The clinically used grading method for subarachnoid hemorrhage is the Hunt-Hess grading. There are five grades. Grade 1, patients may have no clinical symptoms or only mild symptoms of headache and meningeal irritation. Grade 2: Patients may show more obvious headache, nausea and vomiting, and more obvious signs of meningeal irritation and local cranial nerve dysfunction. Grade 3: Patients may exhibit blurred consciousness, drowsiness or lethargy, more severe headache and vomiting, cranial nerve dysfunction, focal neurological dysfunction, and mild abnormalities in limbs, sensation and movement. Grade IV, the patient mostly shows coma, mild to moderate coma. Patients with more severe symptoms of meningeal irritation signs and neurological deficits may present with denervation. The most severe grade is grade 5, where the patient is in a critical state, in a deep coma, unresponsive to all kinds of stimuli, and the patient will develop denervation and brainstem failure, and the prognosis is mostly poor. The Hunt-Hess classification is supplemented by clinical considerations of whether the patient has a combination of systemic diseases. If the patient is combined with hypertension, diabetes, multiple sclerosis, chronic lung disease, or extensive cerebral vasospasm on cerebral angiography, the Hunt-Hess classification will be increased by one level from the original one.