Long Thoracic Nerve Injury Caused by Overhead Weight Lifting Leading to Scapular Dyskinesis and Medial Scapular Winging Justin B

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CASE REPORT

Long Thoracic Nerve Injury Caused by Overhead Weight Lifting Leading to Scapular Dyskinesis and Medial Scapular Winging Justin B. Berthold, DO Timothy M. Burg, DO Ryan Paul Nussbaum, OMS IV

From the Rehabilitation Scapular winging represents a rare phenomenon that most commonly re- Physicians of Pittsburgh sults from nerve damage to either the long thoracic nerve, spinal accessory in Pennsylvania (Drs Berthold and Burg) nerve, or, less commonly, the dorsal scapular nerve. This injury results in and the Lake Erie College an abnormal scapulohumeral interaction during kinetic motion known as of Osteopathic Medicine in scapular dyskinesis. In this case report, the patient presented with scapular Erie, Pennsylvania (Student Doctor Nussbaum). dyskinesis and medial scapular winging caused by overhead weight-lifting

Financial Disclosures: exercises, and a long thoracic nerve injury was diagnosed. Physicians are None reported. encouraged to consider long thoracic nerve damage in a patient with a his-

Support: None reported. tory of repetitive overhead movements who presents with scapular dyski-

Address correspondence to nesis and the corresponding restriction of overhead arm motions. Potential Justin B. Berthold, DO, mechanisms of injury and treatment options are also discussed. Rehabilitation Physicians of J Am Osteopath Assoc. 2017;117(2):133-137 Pittsburgh in Pennsylvania, doi:10.7556/jaoa.2017.025 21 Yost Blvd, 144 Forest Hills Plaza, Keywords: long thoracic nerve injury, scapular dyskinesis, scapular winging Pittsburgh, PA 15221

Email: rehabphysiciansofpgh@ gmail.comSubmitted capular winging can markedly hinder the function of the upper extremity. Nerve damage represents the most common cause, most often to the long thoracic March 10, 2016; nerve or the spinal accessory nerve.1 Additional causes of scapular winging final revision received S July 21, 2016; include direct trauma to the scapulothoracic muscles or structural abnormalities that accepted result in shoulder instability. Medial winging of the scapula manifests with damage to September 13, 2016. the long thoracic nerve, and lateral winging occurs with damage to the spinal accessory nerve or the dorsal scapular nerve, although the latter is less common. Serratus anterior paralysis is not a common comorbidity, with 1 case of long thoracic nerve damage among 38,500 patients with this condition.2 Seventeen different muscles attach to the scapula. The serratus anterior and lower trapezius muscles are the major contributors to the stabilization of the scapula during arm movement.3 This stability plays an integral role in abduction of the arm: until 30° to 60°, the proportion of humeral elevation to scapular elevation is approximately 8:1, and then it continues in a 2:1 ratio of glenohumeral to scapulothoracic motion for the rest of the abduction arc.4 Hence, scapular winging can substantially hinder overhead arm movements. Scapular dyskinesis refers to any alteration of the typical kinematics of the scapula ► Video available during scapulohumeral movements. Nerve damage represents one of the many causes online of this condition.5 Scapular dyskinesis seems to be most prevalent in athletes who routinely perform overhead motions, such as volleyball players and baseball players.6 The current patient presented with scapular dyskinesis and medial scapular winging caused by overhead weight-lifting exercises.

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

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specifically the pectoralis minor muscle, education on home exercises, and rib mobilization. A follow-up appointment was scheduled at 6 weeks.

Discussion In athletes, damage to the long thoracic nerve commonly occurs when there is traction on the arm in the overhead position with the neck turned to the contra- lateral direction.8 Actions such as throwing a baseball or taking a breath during freestyle swimming Figure 1. may increase the risk of damage to the long thoracic Scapula assessment with SICK (scapular malposition, nerve. The current patient’s weight-lifting program inferior medial border prominence, coracoid pain/ included repetitive military presses and leverage in- malposition, and dyskinesis of movement) demonstrated scapular dyskinesis and prominent medial winging in a cline chest presses. Military presses require an over- patient with long thoracic nerve injury caused by overhead head lift of weight, and it can be varied to incorporate weight lifting. both arms simultaneously or 1 at a time. Depending on the height of the incline, the leverage incline press can also incorporate a press movement greater than 90° from the trunk of the body. Both actions can in- jure the long thoracic nerve. The type of nerve injury in the current patient was classified as axonotmesis because denervation potentials were found on needle examination. However, some motor axons were still intact, indicated by a compound motor action potential found during the NCS. This finding led us to believe that the patient had a good prognosis, owing to the intact perineurium and epineurium. A good prognosis is implied with an axonotmesis nerve in- Figure 2. jury as long as the distance between the lesion site Wall push-up demonstrated medial scapular winging with and end organ is not too long.9 marked prominence of the medial scapular border in a patient with long thoracic nerve injury caused by overhead A few key factors explain how we arrived at the weight lifting. diagnosis of long thoracic nerve injury despite the normal results on motor NCS. The EMG showed increased insertional activity with positive sharp waves and fibrillation potentials in the serratus ante- electrodes. The serratus anterior is a large muscle rior muscle. These findings are indicative of active spanning multiple intercostal levels; therefore, it is denervation. During the NCS, the long thoracic possible that the electrodes were placed over intact nerve was assessed by stimulating the Erb point and endplate zones and not directly over an area of de- recording over the serratus anterior with surface nervation. We determined that the data collected

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during the EMG portion of the study provided com- Rehabilitation, as in the current case, should focus pelling evidence to confirm denervation of the long on alleviating the scapular dyskinesis with proper thoracic nerve, as there is no other physiologic basis strengthening exercises for the muscles that stabilize for the presence of positive sharp waves and fibrilla- the scapula. Patients should also be encouraged to tion potentials within the serratus anterior muscle. undergo osteopathic manipulative treatment, in- Therefore, further NCSs were deemed unnecessary cluding correction of somatic dysfunction in the cer- for confirmation of the diagnosis. vical, thoracic, rib, and upper extremity regions. Rib The long thoracic nerve originates from C5-C7. motion should be assessed with suspected exhalation Cervical vertebrae 5-6 nerve branches pass through dysfunction of ribs 6 to 9 (normal bucket handle mo- the scalenus medius and merge with C7 nerve branches, tion), which could result from the impaired activation which travel anterior to the scalenus medius.10-12 of the serratus anterior. Additional techniques include The path continues to pass over the first rib and then inhibition of myofascial tenderpoints along the right enters a fascial sheath and travels down the lateral medial scapular border and scapular mobilization, component of the thoracic wall to the serratus ante- supine pectoral traction, and thoracic mobilization to rior.10,12,13 This long course, averaging a total length of facilitate correction of postural derangement. 24 cm, is hypothesized to be a reason for an increased Consistent follow-up with patients who have long susceptibility to mechanical damage.14 Although it is thoracic nerve injury is necessary during the thera- difficult to establish a consensus on where the lesion peutic process to maximize the potential for func- typically occurs, one mechanism suggests a traction tional recovery. injury, which occurs when the long thoracic nerve exits the fascial sheath that encompasses it along the thoracic wall.13 Another plausible mechanism involves Conclusion chronic and repetitive overhead arm raising that ends Although it is a rare phenomenon, an injury to the up lengthening and potentially fraying the long long thoracic nerve should be included in the differ- thoracic nerve. One study demonstrated doubling of ential diagnosis for a patient with scapular dyski- the length of the long thoracic nerve in cadavers by nesis and medial scapular winging. If the patient also putting the cadavers’ arms overhead with the head has a history of participating in activities that require simultaneously tilted laterally away from the involved repetitive motions of the arm in the overhead posi- shoulder.1 An additional mechanism involves the sca- tion, the likelihood of damage to the long thoracic lenus medius going into spasm, compressing the long nerve is greater. thoracic nerve, and reducing conduction.1 Initial treatment should involve a conservative, non- References 1. Martin RM, Fish DE. Scapular winging: anatomical review, 8 surgical approach. The general consensus is to allow diagnosis, and treatments. Curr Rev Musculoskelet Med. 6 to 24 months of conservative treatment, because most 2008;1(1):1-11. doi:10.1007/s12178-007-9000-5 cases spontaneously resolve during this time.10,15 2. Overpeck DO, Ghormley RK. Paralysis of the serratus magnus muscle caused by lesion of the long thoracic nerve. Axonal regeneration is typically estimated to occur JAMA. 1940;114:1994-1996.

at a rate of 1 mm per day, but it can vary. A lack of im- 3. Kibler WB, Sciascia A. Current concepts: scapular provement after 24 months may indicate that paralysis dyskinesis. Br J Sports Med. 2010;44(5):300-305. doi:10.1136/bjsm.2009.058834 is permanent; in that case, surgical intervention is the 4. McQuade KJ, Smidt GL. Dynamic scapulohumeral rhythm: best course of action.10,15 the effects of external resistance during elevation of the arm

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in the scapular plane. J Orthop Sports Phys Ther. 10. Gregg JR, Labosky D, Harty M, et al. Serratus anterior 1998;27(2):125-133. doi:10.2519/jospt.1998.27.2.125 paralysis in the young athlete. J Bone Joint Surg. 1979;61(6A):825-832. 5. Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 11. Wiater JM, Flatow EL. Long thoracic nerve injury. 2003;11:142-151. Clin Orthop Relat Res. 1999;368:17-27.

6. Woods S, Chimes GP, Burnett T. Comprehensive 12. Hester P, Caborn DN, Nyland J. Cause of long thoracic approach to the management of scapular dyskinesia nerve palsy: a possible dynamic fascial sling cause. in the overhand throwing athlete. UPMC Rehab J Shoulder Elbow Surg. 2000;9(1):31-35. Grand Rounds. Fall 2012:1-8. 13. Ebraheim NA, Lu J, Porshinsky B, Heck BE, Yeasting RA. 7. Hoppenfeld S. Physical Examination of the Spine Vulnerability of the long thoracic nerve: an anatomic study. & Extremities. Upper Saddler River, NJ: Prentice Hall; J Shoulder Elbow Surg. 1998;7(5):458-461. 1976:30. 14. Teboul F, Bizot P, Kakkar R, Sedel L. Surgical management 8. Aval SM, Durand P Jr, Shankwiler JA. Neurovascular of trapezius palsy. J Bone Joint Surg. 2004;86A(9):1884-1890. injuries to the athlete’s shoulder: part I [review]. 15. Foo CL, Swann M. Isolated paralysis of the serratus J Am Acad Orthop Surg. 2007;15(4):249-256. anterior: a report of 20 cases. J Bone Joint Surg. 9. Dumitru D, Amato AA, Zwarts J. Electrodiagnostic Medicine. 1983;65(5):552-556. 2nd ed. Philadelphia, PA: Hanley & Belfus; 2002:125. © 2017 American Osteopathic Association

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