Upper trunk block for shoulder analgesia with potential phrenic nerve sparing: a preliminary anatomical report

Abstract

Background and objectivesIpsilateral phrenic nerve palsy (PNP) is an undesirable side of conventional approaches to interscalene brachial plexus blocks. The purpose of this study was to demonstrate whether or not the phrenic nerve can be spared by dye when injected at the division of the upper trunk of the brachial plexus.MethodsUnder ultrasound guidance, 5 mL of radiolabeled dye was injected between the anterior and posterior division of the upper trunk in two fresh, cryopreserved cadavers. CT scan analysis, cadaveric dissection, and cryosectioning were performed to examine the spread of the injectate.ResultsWe found staining of the injectate over the entire upper trunk with its anterior and posterior divisions, the suprascapular nerve under the omohyoid muscle and the lateral pectoralis nerve, and the C5 and C6 roots. The middle trunk was partially stained. There was no evidence of dye staining of the lower trunk, anterior aspect of the anterior scalene muscle, or the phrenic nerve.ConclusionsOur study offers an anatomical basis for the possibility of providing shoulder analgesia and avoiding a PNP.

Ultrasound-Guided Upper Trunk Perineural Catheter for Shoulder Surgery: A Description of Catheter Technique

“…A stimulating catheter is then advanced such that the biceps twitch is preserved throughout (Figure 4 ). We almost always find that the needle at this juncture is in the middle of the upper trunk, most likely in between its anterior and posterior divisions, making this technique extremely reproducible [ 3 ]. The presence of rich connective tissue in the upper trunk, which was demonstrated by Aguirre et al in histological preparations, can be seen clearly by ultrasound [ 2 ].…”

“…Ultrasound-guided upper trunk block is considered a safer but equianalgesic alternative to interscalene block [ 4 ]. Cros Campoy et al injected 5 mL radiolabeled dye between the anterior and posterior divisions of the upper trunk of two fresh cadavers and found that it stained not only the entire upper trunk along with the suprascapular nerve but also the C5 and C6 roots [ 3 ]. The middle trunk was also found to be partially stained, with no evidence of dye staining the lower trunk, anterior aspect of the anterior scalene muscle, or the phrenic nerve [ 3 ].…”

“…Cros Campoy et al injected 5 mL radiolabeled dye between the anterior and posterior divisions of the upper trunk of two fresh cadavers and found that it stained not only the entire upper trunk along with the suprascapular nerve but also the C5 and C6 roots [ 3 ]. The middle trunk was also found to be partially stained, with no evidence of dye staining the lower trunk, anterior aspect of the anterior scalene muscle, or the phrenic nerve [ 3 ]. A brachial plexus sonoanatomy report determined that the upper, middle, and lower nerve trunks stay together in the interscalene region, and the spread of the neural elements at the two levels recorded were no different from one another, implying that a nerve block can be adequately performed at a range of levels within the interscalene groove and not just the classical position at the level of the C6 vertebra [ 9 ].…”

“…The single-injection technique for blockade of the upper trunk of the brachial plexus was first brought to light by Burkett-St Laurent et al in 2014 [ 1 ] followed by Aguirre et al in 2016 [ 2 ]. The upper trunk block has been successfully demonstrated in cadavers, and two randomized control trials have further established the advantage of blocking the upper trunk over the conventional interscalene block in preserving the phrenic nerve function [ 3 - 5 ]. However, the continuous perineural catheter technique has not yet been promulgated in the literature.…”

Diaphragm-sparing nerve blocks for shoulder surgery, revisited

“…Thus, the more distal injection site provided by upper trunk block could theoretically result in a lower incidence of HDP than ISB. In fact, in a recent anatomical study, Cros Compoy et al 36 reported that 5 mL of dye injected at the level of the upper trunk results in staining of the suprascapular nerve, lateral pectoral nerve as well as C5 and C6 roots but not of the phrenic nerve. To date, only one RCT has compared upper trunk blocks and ISBs for shoulder surgery.…”