Proximal Approach of Ultrasound-guided Suprascapular Nerve Block: Comparison with Subacromial Steroid Injection

Variability in the distance between the suprascapular notch with the spine of the scapulae and the acromion

INTRODUCTION

The suprascapular notch lies in the superior border of the scapula and is a passageway for the suprascapular nerve that is sensory to the shoulder joint. Suprascapular nerve block involves injection of local anaesthetic into the suprascapular notch, either ultrasound guided or blind, using the spine of scapula and/or the medial border of the acromion as surface landmarks.

AIM

To investigate the anatomic variations that exist between the distance of the notch from the spine of scapula and acromion.

METHOD

Ninety-two dry scapulae were measured with a digital calliper for their length of the spine, distance between the midpoint of the spine and base of the suprascapular notch and distance between the medial border of the acromion and the base of the suprascapular notch. These measurements were compared for variations in the scapular bony landmarks, the spine and the acromion to determine the site for the injection.

RESULTS

Measurement reliability was assessed by intraclass correlation, Cronbach's alpha being 0.99, 0.97 and 0.91 for length of spine, distance from spine and distance from acromion respectively. The distance from the acromion had less variation in measurement (3.73 ± 0.42 cm) but a flatter distribution when compared to distance from the spine of the scapula (3.32 ± 0.39 cm).

CONCLUSION

Length of the spine of the scapula appeared not to influence either distance from the acromion or distance from the spine of scapula. There is potential for greater variability in placement of nerve blocks that use acromion as the bony reference. Key Points • Dry scapular measurement using electronic Vernier callipers is accurate (0.91-0.97). • There is potential for greater variability in placement of blind nerve blocks that use acromion as the bony reference to locate the suprascapular notch.

Ultrasound-guided musculoskeletal interventional procedures around the shoulder

Ultrasound is a fast, accessible, reliable, and radiation-free imaging modality routinely used to assess the soft tissues around the shoulder. It enables to identify a wide range of pathological conditions. Furthermore, most ultrasound-guided musculoskeletal interventional procedures around the shoulder produce better results in terms of accuracy and clinical efficacy than those performed in a blinded fashion. Indeed, intra-articular and peri-articular interventional procedures can be easily performed under continuous ultrasound monitoring to ensure the correct position of the needle and to deliver the medication to a specific target. Several technical approaches and medications can be used to treat different causes of painful shoulder. Intra-articular injections are applied to treat acromioclavicular osteoarthritis as well as glenohumeral joint osteoarthritis and adhesive capsulitis. Subacromial-subdeltoid bursitis, either presenting as a primary inflammatory condition or secondary to rotator cuff disorders, can be easily approached using ultrasound guidance to aspirate synovial effusion and to inject medications. Ultrasound-guided percutaneous irrigation is a well-established technique increasingly applied to treat patients with rotator cuff calcific tendinopathy. Also, degenerative rotator cuff tendinopathy can be conservatively treated by image-guided interventions, specifically with needling under ultrasound guidance that can be associated with injections of platelet-rich plasma. Lastly, periarticular peripheral nerve block can be quickly and safely performed under ultrasound guidance, particularly in conditions involving the suprascapular nerve in the setting of pre-operative analgesia or pain treatment in glenohumeral osteoarthritis and adhesive capsulitis. In this article, the most common ultrasound-guided procedures around the shoulder have been reviewed to discuss indications and techniques.

Proximal vs Distal Approach of Ultrasound-guided Suprascapular Nerve Block for Patients With Adhesive Capsulitis of the Shoulder: Prospective Randomized Controlled Trial

OBJECTIVES

To evaluate the early clinical outcomes of ultrasound (US)-guided suprascapular nerve block (SSNB) using a proximal approach compared with a distal approach for outpatient treatment of adhesive capsulitis.

DESIGN

Randomized controlled trial.

SETTING

Outpatient clinic PARTICIPANTS: Participants (N=47) with symptomatic adhesive capsulitis.

INTERVENTIONS

Participants were randomly assigned to either US-guided SSNB using a proximal approach (n=23, proximal group) or a distal approach (n=24, distal group).

MAIN OUTCOME MEASURES

The primary outcome measure was the visual analog scale (VAS) for pain at week 12. Secondary outcomes included the American Shoulder Elbow Surgeon's (ASES) score, University California Los Angeles score, Short Form-36 mental and physical component summaries, and range of motion. All patients completed clinical follow-up at 2, 6, and 12 weeks after treatment. On US images, depth and insertion angle of needle during injection were measured.

RESULTS

The VAS significantly improved in both groups at week 12. After treatment, no significant differences were found in early clinical outcomes (weeks 2, 6, and 12) between groups (all P>.05), except that ASES at 2 weeks showed a significantly higher score in the distal group than in the proximal group (87.1±4.8 and 83.0±6.3, respectively; P=.014). The mean depth and insertion angle of needle was significantly lower (depth: 13.4±3.9 and 30.6±4.3 mm, respectively; P<.001; insertion angle: 19.6°±6.4° and 38.7°±5.8°; P<.001) in the proximal group than in the distal group.

CONCLUSIONS

This study demonstrated that proximal approach of US-guided SSNB provided favorable short-term outcomes of pain and functional improvement and that outcomes were comparable to those of the distal approach in adhesive capsulitis. The suprascapular nerve was located more superficially and easily identified in the proximal approach, suggesting that this method might improve the accuracy of injection.