with aneurysms usually ranging from 5 to 20 mm in diameter, and the rupture of an aneurysm is related to its size, with ruptured aneurysms generally being larger and unruptured ones smaller. The critical size for cerebral aneurysm rupture is 5-6 mm in diameter, and the chance of rupture and bleeding increases gradually for aneurysms over 5 mm in diameter. Yellow people have the highest incidence of cerebral aneurysms. Modern imaging studies show that about 90% of subarachnoid hemorrhages are due to ruptured cerebral aneurysms. Subarachnoid hemorrhage caused by ruptured cerebral aneurysms is the third most common cerebrovascular accident, after cerebral thrombosis, cerebral infarction and hypertensive intracerebral hemorrhage. Most ruptured cerebral aneurysms are caused by massive jet hemorrhage from the aneurysm. Patients often fall into coma within minutes to hours, and in severe cases, the brainstem is stimulated by pressure and rapid death from respiratory and cardiac arrest. The first rupture and bleeding of cerebral aneurysm will cause death or severe disability in half of the patients, the second rupture and bleeding will double the rate of death and severe disability, and if the third rupture and bleeding occurs, there are almost no healthy survivors or survivors. Therefore, once a cerebral aneurysm ruptures and bleeds, the patient should be transferred to a hospital with conditions to eliminate the aneurysm as soon as possible. In order to save the patient’s life and restore the patient’s health. Most of them are detected only when the cerebral aneurysm ruptures and bleeds, causing subarachnoid hemorrhage, and the patient suddenly develops a severe headache and impaired consciousness as the most common manifestation. Before a ruptured cerebral aneurysm bleeds, 90% of patients have no obvious symptoms and signs. In a few patients, the aneurysm grows to compress the adjacent cerebral nerves and produces special manifestations, such as posterior communicating aneurysm compressing the ophthalmic nerve and causing one eye to open. The rupture of cerebral aneurysm is usually caused by a sudden and violent increase in arterial blood pressure, such as coughing, sneezing, anger, happy laughter, forceful urination and defecation, late pregnancy, childbirth, physical labor, sexual life, etc., which induces aneurysm rupture. After an aneurysm ruptures and bleeds, the bleeding is stopped temporarily by clotting and vasospastic contraction of the blood vessels. One to two weeks after bleeding, auto-fibrinolysis and thrombolysis are hyperactive, resulting in liquefaction of the clot at the ruptured cerebral aneurysm, and the ruptured aneurysm will hemorrhage again in nearly 20% to 50% of patients within one month. The rebleeding leads to a doubling of the mortality and severe disability of the patient.