Periprostatic innervation: New issues based on segmental analysis of 10 human cadaver pelvic blocs

The exact paths of periprostatic nerves have been under debate over the last decades. In the present study, the topographic distribution of nerves around the prostate and their relative distances from the prostatic capsule were analyzed in male cadaver visceral blocs.

The pelvic organs from ten fresh male cadavers were removed and serial sectioned en bloc for histological investigation. The macroslices was divided into four sectors. Each sector was centrally covered with a raster dividing each sector in three subsectors numbered clockwise. The prostatic capsule was identified, and distances of 2.5 and 5 mm from the prostate were demarked with lines. We quantified the number of nerve fibers present in each subsector of each slide and recorded their position relative to the prostatic capsule.

In general, the topographic analysis revealed that the majority of nerves were identified in sectors 4 through 9, corresponding to the posterolateral and posterior surfaces of the prostate gland. At the prostate base, the majority of nerves were found at the posterolateral and posterior surfaces of the gland. Within the mid-region of the prostate, the same topographic distribution pattern was observed, but the nerve fibers were closer to the prostatic capsule. At the apical region, the percentage of nerve fibers identified in the anterior region was higher, despite their major concetration in the posterior surface. The nerves identified at the apex were mainly located up to 2.5 mm from the prostate. This proximity to the prostate was specifically observed in the anterolateral and anterior sectors. In the craniocaudal sense, the percentage of nerves identified between 2.5 and 5 mm from the prostatic capsule remained constant.

A significant number of nerve fibers were present in the anterior and anterolateral positions, especially at the apex. The anterior nerves were closer to the prostate. This proximity suggests that the anterior nerves may participate in local physiology and that the cavernous nerves are probably formed by the posterior nerve fibers. It is likely that the safe distance of 2.5 mm from all surfaces of the prostate may be related to cavernous fiber preservation.