Anatomic study of periprostatic nerve distribution: immunohistochemical differentiation of parasympathetic and sympathetic nerve fibres

Abstract

Background: Many authors advocate a high anterior incision during nerve-sparing radical prostatectomy (RP) to improve potency results. Despite a growing number of studies describing autonomic nerves in the ventrolateral position of the prostate, little is known about their quality and their role in erectile function.

Objective: The intention of this study was a detailed characterisation of the topographic distribution of periprostatic nerves, including immunohistochemical differentiation of proerectile parasympathetic from sympathetic nerves.

Design, setting, and participants: A total of 228 whole-mount sections of 38 prostates (base, middle, apex) from patients following non-nerve-sparing laparoscopic RP were analysed. Immunohistochemical analysis was performed using antibodies against tyrosine hydroxylase for sympathetic and vesicular acetylcholine transporter for parasympathetic nerve fibre staining.

Outcome measurements and statistical analysis: Quantification of periprostatic parasympathetic and sympathetic nerves was performed after defining prostatic regions via a digital grid. Differences among three independent variables were tested with the nonparametric Kruskal-Wallis test.

Results and limitations: The total number of parasympathetic nerves did not decrease from the base to the apex. They were dispersed at the base and mainly located dorsolaterally at the apex, with 14.6% above the horizontal line at the base and only 1.5% at the apex. In contrast, the total number of sympathetic nerves decreased significantly from base to apex, with a constant proportion of ventrolateral nerves between 9% (base) and 6.2% (apex). This anatomic study is limited by the investigation of postprostatectomy specimens and the lack of functional results.

Conclusions: Despite the presence of ventrolateral periprostatic nerves, only a minority of these nerves seems to have a parasympathetic proerectile quality. The arguments in favour of a high anterior incision during nerve-sparing prostatectomy might not only include preserved nerves but also other factors, such as reduced traction or improved anatomic support of the neural structures.