With the development of medical imaging techniques, the detection rate of unruptured intracranial aneurysms is increasing. Because of the potential risk of subarachnoid hemorrhage caused by unruptured aneurysms and the high mortality and disability rates following subarachnoid hemorrhage, and because the interventional treatments currently used, including surgical treatment and endovascular treatment, have the same mortality and disability rates, the treatment or non-treatment of unruptured aneurysms is receiving increasing attention. This article reviews the risks of bleeding and treatment of unruptured aneurysms in the hope of suggesting better management strategies for unruptured aneurysms. 1. The risk of bleeding from ruptured unruptured aneurysms. The rate of subarachnoid hemorrhage from unruptured aneurysms varies widely, and Juvela concluded that the cumulative incidence of subarachnoid hemorrhage from unruptured aneurysms was 10.5% at 10 years, 23% at 20 years, and 30.3% at 30 years with a mean follow-up of 19.7 years (0.8-38.9 years). Mortality after ruptured aneurysm hemorrhage accounts for approximately 1.2% of all follow-ups. the Rinkel et al. study suggested a 1.9% annual rate of subarachnoid hemorrhage from unruptured aneurysms. There are many factors that influence ruptured bleeding from unruptured aneurysms. Currently, the more certain factors are aneurysm size, location, patient age, blood pressure, and smoking history. (1) Size of aneurysm: The size of the aneurysm is one of the most important factors in the occurrence of subarachnoid hemorrhage in unruptured aneurysms, which has been unanimously recognized. The annual rupture rate for aneurysms larger than 10 mm was 2.8%. (2) Location of aneurysm: Aneurysms in the posterior circulation are more likely to rupture and bleed than aneurysms in other locations. 50%, which are significantly different from the anterior circulation. (3), the patient’s age: the older the patient is, the greater the likelihood of ruptured bleeding from unruptured aneurysms. wiebers believes that patients older than 59 years old have twice the risk of ruptured bleeding than younger patients. (4), blood pressure factor: Hypertensive patients are high hemodynamic, which can affect not only the formation of aneurysm, but also the rupture bleeding of aneurysm. Juvela studied 142 patients with unruptured aneurysm, among which, 8 cases of bleeding occurred in 30 hypertensive patients (27%) and 24 cases of bleeding occurred in 111 non-hypertensive patients (22%), which is not statistically significant. However, the mean blood pressure was 148±11/92±8 mmHg in patients with fatal subarachnoid hemorrhage and 135±15/83±11 mmHg in non-fatal subarachnoid hemorrhage, while there was statistical significance, indicating the importance of hypertension in patients with fatal subarachnoid hemorrhage. (5), Smoking factors: Studies have shown that smoking can affect aneurysm formation, aneurysm growth, and also aneurysm rupture. Several surveys have shown that in North America and Europe, smokers are more likely to have aneurysmal subarachnoid hemorrhage than non-smokers, with the former being about twice as likely as the latter. In general, smokers have lower blood pressure than nonsmokers, but smoking can cause a transient increase in blood pressure, and it can cause pathological changes in the blood vessel walls and can lead to the development of vasospasm. (6) Other factors: Female patients have a higher chance of aneurysm rupture and bleeding than male patients. Foliated aneurysms are more likely to rupture than regular aneurysms. Symptomatic aneurysms are more likely to rupture than asymptomatic aneurysms. Multiple aneurysms are more likely to rupture than single aneurysms, and if an aneurysm has previously ruptured, the likelihood of rupture of other unruptured aneurysms is greatly increased. During pregnancy and childbirth, aneurysms are more likely to rupture. 2. Risks of treatment of unruptured aneurysms. (1) The risk of craniotomy. Craniotomy is the more classical method to treat intracranial aneurysm. The most ideal method is aneurysm neck clamping, other methods such as isolation, aneurysm wall reinforcement, isolation + bypass surgery, etc. All treatments are associated with certain mortality and disability rates. According to the bulk of statistics, the overall mortality and disability rates for craniotomy are 0-5% and 2-17%. 2460 patients were analyzed by Raaymakers, and the mortality and disability rates were 2.6% and 10.9%, respectively. Christopher’s analysis of 604 unruptured aneurysms in 481 patients showed that 98% of young patients with aneurysms of 5-10 mm in diameter located in the anterior circulation had good results with surgery, but For aneurysms located in the posterior circulation and with a diameter of about 10 mm, 97% of patients had a good prognosis if they were about 45 years old, while only 86% of patients had a good prognosis if they were about 65 years old. The differences in statistical results are related to regional differences, the number of statistical cases and artificial data screening, as well as to the surgical approach and surgical technique. In recent years, there has been an overall decreasing trend in reported surgical mortality and disability rates. There are many factors that influence the outcome of surgery for unruptured aneurysms, the four most common influences being the age of the patient, the size of the aneurysm, the location of the aneurysm, and the overall quality of the medical unit, medical and nursing staff. Khanna classifies patients according to their age, aneurysm size and site, with age groups classified as less than 40 years old, 40-60 years old and more than 60 years old, aneurysm size classified as less than 10 mm, 10-25 mm and more than 25 mm, and the site of aneurysm was classified as simple anterior circulation aneurysm, complex anterior circulation aneurysm, simple posterior circulation and complex posterior circulation aneurysm. The overall mortality and disability rates for aneurysm surgery increased from about 0% to 66.6% from grade 0 to grade 6. Christopher used multiple regression analysis to show the relationship between the outcome of unruptured aneurysm surgery and the patient’s age, size of the aneurysm, and site of the aneurysm, revealing the correlation between the outcome of unruptured aneurysm surgery and these three. The overall quality of the medical unit, medical and nursing staff is also one of the important factors affecting the outcome of surgery. (2), the risk of endovascular treatment. In recent years, endovascular treatment of unruptured aneurysms has been developed considerably, especially the application of electrolytic detachable spring coils, which has become one of the important means of treating unruptured aneurysms. In unruptured aneurysms, the aim of endovascular treatment is to occlude the aneurysmal lumen or the aneurysm-carrying artery, thereby preventing the occurrence of subarachnoid hemorrhage. Of the 4060 patients with unruptured intracranial aneurysms followed by Wieber et al, 1692 were untreated, 1917 were treated surgically, and 451 were treated endovascularly, and found that the disability rate following rupture and bleeding from untreated aneurysms was slightly higher than the disability rate from surgical treatment and endovascular treatment. He also suggested that the main factors affecting the efficacy of endovascular treatment were the size and location of the aneurysm and the age of the patient.1 Brilstra1 investigated 1383 patients with unruptured aneurysms treated endovascularly and found that the permanent complications of endovascular treatment were 3.7%.2 Barker reviewed the endovascular treatment of 421 unruptured aneurysms and found that the mortality rate of endovascular treatment The mortality rate was about 1.7% and the disability rate was about 7%, which was lower than that of patients treated with open surgery, but not statistically significant. As endovascular treatment techniques become more sophisticated, the mortality and disability rates for endovascular treatment of unruptured aneurysms are gradually decreasing. My study shows that for elderly patients, endovascular intervention has obvious advantages over craniotomy. 3. Strategies of treatment. (1), whether to receive treatment or not. There is no uniform standard whether to treat unruptured aneurysm or not. Juvela believes that patients with unruptured aneurysms less than 10 mm in diameter should be considered for treatment if they are less than 60 years of age and have no contraindications. The patient should be considered for treatment if there are no contraindications. Patients should be treated if they smoke, even if they are older than 60, because smoking accelerates aneurysm growth and triggers aneurysm rupture and bleeding. Panigrahi believes that treatment should be strongly recommended if the aneurysm growth rate exceeds 0.95 mm per year. (2) Selectivity of treatment methods. The mortality and disability rates of endovascular treatment of unruptured aneurysms are lower than those of patients treated surgically, and the vast majority of scholars accept this concept. According to Barker, the mortality and permanent disability rates for surgical treatment are not statistically significant when compared to endovascular treatment, however, when considering the near-term disability rate of treatment, surgical treatment is significantly greater than endovascular treatment. The goal of endovascular treatment of unruptured aneurysms is to prevent aneurysm rupture and bleeding, which is prevented by complete occlusion of the aneurysm or the aneurysm-carrying artery and altering the natural history of the unruptured aneurysm. However, electrolytic detachable spring coils have only been in use since 1991, so its long-term efficacy in preventing rebleeding of unruptured aneurysms needs to be summarized by long-term follow-up. The choice of treatment is based on a combination of patient age, coexisting other diseases, the site of the aneurysm, patient requirements, and the technical factors of the treatment group. The most important factors are the patient’s age and other coexisting diseases. If the patient is older than 65 years, endovascular treatment is clearly superior to surgical treatment, and this superiority is even more evident when other coexisting diseases are considered. In addition to the above considerations, the skill of the medical unit and the medical staff is also important in the choice of treatment for unruptured aneurysms, and Hoh suggests that interventional treatment by highly qualified medical groups and units has significantly lower mortality and permanent disability rates than the average medical unit, as well as significantly lower hospital costs and days. Interventional treatment protocols should also be integrated with the treatment characteristics of the medical group. Medical groups that specialize in surgical treatment will prefer surgical treatment, whereas medical groups with a predominance of endovascular treatment techniques will be more interested in endovascular treatment. Open surgical treatment and endovascular treatment are not independent treatment measures, they should be complementary. 4. concluding remarks. There are many factors affecting the rupture and treatment of unruptured aneurysms, and there is no uniform standard for the management of unruptured aneurysms, and the “risk-benefit ratio” needs to be weighed. The treatment of unruptured aneurysms requires further data summarization, especially in China, where there is a lack of data on unruptured aneurysms in large numbers. In recent years, endovascular treatment has been carried out, but there is a problem of incomplete occlusion of the aneurysm lumen, and it is necessary to understand the rebleeding after endovascular treatment, therefore, the follow-up data need to be further accumulated and the follow-up time needs to be further extended.