Minville, Vincent

Abstract Objectives The primary aim of our study was to evaluate and compare the accuracy of ultrasound (US)-guided distal suprascapular nerve (dSSN) and proximal SSN (pSSN) blocks. Secondary aims were to compare the phrenic nerve involvement between groups and to describe the anatomical features of the sensory branches of the dSSN. Methods pSSN and dSSN blocks were performed in 14 cadavers (28 shoulders). Ten mL of 0.2% ropivacaine colored with methylene blue was injected under US guidance. Accuracy was determined using SSN staining and the distance between predefined anatomical landmarks and the targeted SSN. The phrenic nerve (PN) was judged to be colored or not. The distribution of the sensory branches that originate from the 14 dSSNs is described. Quantitative data are expressed as median (range). Results The pSSN was dyed more frequently than the dSSN (13 vs 11, P = 0.59). The targeted SSN was close to the suprascapular notch (1.3 [0–5.2] cm) and the origin of the SSN (1.4 [0.2–4.5] cm) for dSSN and pSSN blocks, respectively (P = 0.62). For dSSN blocks, the most frequent injection site was the supraspinous fossa. Three PNs were marked in pSSN blocks, compared with none in dSSN blocks (P = 0.22). Three sensory branches were identified for all 14 dSSNs: the medial subacromial branch, the lateral subacromial branch, and the posterior glenohumeral branch. Conclusions US-guided pSSN and dSSN blocks can be realized with accuracy. A distal approach to the SSN could be an alternative to interscalene brachial plexus block for the management of postoperative pain after shoulder surgery in high–respiratory risk patients.

Difficulty in identifying the susprascapular nerve (SSN) limits the success of US‐guided regional anesthetic injections. A proximal SSN block could be an effective and reliable approach. The primary objective was to validate the feasibility of the US‐guided proximal SSN block. The secondary objective was to quantify the spread of the colored local anesthetic to the phrenic nerve (PN). Fourteen brachial plexuses from seven cadavers were included. Characterization of the proximal SSN was performed using US to determine the diameter and depth of the origin of the SSN (orSSN). Ten mL of methylene blue‐infused ropivacaine 0.2% were then injected to the proximal portion of the SSN. After dissection, the distances between the tip of the needle and the orSSN and the PN were anatomically determined. The PN was also judged to be colored or not by the methylene blue. The mean diameter and depth of the orSSN were 0.2 cm (range, 0.1‐0.3 cm) and 1.5 cm (range, 0.6‐2 cm) respectively. The orSSN was successfully targeted in 14 of 14 specimens with US; the tip of the needle was a mean of 1.6 cm (range, 0.2‐2.5 cm) and 5.1 cm (range, 4‐6.5 cm) from the orSSN and PN respectively. The orSSN and PN were marked in 14 and 3 cases respectively. US‐guided proximal SSN block is effective and reliable. The origin of the SSN is an easily identifiable landmark. This regional anesthesia could also reduce the risk of phrenic nerve palsy following interscalene brachial plexus block. Clin. Anat. 31:824–829, 2018. © 2018 Wiley Periodicals, Inc.