Three-dimensional spiral-shaping method of microcatheter for paraclinoid aneurysms: assessment using silicone models

Selecting an appropriate microcatheter tip shape for paraclinoid aneurysms is difficult. Therefore, we devised an original simple and uniform three-dimensional (3D) spiral-shaping method of microcatheter and validated the characteristics and usefulness of this method for coil embolization of paraclinoid aneurysms using patient-specific silicone models. These silicone models were produced based on clinical data from four patients with four paraclinoid aneurysms that underwent endovascular treatment using the 3D spiral-shaping method. These models were classified into four types: superior, medial, inferior, and lateral corresponding to the aneurysm protrusion and locations (C3 or C2 segments by Fisher's classification). Employing a pulsatile pump setup, two operators assessed the following items: navigation methods (pull and wire guiding), catheterization times, microcatheter tip position in the aneurysm, and the feasibility of inserting a framing coil by simple technique compared with three other shapes (straight, 90, pigtail). Three-dimensional spiral-shaped microcatheter could be placed in the medial and inferior type models of C3 segments and superior type model of C2 segment by the pullback method. Catheterization times using a 3D spiral-shaped catheter were significantly shorter than other shaped ones in the superior type models. No significant difference was found in another silicone model. Three-dimensional spiral- and pigtail-shaped catheters tended to position the tip at the center of the aneurysm. In conclusion, 3D spiralshaped microcatheter was especially effective for the superior projected aneurysm at the C2 segment. The 3D spiral-shaping method can provide easy and secure navigation of the microcatheter into the paraclinoid aneurysms, ensuring optimal positioning for coil insertion.