the aneurysm. The treatment uses detachable coils made of platinum that are inserted into the aneurysm using the microcatheter. A variety of coils are available, including Guglielmi Detachable Coils (GDC) which are platinum, Matrix coils which are coated with a biopolymer, and hydrogel coated coils. Coils are also available in a variety of diameters, lengths, and cross sections. A coil is first inserted along the aneurysm wall to create a frame, with the core then being filled with more coils. A series of progressively smaller coils may also be used. Success is determined by injecting a contrast dye into parent artery and qualitatively determining if dye is flowing into the aneurysm space during fluoroscopy. If no flow is observed, the procedure is considered completed. In the case of wide-necked aneurysms a stent may be used. History Endovascular coiling was a developed through the synthesis of a number of innovations that took place between 1970 and 1990 in the field of electronics, neurosurgery, and interventional radiology. While the procedure itself has been and continues to be compared to surgical clipping, the development of the concept and procedure has resulted in it becoming the gold standard at many centers. Filling the intravascular compartment The first documented technique of using metal coils to induce thrombosis was accomplished by Mullan in 1974. Copper coils were inserted into a giant aneurysm through externally puncturing the aneurysm wall via craniotomy. Five patients died, with ten having satisfactory process. It did not gain popularity due to the specialized equipment required, in addition to the technique being unsuitable for many types of aneurysms. Later, in 1980, similar techniques were developed by Alksne and Smith using iron suspended in methyl methcrylate in a limited set of patients. There were no deaths in 22 consecutive cases with low morbidity. This technique also did not gain traction due to advances in clipping. Endovascular approaches As a means of avoiding invasive methods, early endovascular interventions involved the usage of detachable and nondetachable balloon catheters to occlude the aneurysm while preserving the parent artery. Despite the innovative approach, the aneurysms were often found to adapt to the shape of the balloon itself resulting in higher incidents of aneurysm rupture. This procedure was deemed "uncontrollable" due to its high morbidity and mortality rate, but it demonstrated that the endovascular approach was feasible for many aneurysms. Endovascular coils would later be used in 1989 by