Purpose: Neurostimulation of the pudendal nerve (PN) is considered for patients who have failed sacral neuromodulation. Previous techniques for PN localization are described to be uncomplicated and promise to achieve accuracy in electrode placement. However, in clinical use, they appear challenging. We developed a puncture technique using fixed anatomical landmarks for a fast and reproducible localization of the PN.
Methods: Full-body cadavers and dissected anatomical preparations were studied for the course of the PN. Fluoroscopically controlled fixed anatomical landmarks locating the pudendal trunk were defined. Lead placement following established techniques was performed, and the topographic relationship to the PN was documented by dissection. In a pilot series of 20 patients with chronic pelvic pain, pudendal neuromodulation (PNM) was performed uni- and bilateral using the different approaches. Technical and clinical outcomes of the various techniques were compared.
Results: Fixed anatomical landmarks such as ischial spine, ischial tuberosity, acetabulum and anal rim resulted in a right-angled triangle with a new start and target point for puncture. Initials of the landmarks add up to the teaching acronym STAR. STAR technique including a puncture angle of 60° and a gluteal lead exit places 3-4 electrode poles at the nerve. In clinical trial, mean operation time for bilateral PNM in STAR was 85 min with mean puncture attempts of 3.5 to reach the nerve. Pain decreased statistically significant only in bilateral PNM.
Conclusions: The STAR approach appears to achieve technical standardisation and optimized reproducibility in pudendal lead placement resulting into an increased feasibility of PNM.