[Abstract] Objective To investigate the method and effect of embolization with electrolytic detachable spring coil (GDC) in the treatment of intracranial aneurysm. Methods From May 2000 to October 2004, 15 cases of intracranial aneurysm were treated by embolization, including 5 male cases and 10 female cases, aged 20-68 years. There were 5 cases of proximal internal carotid artery aneurysm, 4 cases of distal internal carotid artery aneurysm, 4 cases of anterior communicating branch aneurysm, and 2 cases of apical basilar artery aneurysm. The aneurysm diameters ranged from a minimum of 5 mm to a maximum of 31 mm. All patients were embolized with GDC material. Results: 9 cases were embolized at 100%, 4 cases were embolized at 90% to 99%, and 2 cases were embolized at 70% to 90%. The postoperative clinical follow-up ranged from 1 to 12 months, and there was no rebleeding in any case. Conclusion Endovascular embolization for aneurysm is a safe, minimally invasive and effective treatment method, and the use of GDC embolization material is easy to operate and has few surgical complications. Keywords: aneurysm; embolization; detachable spring coil From May 2000 to October 2004, a total of 15 patients with intracranial aneurysm were treated by embolization with the electrolytic detachable spring coil (GDC) produced by Boston, which is reported as follows. 1. Data and methods 1.1 General data 15 patients with intracranial aneurysm had 16 aneurysms, including 5 males and 10 females; age ranged from 20 to 68 years old, with an average of 51 years old. There were 11 cases with subarachnoid hemorrhage onset and 4 cases with ptosis and occasional headache onset. Preoperative Hunt-Hess classification: grade I 3 cases, grade II 8 cases, grade III 4 cases. 1.2 Imaging data The whole group underwent cranial CT examination, 11 cases showed subarachnoid hemorrhage, 4 cases had no abnormal findings. 7 cases had cranial MRI examination with no abnormal findings. 5 cases had cranial MRA examination, 3 cases found aneurysm. There were 5 aneurysms in the proximal internal carotid artery, 4 aneurysms in the distal internal carotid artery, 4 aneurysms in the anterior communicating branch, and 2 aneurysms in the apical basilar artery. The minimum aneurysm diameter was 5 mm and the maximum was 31 mm. 1.3 Methods All patients underwent embolization under local anesthesia + intravenous assisted anesthesia. The right (or left) femoral artery was punctured with the Seldinger technique, and whole-brain angiography was performed first to understand the size, morphology, and location of the aneurysm, and to measure the diameter of the aneurysm neck and body. A 6F Envoy (Cordis) or Fas-Guide catheter (Boston), Track-18, Track-10 (Boston), Prowler-14, Prowler-10 (Cordis), and other double-labeled microcatheters and matching microguidewires were used as the guiding catheters. The shaped microcatheter at the head end was inserted into the aneurysm cavity and fixed at 1/3 of the distance from the aneurysm neck with the cooperation of the microguide. 1.4 Results At the end of embolization treatment, cerebral angiography was reviewed in 15 patients, and there were 9 cases of 100% embolization, 4 cases of 90%-99% embolization, and 2 cases of 70%-90% embolization. The whole group of patients were followed up clinically from 6 to 24 months after the operation, none of them had rebleeding, 13 cases recovered well, 1 case was left with actinic nerve palsy, and 1 case died. GDC embolization for intracranial aneurysm was first reported by Guglielmi et al. in 1991. the distal end of GDC is a platinum spring coil, which is connected with stainless steel guidewire and can be sent directly into the aneurysm. The GDC spring coil is extremely soft and has good compliance in the aneurysm, and can be adjusted again if the placement is not satisfactory, so that the aneurysm-carrying artery is not easily Occlusion is not likely to occur. The indications for endovascular embolization of cerebral aneurysms and embolization materials are closely related. In the 1980s, detachable balloons were mostly used for embolization of aneurysms that could not be surgically clamped, but it was difficult to adapt the balloons to the irregular shape of the aneurysm, which might burst the aneurysm and cause rupture. Thereafter, the free spring ring was used for aneurysm embolization, but its reliability was poor, and once the microcatheter was pushed out, it could not be retracted, and accidental embolization easily occurred. In recent years, the application of the new type of detachable spring ring has led to the great development of aneurysm embolization treatment, and the indications for embolization have been expanded and the efficacy has been significantly improved, and after the birth of GDC, it is considered the best material for embolization of aneurysm due to its superior performance. It has been reported abroad that 90% of intracranial aneurysms can be treated by embolization. The technology was introduced in China in 1998, and now endovascular treatment of intracranial aneurysms is becoming more and more common. Generally speaking, as long as the patient’s condition allows, GDC is in principle applicable to all cystic aneurysms where cannulation can be in place. Especially for aneurysms in the early stage of rupture, where surgery is difficult due to the severity of the disease, GDC embolization shows its unique advantages. There are two key steps in GDC embolization of intracranial aneurysms, the first is the precise placement of the microcatheter and its ability to be fixed in the aneurysm lumen, and the second is the selection of the appropriate type and size of the microspring coil. For the first step, the following three aspects need to be accomplished: (1) since the microcatheter is soft and must rely on the effective support of the guiding catheter, the guiding catheter should be inserted to the skull base in order to prevent excessive twisting of the microcatheter in the vessel; (2) the head end of the microcatheter should be shaped according to the angle between the aneurysm and the aneurysm-carrying artery and the distance from the center of the aneurysm lumen to the lateral wall of the aneurysm-carrying artery; (3) with the cooperation of the microguide wire The end of the microcatheter is kept at 1/3 to 1/2 of the aneurysm neck, and the smaller aneurysm can be placed at the neck of the aneurysm, so that the resistance is low and the spring coil can be wound. In order to make the embolization process go smoothly, it is crucial to choose the right microcoil. There are various microcoils available for the GDC embolization system, and there are two commonly used models, GDC-10 and GDC-18, each of which is divided into three specifications, namely, single-diameter type, double-diameter type (2-D) and three-dimensional type (3-D), among which the single-diameter type and double-diameter type are further divided into standard type and soft type. The following embolization techniques are currently used: (1) basket technique, in which one or more three-dimensional microsprings are fed into the aneurysm lumen first, and the spatial extension of the three-dimensional microsprings after release is utilized to form an aneurysm lumen. This technique is simple and easy to perform, but the disadvantage of this technique is that sometimes the spring coils still protrude outward after embolization. (2) Balloon-assisted reconstruction technique, in order to prevent the microcoil from protruding into the aneurysm-carrying artery, the microcatheter is inserted into the aneurysm lumen and then a non-detachable balloon catheter is inserted through the guiding catheter to the aneurysm opening, which fills the balloon and blocks the aneurysm opening, and then the aneurysm is occluded by the first method, which is better formed, but the disadvantage is that the blood flow needs to be blocked. (3) Stent-assisted reconstruction technique, in which an arterial stent is released to cover the opening of the aneurysm, and then a microcatheter is inserted through the mesh of the arterial stent to the aneurysm lumen and a microspring coil is fed to occlude the aneurysm. This technique solves the first two disadvantages, but the current dedicated stent does not have enough support. In our group, two cases of wide carotid aneurysm were embolized by the first method, and the result was satisfactory embolization without protrusion of the microspring coil into the aneurysm-carrying artery. Prevention and management of embolization complications: (1) Intraoperative aneurysm rupture: Mostly caused by improper operation of microcatheter and microguide wire or puncture of aneurysm wall during GDC placement, which can lead to fatal consequences if not treated in time. Once it occurs, heparin should be neutralized and blood pressure reduced immediately. If the tip of the microcatheter is in place, continue to fill the aneurysm with GDC until it is filled. In one case of this group, aneurysm rupture occurred intraoperatively. After the above treatment, the condition was rapidly controlled and a small amount of intracranial hemorrhage was confirmed by cranial CT scan, and postoperative treatment such as lumbar puncture and vasodilator was given, and the patient was discharged within a short time without any neurological dysfunction. (2) Intraoperative vasospasm: subarachnoid hemorrhage and endovascular operations can induce vasospasm. Preoperative use of nimotop, good intraoperative analgesic anesthesia, application of high-resolution fluoroscopy and tracer techniques operated gently as well as intraoperative use of poppies can effectively prevent and release the spasm. (3) Displacement of GDC occurs: Before each release of GDC, the position of the microcatheter tip and the position of GDC need to be confirmed by guide tube imaging to ensure that both are located in the aneurysm. In one of our cases, when the last GDC was released, the end of the GDC protruded into the aneurysm-carrying artery, and the displaced GDC was removed and repositioned with a Lasso catheter without any adverse effects. (4) Aneurysm recanalization: Most of them are caused by incomplete embolization, mainly seen in huge or wide carotid aneurysms. Therefore, dense filling is emphasized during embolization, and long-term follow-up should be performed, and those with aneurysm recanalization can be embolized again to achieve cure. Evaluation of embolization effect: The embolization effect depends on the degree of embolization, and the current evaluation of the degree of embolization is done by measuring the proportion of unfilled area in the aneurysm lumen under cerebral angiography, which is usually divided into the following cases: (1) 100% embolization (complete occlusion of the aneurysm lumen or complete occlusion of the aneurysm-carrying artery); (2) 90% to 99% embolization (a small amount of residual aneurysm neck or a small amount of filling in the aneurysm body); (3) 70% to 90% embolization (3) 70% to 90% embolization (large residual aneurysm neck or visible filling between the spring coils); (4) 50% to 70% embolization (more than 1/2 of the aneurysm lumen is filled by the spring coils, however, filling is retained at the base of the aneurysm).