Sacral nerve stimulation in sacral agenesis using 3D printing and intraoperative navigation: report of two cases and narrative review

Caudal Regression Syndrome (CRS) is a rare malformation characterized by lumbosacral deformities and gastrointestinal/genitourinary and/or lower limb abnormalities. Sacral neuromodulation (SNM) is an effective therapy for refractory gastrointestinal/genitourinary symptoms but lead implantation near the S3 roots is challenging in patients with sacral deformities due to the absence of standard fluoroscopic landmarks. We describe a method for percutaneous lead implantation in patients with sacral deformities, using preoperative 3D-printed anatomical replicas combined with intraoperative navigation. Our first two cases are reported. Two CRS patients with sacral agenesis and refractory neurogenic lower urinary tract dysfunction underwent this procedure. Preoperative imaging was processed to create a 3D-printed sacrum, and the sacral roots were replicated using silicone threads. These models enabled anatomical analysis, target identification, and planning of the foramen entry point and introducer angle. The plan was integrated into the NN system, and awake surgery was performed with neurophysiological monitoring. Intraoperatively, navigation allowed real-time visualization of the introducer's position and placement of the electrode at the desired location and depth. Correct positioning was confirmed by stimulation with a typical S3 response (hallux flexion and bellows reflex) and fluoroscopy. Both patients proceeded to permanent generator implantation with clinical improvement. The presence of a 3D replica improves the spatial understanding of sacral anatomy. Together with navigation, it can be used to overcome the technical challenge of placing SNM electrodes in patients with bony deformities. • 3D printing and intraoperative navigation were used to optimize sacral neuromodulation in patients with sacral agenesis. • Patient-specific 3D anatomical replicas improved preoperative planning and trajectory planning and visualization. • Navigation provided real-time guidance, ensuring precise lead implantation despite anatomical challenges. • The navigation reference frame was secured to the surgical table, avoiding additional skin incisions. • This approach allowed percutaneous lead implantation in cases previously considered unsuitable for sacral neuromodulation.