A physically fit 26-year-old man presented for evaluation of right shoulder weakness and instability. His symptoms began after starting a weight-lifting program 2 months before presentation. Exercises included repetitive military presses and leverage incline chest presses with high resistance. He initially noticed “aching and burning” at the superior and posterior aspect of the right shoulder, which gradually progressed to include shoulder weakness with overhead motion and instability. His pain interfered with sleep and was worse at the end of the day. After 4 to 6 weeks, the pain resolved, but the patient continued to have weakness and instability of his shoulder. He reported occasional faint aching and tingling sensations radiating into the proximal arm but not distal to the elbow.
Initial examination of the musculoskeletal system revealed postural deficiency with forward-positioned head and anteriorly rolled shoulders, normal muscle bulk and tone, and no tenderness on palpation to the cervical, thoracic, or lumbar regions. Tissue texture changes and taut bands were present along the right medial border of the scapula. Examination of the right shoulder revealed a painless restricted range of motion of flexion and abduction to approximately 145° in the sagittal and coronal planes, respectively. Scapula assessment with SICK (scapular malposition, inferior medial border prominence, coracoid pain/malposition, and dyskinesis of movement) demonstrated scapular dyskinesis and prominent medial winging (
Figure 1,
eVideo). A positive scapular assist maneuver eased the action of full overhead abduction. Serratus anterior function, which is the primary scapular protractor, can be adequately assessed with the wall push-up.
7 In the present case, a wall push-up further demonstrated medial scapular winging with marked prominence of the medial scapular border (
Figure 2,
eVideo). Neurologic examination demonstrated 5/5 strength throughout the major muscle groups of the upper extremity, including the rotator cuff. The remainder of the physical examination demonstrated grossly intact sensation to light touch, negative Spurling maneuver bilaterally, negative Hoffman test bilaterally, and grossly intact cranial nerves II through XII.
The leading differential diagnosis was mononeuropathy of the long thoracic nerve secondary to overhead weight lifting. The expanded differential diagnosis included rotator cuff tear, SICK scapula, glenohumeral instability, SLAP (superior labral from anterior to posterior) tear, acromioclavicular disease, biceps tendonitis, Parsonage Turner syndrome (brachial neuritis, neuralgic amyotrophy), and scapular osteochondroma. Right upper extremity electromyography (EMG) and a nerve conduction study (NCS) were ordered to assess the long thoracic nerve and periscapular musculature, and standard radiographic imaging of the shoulder and scapula were ordered to rule out osseous abnormality.
The EMG found evidence of a right long thoracic nerve injury by increased insertional activity with positive sharp waves and fibrillations in the serratus anterior on the right, which indicated active denervation. The remainder of muscles tested demonstrated normal insertional activity and motor unit action potential configuration. Results of motor NCSs of the right long thoracic, median, and ulnar nerves as well as the left long thoracic nerve were normal. No electrodiagnostic evidence of cervical radiculopathy, brachial plexopathy, or peripheral neuropathy was found in the right upper extremity. The shoulder/scapular radiographs revealed no remarkable findings. The results confirmed the diagnosis of long thoracic nerve injury resulting in scapular dyskinesis.
A conservative treatment plan was initiated and included an active scapular physical therapy program focusing on strengthening the serratus anterior, lower-middle trapezius, and rhomboid muscles, with a focus on functional tasks with proper scapular positioning and integration of closed kinetic chain exercises. The program also included stretching of the anterior chain, specifically the pectoralis minor muscle, education on home exercises, and rib mobilization. A follow-up appointment was scheduled at 6 weeks.