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 spiral-shaped 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.