Intracranial aneurysms are abnormal bulges in the walls of cerebral arteries and are the most common cause of spontaneous subarachnoid hemorrhage (85% of spontaneous subarachnoid hemorrhages). The etiology is not well understood, but congenital aneurysms account for the majority of cases. It can occur at any age, but is common in 40-66 years old. 80% of the cases occur in the anterior part of the basilar artery ring. Clinically, it is characterized by focal symptoms such as spontaneous cerebral hemorrhage, cerebral vasospasm, and motor nerve palsy. Aneurysm “rupture” is often the main cause of severe symptoms and even death. According to statistics, after the first rupture of an aneurysm, the mortality rate is as high as 30-40%, half of which die within 48 hours after the onset of the disease, and 1/3 of the surviving cases may experience rebleeding. Cerebral angiography is the most accurate auxiliary diagnostic method, and whole brain angiography should be performed.CT scan can sometimes show aneurysmal lesions. CT scan can sometimes show the aneurysm lesion, and MRI examination can not only show the aneurysm, but also sometimes can see the attached thrombus. Once diagnosed as cerebral aneurysm, surgical treatment should be adopted in order to seek radical cure and avoid the danger of hemorrhage. Due to the great improvement of diagnosis, surgery and other treatment means, many parts of the aneurysm can achieve good results. Clinical manifestations 1. Symptoms of rupture and bleeding of aneurysm: if a medium or small aneurysm does not rupture and bleed, there may not be any clinical symptoms. Once the aneurysm ruptures and bleeds, the clinical manifestation is severe subarachnoid hemorrhage with rapid onset and severe headache, which is described as “the head is going to explode”. Frequent vomiting, profuse sweating, body temperature may be elevated; neck stiffness, Kirschner’s sign is positive. There may also be impaired consciousness or even coma. Some patients have triggers such as exertion and emotional excitement before bleeding, while others have no obvious triggers or develop in sleep. In about 1/3 of patients, aneurysm rupture is followed by death due to lack of timely diagnosis and treatment. Most aneurysm rupture will be closed by coagulation and bleeding will stop, and the condition will be gradually stabilized. As the blood clot around the aneurysm rupture dissolves, the aneurysm may rupture again and bleed. Secondary hemorrhage usually occurs within 2 weeks of the first hemorrhage. In some patients, the hemorrhage may invade the vitreous humor through the optic nerve sheath and cause visual impairment. After subarachnoid hemorrhage, the destruction of red blood cells produces 5-hydroxytryptamine, catecholamines and other vasoactive substances that act on the cerebral blood vessels, and vasospasm occurs, the incidence of which is 21% to 62%, and it occurs mostly in the 3-15 days after hemorrhage. Localized vasospasm occurs only in the vicinity of the aneurysm, and the patient’s symptoms are not obvious and only show up on cerebral angiography. Widespread cerebral vasospasm will lead to cerebral infarction, patient’s consciousness disorder, hemiplegia, and even death. 2.Focal symptoms: it depends on the location of the aneurysm, the adjacent anatomical structure and the size of the aneurysm. Motor nerve palsy is common in internal carotid artery – posterior communicating artery aneurysm and aneurysm of posterior cerebral artery, which manifests as unilateral eyelid ptosis, pupil dilatation, inward, upward and downward vision inability, and disappearance of direct and indirect light reaction. Sometimes focal symptoms appear before subarachnoid hemorrhage, which is regarded as the precursor symptom of aneurysm hemorrhage, such as mild migraine, orbital pain, followed by paresthesia of the motor nerve, which should be alerted to the ensuing subarachnoid hemorrhage. Aneurysm hemorrhage of the middle cerebral artery such as the formation of hematoma; or other parts of the aneurysm hemorrhage, cerebral vasospasm cerebral infarction, the patient may appear hemiplegia, motor or sensory aphasia. Giant aneurysm affecting the visual pathway, the patient may have visual field obstruction. After aneurysm hemorrhage, the severity of the condition varies. In order to facilitate the judgment of the condition, choose the timing of imaging and surgery, and evaluate the efficacy. Diagnostic examination 1. Determine whether there is subarachnoid hemorrhage. In the acute stage of hemorrhage, CT confirms the positive rate of SAH, which is safe, rapid and reliable. After one week of bleeding, CT is not easy to diagnose. Lumbar puncture may induce aneurysm rupture and hemorrhage, so it is no longer generally used as the first choice to confirm the diagnosis of SAH. 2.Because intracranial aneurysms are mostly located in the WiLLis arterial ring at the base of the skull, aneurysms with a diameter of less than 1.0C are not easily detected by CT. If the diameter is larger than 1.0cm, it can be detected by CT scan after injection of contrast agent, and MRI is worse than CT, and the aneurysm can be seen to be flowing inside the aneurysm, and MRA can suggest aneurysms in different parts of the body, which is often used for screening of intracranial aneurysms. Three-dimensional CT (3D-CT) can understand the relationship between the aneurysm and the aneurysm-carrying artery from different angles, and provide more information for the decision-making of surgical clamping of aneurysm. 3.Cerebral angiography is a necessary examination method to confirm the diagnosis of intracranial aneurysm, which is very important for determining the exact location, morphology, internal diameter, number, vasospasm and surgical plan of the aneurysm. Total cerebral angiography via femoral artery cannulation can avoid missing multiple aneurysms. Early imaging to clarify the diagnosis and surgical clamping of the aneurysm as soon as possible can prevent the aneurysm from rupturing and bleeding again. If the first imaging is negative, the aneurysm may not be visualized due to cerebral vasospasm, and the aneurysm is highly suspected, the imaging should be repeated after 3 months. Treatment There are two main methods: craniotomy aneurysm neck clamping and interventional embolization. So far, there is no third more effective treatment method at home and abroad. Isolated surgery should not be used as a last resort, while the efficacy of encapsulation is difficult to determine. Craniotomy: After craniotomy, the aneurysm is separated under the microscope and clamped, but it is easy to cause hemorrhage of the aneurysm when clamping and it is more risky to perform deep aneurysm surgery, and the patient’s recovery after the surgery is relatively slow. Interventional embolization: Craniotomy is more traumatic, in the 90s, a new technique of detachable spring coil embolization was carried out for the treatment of intracranial aneurysms. The spring coil is made of platinum, which is guided by a microcatheter and introduced into the spring coil to block the aneurysm, which is excellent in operability and safety, and is now popularized and applied in the clinic, and the spring coil is very thin, like a hair. Considering all factors, the most suitable individualized treatment plan will be developed for the patient, so that the best treatment effect can be achieved at the lowest cost. Remember, when an aneurysm bleeds for the first time, it may get better with internal medicine treatment, but it is important to grasp the timing and treat the underlying cause of the disease, and not to wait and see, so as not to lose the opportunity.