1. Intrinsic causes (by age):
Adolescents and young adults:
Overuse injuries
Acromioclavicular sprain
Shoulder instability
Middle-aged and older individuals:
Rotator cuff tendinopathy, tears or impingement syndrome
Subacromial bursitis or inflammatory synovitis
Adhesive capsulitis (frozen shoulder)
Bicipital tendinitis
Osteoarthritis of glenohumeral or acromioclavicular joints
Myofascial pain
2. Extrinsic causes (by anatomic associations):
Neurologic:
Spinal cord lesion
Cervical spine disease
Cervical nerve (C5, C6) root compression
Suprascapular nerve compression
Brachial plexus lesions
Herpes zoster
Abdominal:
Abdominal referred pain (hepatobiliary dz)
Diaphragmatic irritation (splenic injury, ruptured ectopic pregnancy, perforated bowels)
Cardiovascular:
Cardiovascular referred pain (MI)
Axillary vein thrombosis
Thoracic outlet syndrome
Thoracic:
Upper lobe pneumonia
Apical lung tumor
PE
Contributor
Peter Zhang, MD.