Primary subarachnoid hemorrhage (SAH) refers to the flow of blood into the subarachnoid space after the rupture of a blood vessel on the surface of the brain. The annual incidence is 5-20/100,000, and the common causes are intracranial aneurysm, followed by cerebrovascular malformation, hypertensive atherosclerosis, arteritis, anomalous vascular network at the base of the brain, connective tissue disease, hematologic disease, and complications of anticoagulation therapy. The clinical manifestations of subarachnoid hemorrhage mainly depend on the amount of hemorrhage, the site of blood accumulation, and the degree of cerebrospinal fluid circulation impairment. 1.Onset of the disease: Most of them have an acute onset under emotional or exertional conditions. 2.Main symptoms: sudden onset of severe headache, persistent unrelieved or progressive aggravation; mostly accompanied by nausea and vomiting; there may be transient disorders of consciousness and mental symptoms such as irritability and delirium, and a few appear seizures. 3.Main signs: meningeal irritation signs are obvious, subfoveal hemorrhage can be seen in the fundus, and a few may have signs of focal neurological deficits, such as mild hemiparesis, aphasia, and actinic nerve palsy. (1) Generally, Hunt and Hess grading method is used to grade the clinical status of aneurysmal SAH in order to select the timing of surgery and judge the prognosis.