Neural supply of the male urethral sphincter: comprehensive anatomical review and implications for continence recovery after radical prostatectomy

Abstract

Purpose: To review the anatomical facts of urethral sphincter (US) innervation discovered over the last three decades and to determine the implications for continence recovery after radical prostatectomy (RP).

Methods: Using the PubMed^® database, we searched for peer-reviewed articles in English between January 1985 and September 2015, with the following terms: 'urethral sphincter,' 'urethral rhabdosphincter,' 'urinary continence and nerve supply' and 'neuroanatomy and nerve sparing.' The anatomical methodology, number of bodies examined, data, figures, relevant facts and text were analyzed.

Results: Seventeen articles on 254 anatomical subjects were reviewed. Coexisting pathways were described in every article. Dissection, histology, simulation or electron microscopy evidence supported arguments for somatic and autonomic pathways. From the most to the least substantiated, somatic sphincteric fibers were described extra- or intrapelvic as: direct from the distal pudendal nerve (PuN), recurrent from the dorsal nerve of the penis, from the proximal PuN with an intrapelvic course, extrapudendal somatic fibers dispersed among autonomic pelvic fibers. From the pelvic plexus, or from the neurovascular bundles, autonomic fibers to the US have been described in 13 of the reviewed articles, with at least each of the available anatomical methods.

Conclusion: Because continence depends on a number of factors, it is challenging to delineate the specific impact of periprostatic nerve sparing on continence, but the anatomical data suggest that RP surgeons should steer toward the preservation and protection of these nerves whenever possible.

Keywords: Innervation; Nerve sparing; Prostate; Urinary continence.