Suprascapular vs. Interscalene Nerve Block 

Shoulder arthroscopic surgery is a common operation. Unfortunately, it is associated with a 45% rate of severe perioperative and postoperative pain [1]. Not only does pain contribute to patient dissatisfaction, but it can also impair recovery and rehabilitation and lead to pronounced opioid use [1]. As such, anesthesia providers commonly pair general anesthesia with regional nerve blocks when performing the procedure [1]. Interscalene nerve block (ISB) is the gold standard of regional nerve blocks, with success rates ranging from 87% to 100% during shoulder arthroscopic surgery [1, 2]. ISB covers the lateral two-thirds of the proximal humerus, shoulder, and clavicle regions [2]. It can be administered during surgery or following the operation as postoperative pain relief [1]. Unfortunately, despite its efficacy and versatility, ISB carries high risks such as unilateral diaphragmatic paralysis, nerve damage, and phrenic nerve paresis; Consequently, researchers have sought out alternatives to ISB, such as suprascapular nerve block [3]. 

First described in 1941, suprascapular nerve block (SSNB) has recently reemerged as a potential replacement for ISB [3]. SSNB is easily reproducible and relatively simple to administer [1]. Moreover, SSNB is performed further away from the neck than ISB, which diminishes its associated risk of complications [4].  

Given these purported benefits, recent studies have tested the differences between ISB and SSNB in terms of pain relief, satisfaction, and opioid usage. In 2017, Hussain and colleagues examined the data from 16 studies, which involved 1,152 shoulder surgery patients, to compare the two regional nerve blocks [3]. Excepting ISB’s improved pain control during patients’ recovery room stays, the researchers found no clinically meaningful analgesic differences between ISB and SSNB [3]. And, given the reduced incidence of side effects associated with SSNB, they concluded that, for shoulder surgery patients, suprascapular nerve block is a feasible alternative to interscalene nerve block [3]. 

In 2021, Sun et al. reported similar results when they analyzed the data from 1,255 patients undergoing shoulder arthroscopic surgery across 17 randomized controlled trials [1]. SSNB had comparable pain scores and lower rates of complications, including dyspnea, Horner syndrome, and hoarseness [1]. Meanwhile, both methods resulted in similar rates of vomiting, local tenderness, oral morphine use 24 hours after surgery, and patient satisfaction [1]. 

Despite these promising results, multiple other studies have concluded that SSNB is inferior to ISB, prompting some researchers to investigate ways to amend SSNB to make it more effective [5, 6]. One proposal is the addition of an axillary nerve block (ANB) to SSNB. So far, research indicates that SSNB paired with ANB may be an acceptable analgesic alternative to ISB [5]. It appears to produce statistically but not clinically different pain scores, as well as reduced incidences of nausea, vomiting, and dyspnea [4]. However, SSNB coupled with ANB results in longer operations because anesthesia providers must perform two blocks as opposed to one, so it may not be suitable for certain patients [5]. 

In conclusion, interscalene block and suprascapular block provide comparable pain relief and result in similar patient satisfaction rates. When treating shoulder surgery patients, anesthesia providers should weigh the possibility of complications against the patient’s particular comorbidities to decide whether to choose ISB or SSNB. 

References 

[1] C. Sun et al., “Suprascapular nerve block is a clinically attractive alternative to interscalene nerve block during arthroscopic shoulder surgery: a meta-analysis of randomized controlled trials,” Journal of Orthopaedic Surgery and Research, vol. 16, no. 376, p. 1-13, June 2021. [Online]. Available: https://doi.org/10.1186/s13018-021-02515-1. 

[2] J. Zisquit and N. Nedeff, “Interscalene Block,” StatPearls, Updated September 20, 2021. [Online]. Available: https://www.ncbi.nlm.nih.gov/books/NBK519491/. 

[3] N. Hussain et al., “Suprascapular and Interscalene Nerve Block for Shoulder Surgery: A Systematic Review and Meta-analysis,” Anesthesiology, vol. 127, no. 6, p. 9998-1013, December 2017. [Online]. Available: https://doi.org/10.1097/ALN.0000000000001894. 

[4] N. Cho et al., “Analgesic benefits and clinical role of the posterior suprascapular nerve block in shoulder surgery: a systematic review, meta-analysis and trial sequential analysis,” Anaesthesia, vol. 75, no. 3, p. 386-394, October 2019. [Online]. Available: https://doi.org/10.1111/anae.14858. 

[5] S. Dhir et al., “A Comparison of Combined Suprascapular and Axillary Nerve Blocks to Interscalene Nerve Block for Analgesia in Arthroscopic Shoulder Surgery: An Equivalence Study,” Regional Anesthesia & Pain Medicine, vol. 41, no. 5, p. 564-571, September-October 2016. [Online]. Available: https://doi.org/10.1097/AAP.0000000000000436. 

[6] J. Zhao et al., “Efficacy and safety of suprascapular nerve block combined with axillary nerve block for arthroscopic shoulder surgery: A systematic review and meta-analysis of randomized controlled trials,” International Journal of Surgery, vol. 95, p. 1-7, October 2021. [Online]. Available: https://doi.org/10.1016/j.ijsu.2021.106111.