1.What is an aneurysm? Intracranial aneurysm is a cerebral vascular aneurysm-like protrusion produced by abnormal local vascular changes in the cerebral arteries. The incidence of intracranial aneurysm is second only to cerebral infarction and hypertensive cerebral hemorrhage, and is one of the main causes of spontaneous subarachnoid hemorrhage in patients with cerebrovascular disease. 2.What is the etiology of aneurysm formation? Congenital, atherosclerosis, traumatic and infectious, etc. What are the symptoms after aneurysm rupture? The typical clinical manifestations after aneurysm rupture are sudden severe headache, vomiting, neck stiffness, irritability, followed by transient impairment of consciousness and various neurological deficits of different degrees and systemic symptoms. Some patients have atypical symptoms after rupture of aneurysm, only cranial nerve disorder, such as oculogyric nerve palsy, slow onset, not like subarachnoid hemorrhage. 3.How to diagnose aneurysm （1）CT examination: The detection rate of intracranial aneurysm by CT scan is not high, and it can only determine the extent of bleeding, the size of hematoma and cerebral infarction. (2) MRI: MRI or MRA can show the whole aneurysm and its relationship with the surrounding area, and the thrombus and blood flow part inside the aneurysm can also be shown. Its detection rate is significantly higher than that of CT scan. However, the limitation of MRI is that it cannot diagnose internal bleeding and subarachnoid hemorrhage at an early stage. (3) Cerebral angiography (DSA): The final diagnosis of intracranial aneurysm depends on cerebral angiography. Cerebral angiography can show the location, size, shape and number of aneurysms, the presence or absence of thrombus in the sac, the extent and degree of arteriosclerosis and spasm, the presence or absence of intracranial hematoma or hydrocephalus, the width and narrowness of the aneurysm tip and whether it is suitable for surgical clamping or embolization treatment, etc. (4) CTA: It can show the morphology of aneurysm and its relationship with the surrounding area in a visual and three-dimensional way without trauma. 4.How to treat aneurysm? Patients with aneurysm, after the rupture and bleeding of aneurysm, visit the doctor with symptoms such as headache and vomiting, and are diagnosed with subarachnoid hemorrhage by CT. Before the patient’s final diagnosis is clear, the patient needs to be treated routinely, such as stopping bleeding, lowering blood pressure, lowering cranial pressure, etc. The main methods of surgical treatment for aneurysm are currently: craniotomy – clamping of aneurysm, endovascular treatment – aneurysm embolization. Aneurysms clearly diagnosed by cerebral angiography roar, usually need surgical treatment, there is still a possibility of aneurysm re-rupture and bleeding and life-threatening.