Classification of disease: Hunt and Hess grading scale Grade 0 Unruptured aneurysm Grade I Asymptomatic or mild headache Zhang Xiaobo, Department of Interventional Therapy, Peking Union Medical College Hospital Grade II Moderate to severe headache. Meningeal irritation sign. Cranial nerve palsy Grade Ⅲ Drowsiness, cloudy consciousness, mild focal neurological signs Grade Ⅳ Coma, moderate or severe hemiparesis, with early denervation or autonomic dysfunction Grade Ⅴ Deep coma, denervation. If the patient’s general condition can tolerate anesthesia and the technique can achieve the therapeutic purpose, interventional therapy can be performed. If the patient’s general condition can tolerate anesthesia and the technique can achieve the treatment purpose, interventional therapy can be performed. Contraindications ①The patient’s general condition cannot tolerate anesthesia. ②The current interventional technology cannot achieve the treatment purpose. ③Patients and/or family members refuse interventional treatment. Preoperative preparation 1. Routine blood and urine tests, bleeding and clotting times, liver and kidney function, electrocardiogram and other routine tests. 2.CT examination:The diagnosis of SAH can exclude other concomitant intracranial disorders. Intensive high-resolution thin-layer scan can detect aneurysms >5mm in diameter, and can find out whether there is calcification in the aneurysm wall or whether there is thrombosis in the aneurysm. Spiral CT 3D reconstruction can initially screen aneurysms. 3.MRI/MRA (as appropriate): It can roughly show the location of aneurysm, show whether there is thrombosis within the aneurysm, and clearly show the relationship between the aneurysm and the surrounding brain tissue. 4.Cerebral angiography: ①Timing of angiography, patients with SAH who are highly suspected of intracranial aneurysm should be angiographed as soon as possible, and patients with Hunt-Hess grade IV-V should be angiographed as appropriate. ②The principle of imaging, when intracranial aneurysm is highly suspected, whole brain angiography should be performed, including bilateral internal carotid arteries and bilateral vertebral arteries. The vertebral arteries should show the bilateral posterior inferior cerebellar arteries. If necessary, external carotid artery and spinal angiography should be added. In case of aneurysm of one internal carotid artery, a cross-circulation test should be performed at the same time, i.e., compression of the affected internal carotid artery and contralateral internal carotid artery and vertebral artery should be performed to observe the compensatory capacity of Willis loop. If necessary, multiple angles of projection or three-dimensional reconstruction should be performed, and those with negative SAH angiograms should be reexamined after 2 weeks. Reasons for false negative cerebral angiogram: spasm of the aneurysm-carrying artery, too small aneurysm, thrombus in the aneurysm cavity preventing the entry of the contrast agent, poor equipment conditions, no multi-angle angiographic observation, and failure to identify the aneurysm by reading the film. Operation method 1.Aneurysm intracapsular embolization: ①Embolization materials, 5-7F soft tip guiding catheter, guidewire guiding microcatheter (10, 14, 18 series), microguiding wire (10, 14, 18 series) matched with microcatheter, controlled release spring ring and release system, liquid embolization material and its embolization system. ②Embolization points, general anesthesia and general heparinization as much as possible (except within 4h after SAH). Select 1-2 best working angles according to the imaging results so that both the aneurysm neck and the aneurysm body are clearly shown. Microcatheter shaping is performed according to the location and morphology of the aneurysm. The microcatheter should be operated slowly and smoothly, without jumping forward. The tip of the microcatheter should not be placed against the aneurysm wall. The selection of the spring coil should be based on the measurement of the aneurysm. The diameter of the first coil should be larger than the aneurysm neck, equal to or slightly larger than the minimum diameter of the aneurysm, and as long as possible so that it can be coiled into a basket shape against the aneurysm wall within the aneurysm. For small aneurysms with recent bleeding, a soft spring coil should be selected whenever possible. The proper placement of the spring coil should be confirmed by imaging to ensure that there is no normal vascular occlusion before uncapping. The spring coil should be filled as densely as possible. 2, balloon reshaping protection technology: ① embolization materials, in addition to the above materials, need to prepare the corresponding size of the protection balloon. ②Embolization points, applicable to wide carotid aneurysm. For liquid embolic agent embolization, the protective balloon must be used. The time of occlusion of the aneurysm-carrying artery by the balloon should be shortened as much as possible, generally not more than 5 min each time, and the spring ring embolization should be as dense as possible. 3.Stent-assisted techniques:①Embolytic materials, in addition to the above materials, need to prepare the corresponding size of self-expanding stent or balloon-expanding stent. Use protective balloon if necessary. ②Embolization points, applicable to cases of wide carotid aneurysm, shuttle aneurysm, sandwich aneurysm and severe stenosis of the aneurysm-carrying artery near the aneurysm. Anti-platelet aggregation drugs should be given sufficiently before and after surgery to avoid entanglement of the spring ring with the stent, and displacement and collapse of the stent should be avoided. 4. Aneurysm-carrying artery occlusion technique: ①indications and conditions, internal carotid artery and posterior circulation shuttle, wide neck, huge aneurysm; those who cannot or are not suitable for intra-aneurysm embolization, such as pseudo or entrapment aneurysm; adequate compensation of collateral circulation and negative balloon occlusion test (BOT). ② Clinical signs of negative balloon occlusion test, no neurological disorder, negative reinforcement test (20-30 mm Hg, 20-30 min). ③The imaging sign of adequate compensation of the collateral circulation is good capillary filling on the affected side when the healthy cerebral arteriogram is performed after balloon occlusion; the bilateral venous phase appears at the same time, and the difference between the filling time on the affected side and the filling time on the healthy side