From Frozen Shoulder to Nerve Injury: Recognizing Suprascapular Neuropathy in Adhesive Capsulitis

Vollständiger Abstract

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Introduction: Adhesive capsulitis (AC), or frozen shoulder, is a chronic condition characterized by progressive pain and restricted movement due to capsular fibrosis. While its impact is primarily articular, long-standing biomechanical alterations can predispose to secondary complications. Suprascapular neuropathy is an uncommon complication, presenting with weakness and atrophy of supraspinatus and infraspinatus muscles. Case: A 48-year-old man with a 3-month history of left-sided AC presented to the neurology clinic for electrophysiologic evaluation due to weakness and shrinking of left upper back muscle. Initially, he reported severe shoulder pain which has subsided with physiotherapy and pain intervention. Physical examination revealed marked left infraspinatus muscle atrophy and external rotation weakness. Electromyography (EMG) revealed suspected left suprascapular neuropathy. Discussion: Although studies on the direct causation between AC and suprascapular neuropathy are rare, this case illustrates the potential for long-standing AC to cause neuropathy via secondary mechanisms of chronic altered shoulder biomechanics leading to possible entrapment at anatomical narrowings. Restricted glenohumeral motion in AC causes compensatory reliance on scapulothoracic movement, imposing abnormal tension on the suprascapular nerve (SSN) at the spinoglenoid notch. Absence of sensory abnormality and normal supraspinatus muscle in EMG implies isolated distal SSN compression at the notch. Conclusion: Recognition of muscle atrophy and weakness with targeted electrophysiological assessment for suprascapular neuropathy in AC are essential, as clinical presentation may be overshadowed by the primary joint pathology. This report showcases a rare occurrence of EMG-confirmed suprascapular neuropathy in AC, emphasizing that timely management of inflammation reduction, physical and occupational therapy will not only restore shoulder mobility but also prevent secondary complications like suprascapular neuropathy.