Eighth Cervical Nerve Root Block During Interscalene Brachial Plexus Block Decreases Pain Caused by Posterior Portal Placement but Increases Horner Syndrome in Patients Undergoing Arthroscopic Shoulder Surgery: A Randomized Controlled Trial

Abstract

Purpose: To compare the intensity of pain on posterior portal placement between a C5-C7 root block (conventional interscalene brachial plexus block [ISBPB]) and a C5-C8 root block in patients undergoing arthroscopic shoulder surgery. Methods: In this prospective, single-blinded, parallel-group randomized controlled trial, patients were randomized to receive either a C5-C7 root block (C5-C7 group, n = 37) or a C5-C8 root block (C5-C8 group, n = 36) with 25 mL of 0.75% ropivacaine. The primary outcome was the pain intensity on posterior portal placement, which was graded as 0 (no pain), 1 (mild pain), or 2 (severe pain). The secondary outcomes were the bilateral pupil diameters measured 30 minutes after ISBPB placement; the incidence of Horner syndrome, defined as a difference in pupil diameter (ipsilateral – contralateral) of less than –0.5 mm; the onset of postoperative pain; and the postoperative numerical rating pain score, where 0 and 10 represent no pain and the worst pain imaginable, respectively. Results: Fewer patients reported mild or severe pain on posterior portal placement in the C5-C8 group than in the C5-C7 group (9 of 36 [25.0%] vs 24 of 37 [64.9%], P = .003). Less pain on posterior portal placement was reported in the C5-C8 group than in the C5-C7 group (median [interquartile range], 0 [0-0.75] vs 1 [0-1]; median difference [95% confidence interval], 1 [0-1]; P = .001). The incidence of Horner syndrome was higher in the C5-C8 group than in the C5-C7 group (33 of 36 [91.7%] vs 22 of 37 [59.5%], P = .001). No significant differences in postoperative numerical rating pain scores and onset of postoperative pain were found between the 2 groups. Conclusions: A C5-C8 root block during an ISBPB reduces the pain intensity on posterior portal placement. However, it increases the incidence of Horner syndrome with no improvement in postoperative pain compared with the conventional ISBPB (C5-C7 root block). Level of Evidence: Level I, randomized controlled trial.