Subarachnoid hemorrhage is defined as a rupture of a blood vessel in the cerebral base or superficial parts of the brain, with blood entering directly into the subarachnoid space. Any cause that can cause cerebral hemorrhage can also cause this disease, but intracranial aneurysm, arteriovenous malformation, hypertensive arteriosclerosis, anomalous vascular network at the base of the brain (moya-moya disease) and blood disorders are the most common. The disease mostly develops during emotional stress or excessive exertion. Aneurysms are more common. Aneurysm is not really a tumor, but a bubble that bulges out of the wall of a blood vessel like a balloon for various reasons, and its greatest danger is rupture and bleeding, which often leads to death. Clinical manifestations: It can develop at all ages, but is more common in young adults. Most of them occur acutely in emotional excitement or under exertion, and some patients may have a history of recurrent headaches. 1. Headache and vomiting: sudden onset of severe headache, vomiting, pale face and cold sweat. If the headache is limited to a certain place, it has localization significance, such as anterior headache suggesting supratentorial and cerebral hemispheres (unilateral pain), and posterior headache indicating posterior cranial recess lesion. 2. Disorders of consciousness and psychiatric symptoms: Most patients do not have disorders of consciousness, but may have irritability. In critical cases, there may be delirium, varying degrees of unconsciousness and coma, and a few may have seizures and psychiatric symptoms. 3. Meningeal irritation sign: It is common and obvious in young and middle-aged patients, accompanied by neck and back pain. Elderly patients, early hemorrhage or those in deep coma may not have meningeal irritation signs. 4. Other clinical symptoms: such as low fever, low back and leg pain, etc. Light hemiparesis, visual impairment, cranial nerve paralysis of III, V, VI and VII, retinal lamellar hemorrhage and optic papillar edema may also be seen. It can also be complicated by upper gastrointestinal bleeding and respiratory tract infection.