Suprascapular Nerve Block

Indications and Clinical Considerations

Suprascapular nerve block with local anesthetic can be used as a diagnostic tool when performing differential neural blockade on an anatomic basis in the evaluation of shoulder girdle and shoulder joint pain. If destruction of the suprascapular nerve is considered, this technique is useful as a prognostic indicator of the degree of motor and sensory impairment that the patient may experience. Suprascapular nerve block with local anesthetic may be used to palliate acute pain emergencies, including postoperative pain, pain secondary to traumatic injuries of the shoulder joint and girdle, and cancer pain, while waiting for pharmacologic, surgical, and antiblastic methods to become effective. Suprascapular nerve block also is useful as an adjunctive therapy when treating the decreased range of motion of the shoulder secondary to reflex sympathetic dystrophy or adhesive capsulitis. Suprascapular nerve block also can be used to allow more aggressive physical therapy after shoulder reconstruction surgery. It also is useful as both a diagnostic and therapeutic maneuver in the management of suprascapular nerve entrapment syndrome ( Fig. 46.1 ). Destruction of the suprascapular nerve is indicated for the palliation of cancer pain, including invasive tumors of the shoulder girdle. This block can be performed in patients who are receiving anticoagulant therapy if the clinical situation dictates a favorable risk-to-benefit ratio.

FIG. 46.1, Ultrasound image demonstrating a cyst in the spinoglenoid notch that is compressing the suprascapular nerve.

Plain radiographs are indicated for all patients with shoulder pain. Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging and/or ultrasound imaging of the shoulder is indicated if suprascapular nerve entrapment is suspected because both may not only demonstrate the cause of the nerve entrapment but may also identify secondary atrophy of the infraspinatus muscle ( Figs. 46.2 and 46.3 ).

FIG. 46.2, Posterosuperior impingement syndrome in a patient aged 35 years with the formation of a spinoglenoid cyst compressing a terminal branch of the suprascapular nerve. A and B, Magnetic resonance imaging shows tendinopathy of the supraspinatus, posterosuperior labral rupture, a cyst at the spinoglenoid notch (white arrow), and patchy edema of the infraspinatus muscle (white arrowhead) probably related to compression of some terminal branch of the suprascapular nerve. C–E, Computed tomographic arthrography showing labral rupture (black arrow), the cyst (white arrow), and small geodes of the humeral head penetrated by contrast medium (black arrowhead).

FIG. 46.3, Old neuropathy (probably 5 years) of the suprascapular nerve at the spinoglenoid notch. A and B, Ultrasound and sagittal T1 image showing severe muscle damage restricted to the infraspinatus (arrow). Such phenomena are rare in neuropathies. In most cases, the fatty involution remains moderate.

Clinically Relevant Anatomy

The suprascapular nerve is formed from fibers originating from the C5 and C6 nerve roots of the brachial plexus with some contribution of fibers from the C4 root in most patients. The nerve passes inferiorly and posteriorly from the brachial plexus to pass underneath the coracoclavicular ligament and then beneath the superior transverse ligament as it passes through the suprascapular notch ( Figs. 46.4 and 46.5 ). The suprascapular artery and vein accompany the nerve through the suprascapular notch (see Figs. 46.4 and 46.5 ). The suprascapular nerve provides much of the sensory innervation to the shoulder joint and provides innervation to 2 of the muscles of the rotator cuff: the supraspinatus and infraspinatus. The suprascapular nerve also provides an articular branch to the acromioclavicular joint.