Scapular Winging
Article Outline
A 17-year-old boy came to the pediatric neurology clinic with right shoulder pain and “collar bone sticking out” for 2 months. His pain would radiate to the right upper arm and back, and he had difficult lifting his arm above the shoulder. There was no history of weakness of other limbs and no sensory symptoms. He had neck surgery for lymphadenopathy 1 month before onset of his symptoms. On examination, his cranial nerves were intact. He had right shoulder droop and wasting of trapezius muscle (Figure 1; available at www.jpeds.com). There was scapular winging on the right, accentuated on arm abduction (Figure 2). There was limitation of abduction beyond 90 degrees on the right compared with the left (Figure 3). He had right trapezius weakness with preserved sternocleidomastoid. The results of the remainder of his neurological examination, including reflexes and sensation, were normal. He underwent electromyography, by which decreased nerve conduction to trapezius with partial denervation changes and preserved sternocleidomastoid localizing the lesion on the spinal accessory nerve (SAN) distal to the branch supplying sternocleidomastoid were shown. He underwent exploration of the SAN, and with intraoperative testing, nerve continuity was confirmed so nerve grafting was not performed. He had since then partially regained his arm function with physical therapy.
Figure 2
Scapular winging on the right accentuated on arm abduction.
Figure 3
Limitation of abduction beyond 90 degrees on the right compared with the left.
Scapular winging is diagnosed by visible inspection of the scapula, but its etiology is more elusive.1 Scapular winging may be caused by involvement of the serratus anterior (SA), trapezius, or rhomboid muscles. Clinical examination helps to differentiate these conditions.1 In winging caused by SA involvement (from long thoracic nerve palsy), classical or medial scapular winging is usually evident at rest, which can be accentuated when the patient flexes arm to the horizontal plane, pushes on a wall, or both. Winging from trapezius involvement (SAN injury) is typically minimal at rest, but accentuated during arm abduction. In addition, examination elicits an asymmetrical neckline with drooping of the effected shoulder with difficulty in abducting beyond 80 to 90 degrees (as seen in our patient). After rhomboid involvement (dorsal scapular nerve injury) there is subtle winging at rest, which may be accentuated by having the patient extend arm from a fully flexed position.
Common causes of spinal accessory weakness is usually neurogenic because of long thoracic nerve involvement from trauma or after viral infections, with the exception of muscular dystrophies (like fascio-scapulo-humeral dystrophy or limb-girdle-musclar dystrophy), in which case winging is usually bilateral.2 SAN injury commonly results from trauma or iatrogenically from posterior triangle surgeries. The superficial course of SAN in the posterior triangle makes it vulnerable to injury.3 Rhomboid paralysis tends to be primarily neurogenic involving the dorsal scapular nerve.1
Electromyographical testing of all scapulothoracic muscles is essential for correct diagnosis.1 It helps to differentiate neurogenic (nerve injury) and myopathic (muscular dystrophy) causes. Involvement of other muscles around the shoulder girdle helps to differentiate whether it is a more widespread process like brachial plexopathy or muscular dystrophy. This case highlights the role of clinical examination in helping to differentiate various causes of scapular winging.
Appendix.
Figure 1
Right shoulder droop with prominent distal end of clavicle and wasting of lower trapezius muscle.
References
PII: S0022-3476(11)00817-1
doi:10.1016/j.jpeds.2011.08.022
© 2012 Mosby, Inc. All rights reserved.
