1. Symptoms of unruptured aneurysm If the medium-sized or small aneurysm has not ruptured and bled, there may not be any clinical symptoms. 2. Symptoms of aneurysm rupture and hemorrhage Once the aneurysm ruptures and hemorrhages, there will be severe subarachnoid hemorrhage or even intracranial hematoma, which will be acute in onset, and the patient will have a severe headache, which is intolerable, such as “the head is going to be blown up” in general. Frequent vomiting, profuse sweating, body temperature may be elevated; cervical rigidity, 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 hemorrhage, while some have no obvious triggers or develop in sleep. After aneurysm bleeding, the severity of the condition varies. In about 1/3 of the patients, aneurysm rupture and death due to the lack of timely diagnosis and treatment. In most cases, the aneurysm rupture is closed by clotting and bleeding stops, and the condition stabilizes gradually. 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 erythrocytes produces 5-hydroxytryptamine, catecholamines and other vasoactive substances that act on the cerebral blood vessels, and vasospasm occurs, with an incidence of 21%-62%, most often occurring 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. Focal symptoms depend 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 posterior cerebral artery aneurysm, which manifests as unilateral eyelid ptosis, pupil dilatation, inward, upward and downward vision, 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, and then we should be alert 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 hemiparesis, motor or sensory aphasia. Giant aneurysms affecting the visual pathway, patients may have visual field impairment.