Although aneurysm neck clamping remains as the gold standard for the treatment of intracranial aneurysms, the procedure may aggravate the patient’s condition or even lead to death due to its high invasiveness and risk, especially in posterior circulation aneurysms and in patients with severe disease. The idea of applying vascular pathways as a way to reach and treat intracranial vascular lesions has largely stimulated the development of various delivery systems (e.g., microcatheters, etc.) and other devices in the trend of promoting minimally invasive treatment of disease. The tortuosity, stenosis and irregularities of the intracranial arteries, such as the siphon of the internal carotid artery, become obstacles to the superselection of intracranial catheters, making treatment more difficult. The intracranial arteries are surrounded by the brain parenchyma and supply the brain tissue, which can have fatal consequences in case of cerebrovascular injury or rupture. In the past years, some research pioneers have made great efforts to break through this “forbidden area”. In 1964, two American neurosurgeons, Luessenhop and Velasquez, first reported catheter overshoot of intracranial vessels. They delivered a silicone tube into the internal carotid artery through a glass tube attached to the external carotid artery and could further superselect the intracranial vessels. One type of flow-guided catheter, with a balloon-like expansion of the tip, was successfully used to temporarily close the neck of a large posterior communicating aneurysm. They predicted that “catheter superselection would be as valuable as embolization of intracranial arteries, especially in the treatment of aneurysms and arteriovenous malformations”. However, in those days, catheterization of cerebral arteries was considered very difficult and dangerous. A catheter introduced by the Israeli scientist Frei and colleagues in 1966, specifically for use in minimal trauma superselection, had a proximal portion made of polyethylene and a distal portion made of a soft silicone rubber. The distal portion has an outer diameter of 1.3 mm and a length of 7 cm. The head end of the silicone tube is encased in a 1 mm diameter micromagnet, and under the action of an external magnetic field, a continuous magnetic field pulls the head end of the catheter forward, while a changing magnetic field causes the head end to vibrate (oscillate). The effect is to reduce the friction between the tip of the catheter and the lumen of the vessel to allow the catheter to “swim” within the vessel. The authors also propose the concept of a guide catheter and the use of a “T” tube, which can be used to flush the guide catheter through a microcatheter or by injecting saline. Thirty years later, we are still using this system proposed by Frei. The concept of magnetic guidance became quite popular in the 1960s, and the flow-guided balloon microcatheter was slowly gaining acceptance in the 1970s and early 1980s. In 1967, Yodh et al. investigated the cephalic detachable catheter and proposed the value of catheters in the treatment of cerebrovascular disease: (1) blocking the blood supplying arteries of intracranial vascular malformations by detachable cephalic ends or injection of coagulable colloids; (2) embolization therapy of aneurysms; and (3) treatment of gliomas by intra-catheter injection of chemotherapeutic agents. These concepts were still widely used in the next 30 years. Afterwards, a number of authors continued to study and improve the external magnetic field-guided catheter and began to apply it clinically. in 1970, Montgomery first designed a balloon catheter for intravascular application, and in 1973 Cares et al. described the method of intra-aneurysmal balloon embolization therapy. in 1974 Hilal et al. reported the results of clinical application. Despite the success reported, this system has not been widely used because the external magnetic field equipment is cumbersome and the magnetic field may affect the X-ray image; a catheter with a balloon at the cephalic end may be more appropriate. However, the real milestone in the history of neurovascular guidance came in the mid-1980s when Erik Engelson first proposed the idea of guidewire guidance and attached a very short section of guidewire to the distal end of the polyethylene portion, which was softer than polyethylene but stiffer than silicone tubing, and this catheter was named Track and was used in clinical patients in 1986. This catheter was named Track and was used in clinical patients in 1986. This catheter was named Track and was used in clinical patients in 1986. The catheter can be super-selected on the micro-guide wire for various parts of the blood vessels. In 1970, Kessler and Wholey and in 1971, Prolo and Hanbery reported on the percutaneous application of non-detachable balloons to occlude the internal carotid artery for the treatment of aneurysms and internal carotid cavernous sinus fistulas, and in 1974, the Soviet scholar Serbinenko reported on the experience of using balloon catheters and detachable balloons for the endovascular treatment of intracranial aneurysms. Debrun, Merland and Berenstein treated aneurysms by balloon occlusion of the aneurysm-carrying artery, while Hieshima and Moret preferred intra-aneurysm balloon embolization for the treatment of The aneurysm was treated by balloon occlusion of the aneurysm-carrying artery, while Hieshima and Moret preferred intra-aneurysmal balloon embolization for aneurysms while maintaining patency of the aneurysm-carrying artery. Currently, occlusion of the aneurysm-carrying artery is still used in the treatment of giant and spindle-shaped aneurysms, while intra-vesicular balloon occlusion has been gradually replaced by spring-ring tamponade. In the report of Higa***a, the disability and mortality rates for balloon embolization of aneurysms not suitable for surgical treatment were 11% and 18%, respectively. The mortality rate can be as high as 22%, especially in the presence of vasospasm. It is because of this high residual mortality rate that intracapsular embolization for aneurysms is gradually changing from balloon to spring-ring embolization. The intracapsular balloon is usually filled with HEMA, a cementing agent to prevent premature balloon ejection; the HEMA-filled balloon is stiffer and easily transmits the energy of the systolic beats to the arterial wall. The spring coil inside the balloon absorbs some of the energy, partially relieving the transmitted blood pressure before the systolic beat wave hits the aneurysm wall. This effect may explain the difference in early bleeding rates between the two treatment modalities, with the application of spring-ring embolization to treat aneurysms resulting in significantly lower rebleeding rates than in patients with balloon embolization. 3. Microspring coil system Although spring coils have been used to occlude carotid arteries, the application of thrombogenic spring coils for intra-aneurysmal embolization of intracranial aneurysms was first reported by Hilal in 1989. Microspring coils have been widely used because of their ability to completely embolize aneurysms of different sizes and shapes by performing block filling within the aneurysm. The microsprings used to embolize the tumor supply artery were replaced by detachable coils, which were longer and could be mechanically or electrolytically released by the operator from the delivery guidewire, due to their short length and the difficulty of accurately placing them to occlude the aneurysm. In 1990, a more classical vascular approach, the application of controlled and electrolytic detachable platinum coils (Guglielmi detachable coil, GDC), offered a more minimally invasive and safe approach to the treatment of intracranial aneurysms. The coil is very flexible to avoid damaging the aneurysm wall, adapts well to the shape of the aneurysm so as not to cause excessive distortion of the fragile wall, and can be used to fill the aneurysm lumen as completely as possible. The spring coils can easily change shape to accommodate the systolic pulsation effect. Mechanically removable spring coils (MDS) and tungsten wires have also been used to embolize aneurysms with good results, although they are less safe and less controllable, but their lower price makes them more suitable for the Chinese situation. New types of spring coils are constantly improved, such as 3D-GDC and modified GDC (modified GDC), the latter refers to the application of various protein-modified spring coils to make it easier to promote thrombosis and endothelialization of the aneurysm neck in vivo in order to completely isolate the aneurysm from the blood circulation. The concept of stent system was first proposed by Charles Dotter in 1969, and Cragg et al. and Dotter et al. first reported the placement of intravascular forceps titanium stents in porcine arteries in 1983. In 1987, Rousseau et al. first reported the use of stents in humans. After that, endovascular stents gradually gained recognition in the treatment of peripheral vascular lesions and coronary artery lesions. However, the tortuosity and stenosis of cerebral vessels, especially the siphon segment of the vertebral and carotid arteries, make intracranial stent delivery a major challenge, and there are no intracranial-specific endovascular stents available. However, this did not stop the neurosurgeons, and they continued their efforts. 1994 Geremia et al. first tried to place intracranial stents in a porcine aneurysm model and filled the aneurysm through the mesh of the stent with satisfactory results. Since then, many other scholars, who conducted related studies, concluded that: intracranial endovascular stent placement is feasible, and the stent can cover the neck of the aneurysm, making embolization therapy with spring coils or liquid embolic agents safer and preventing compression or occlusion of the aneurysm-carrying artery. In addition, by altering the intra-aneurysmal hemodynamic pattern, intra-aneurysmal thrombosis can be promoted. In 1997, Higa***a successfully applied the Palmaz-Schatz PS 1540 stent across the neck of a basilar aneurysm and stabilized the spring coil in the lumen of the aneurysm while maintaining vessel patency. In 1998, Lanzino et al. first described the use of AVE coronary stents for paracranial aneurysms, and this group subsequently treated 10 intracranial aneurysms. However, the authors performed embolization after direct surgical exposure of the vertebral artery rather than through the femoral route. In China, Shanghai Changhai Hospital was the first to successfully apply this technique to treat intracranial shuttle vertebral artery aneurysms. Up to June 2002, 52 cases of intracranial wide carotid aneurysm have been treated with this technique and good results have been achieved. In addition, we were the first in the world to perform stenting of the bifurcation of the internal carotid artery for the treatment of wide carotid aneurysms and stenting of aneurysms combined with stenosis. At present, there are not many units that can carry out this technology in China. Certainly, the lack of intracranial-specific stents is still an important factor limiting the application of this technology in the treatment of cerebrovascular disease. While the endovascular treatment technology continues to develop, neurosurgeons and interventional neuroradiologists are also working hard, and they make various active attempts. The use of liquid embolic agents has provided great convenience for endovascular treatment, and those currently under investigation include fibrin acetate and ONYX, but clinical applications still require further reduction of toxicity, among others. Although some methods are still in the experimental research stage and have not yet been applied in clinical practice, it can be said that it is their bold innovation and unique conceptions that have led to the rapid development of neurointerventional radiology in recent years. However, we should also see: despite the rapid development of endovascular treatment of intracranial aneurysms in the last 20 years, for some cases, the aneurysm-carrying artery can only be occluded via the endovascular route. The majority of patients can be occluded by applying a GDC spring coil to the aneurysm itself, but embolization is not yet a complete substitute for clamping. However, it may be the best option for patients who cannot undergo surgery, and in some cases, a combination of embolization and clamping may be used. In some cases, embolization may be performed first to stabilize the patient, followed by clamping. Close collaboration between the neurosurgeon and the interventional neuroradiologist can help provide the best possible treatment for the patient.