Causes / typical injury mechanism: Suprascapular neuropathy (SSN) is usually caused by repetitive traction injury that compresses the suprascapular nerve at the suprascapular and/or spinoglenoid notches. Injury typically occurs in activities that involve forceful overhead motion, including tennis, swimming, volleyball, and weight lifting. Other, secondary etiologies of SSN include scapular dyskinesis; clavicle, proximal humerus, or scapula fracture; glenohumeral instability; acromioclavicular (AC) joint injuries; or a ganglion (or paralabral cyst) arising from the glenohumeral joint that compresses the nerve.

Classic history and presentation: Patients with SSN typically present with weakness of the supraspinatus and/or infraspinatus muscles. They may describe superior and/or posterolateral shoulder pain with variable radiation into the neck or ipsilateral arm. However, if the site of nerve compression is distal to the glenohumeral joint, patients might not experience any pain. There may also be glenohumeral instability or other symptoms from concomitant shoulder pathology.

Prevalence:

• Age – SSN is mainly seen in patients younger than age 40 years. There is a wide prevalence range in athletes from 12%-33% and increased incidence in overhead athletes and workers.
• Sex / gender – While there seems to be no increased prevalence of SSN based on sex, nerve compression due to a ganglion cyst is more often seen in males.

Risk factors: Aside from an increased incidence with forceful repetitive overhead movements, variant anatomy increases the risk of SSN. Deformities in the suprascapular notch including bony prominences, a bifid superior transverse scapular ligament, or a narrowing of the notch can all contribute to increased risk.

Pathophysiology: SSN is typically the result of direct microtrauma to the suprascapular nerve from compression at the suprascapular and/or spinoglenoid notch. Additionally, people who participate in activities with frequent overhead motions are more susceptible to shoulder injury and are likely to have associated instability or rotator cuff injury. Secondary to the onset of SSN or injury, muscle atrophy and degeneration can occur.