DPNB vs. Modified DPNB With Ventromedial Infiltration (DPNB According to Dalens' Technique)

Overview

Dorsal penile nerve block (DPNB) is a regional nerve block probably most often performed throughout the world. There are several different methods described in the literature. When compared to penile ring wall infiltration or caudal block, the Dorsal penile nerve block (DPNB) is more likely associated with the risk of failure of the block quality. The aim of this study is to compare the quality of the standard method of Dorsal penile nerve block (DPNB)(Dalens' technique) with that of a modified procedure (Dorsal penile nerve block (DPNB)with additional infiltration of the ventromedial penis at the transition between the penis and the scrotum.

Male circumcision is the most often performed operation in male children throughout the world. In the western world it is not accepted to perform this procedure without adequate analgesic support. Hence the dorsal penile nerve block (DPNB), first described in the 70ies of the 20th century, is one of the most frequently performed regional anesthetic procedures in both children and adults. There are several methods described in the literature, of which the one described by Dalens et al in 1989 nowadays is the most often quoted and most frequently performed method. The reported rate of insufficient analgesia by DPNB is higher than caudal block or penile ring wall infiltration. It is known from neuroanatomic studies, that the penis is innervated mostly, but not only by the dorsal penile nerve, a final branch of the pudendal nerve. A varying amount of the ventral penile skin, especially of the preputium and the frenulum, is innervated by fine end branches of the perineal nerve, which otherwise gives sensoric innervation to the scrotum and motor innervation to the bulbospongiosus muscle. An injection of local anesthetic underneath Buck's fascia is unable to reach the perineal nerve, which may be the explanation for these failures. In this study we compare two different techniques of performing the dorsal penile nerve block (DPNB): the technique according to Dalens, and a modification, where a small amount of the local anesthetic for the dorsal penile nerve block (DPNB) is withheld, and then injected subcutaneously at the ventral transition between the penis and the scrotum in the midline. The latter injection at the site of perineal innervation is a relic of the penile ring wall infiltration, which surely blocks all skin fibres of both the dorsal penile nerve and the perineal nerve. All patients included randomly receive either two injections at the dorsum penis according to Dalens' technique, or two injections at the dorsum penis according to Dalens' technique plus on subcutaneous injection in the ventral midline of the penis at the transition between the penis and the scrotum. The amount of local anesthetic (bupivacaine 0,75%, 0,2 ml/kg of body weight) and dosing of narcotics (Sevoflurane 2,2 Vol% end-expiratory gas in an oxygen-air mixture) is the same in both groups.