Suprascapular Nerve Ablation

The suprascapular nerve, due to its superficial location in the supraspinous fossa, is readily accessible nerve and safe to block. The suprascapular nerve block has been utilized for a number of years to address various causes of shoulder pain. Early advocates of the SSNB reported its usefulness in treating shoulder pain secondary to rotator cuff degenerative tears. Subsequent studies expanded its indications to include conditions such as glenohumeral degenerative joint disease, adhesive capsulitis, and postoperative shoulder pain following arthroscopic surgery.

The suprascapular nerve originates from the upper trunk of the brachial plexus with major contributing fibers from the C5 and C6 nerve roots. It travels posteriorly and laterally toward the supraspinous fossa and enters via the suprascapular notch. Once it reaches the notch, it travels inferior to the superior transverse scapular ligament and laterally toward the base of the coracoid process where it splits into sensory and motor fibers. The suprascapular nerve supplies sensory fibres to about 70% of the shoulder joint, including the superior and posterosuperior regions of the shoulder joint and capsule, and the acromioclavicular joint. In addition it supplies motor branches to the supraspinatus and infraspinatus muscles.

Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered.

The procedure is done on an outpatient basis. The procedure is performed under ultrasound guidance to ensure accuracy of needle placement. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that some patients may need repeat injections.

Generally a mixture of local anaesthetic and steroid is injected. The local anaesthetic is responsible for immediate pain relief, whereas steroids are believed to provide longer-term pain relief. For a diagnostic block, a short-acting anaesthetic alone is sufficient.

Patients who get temporary relief from suprascapular nerve block may be suitable for suprascapular nerve ablation (pulsed radiofrequency treatment). This is likely to provide longer-term pain relief.

The procedure is done on an outpatient basis. The procedure is performed under ultrasound guidance to ensure the accuracy of needle placement. Specialized equipment including radiofrequency machine, probe, and RF needle is utilized to heat the nerve up to a temperature of 42°C. Generally local anaesthetic is injected around the nerve following nerve ablation. The local anaesthetic is responsible for immediate pain relief, whereas pulsed radiofrequency takes 4 to 6 weeks to provided sustained pain relief. Pain relief from pulsed radiofrequency ablation of the suprascapular nerve can last between 6 months to 24 months.

Complications are rare, particularly if the injections are performed using a precise needle-positioning technique. Possible complications include bruising, infection, hematoma, nerve injury and reaction to the injectates. Infection can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. Steroid injections may produce local reactions, occurring most often immediately after injection. These local reactions last for 24 to 48 hours, and are relieved by application of ice packs. Post-procedural pain flare-up may occasionally occur, and may be treated with painkillers. Neurological complications including paraesthesias and numbness have been described but are rare.

Puemothorax has been reported following suprascapular nerve block. The incidence is reported to be less than 1%. Real time ultrasound guidance should help minimize this complication.