Scapular Winging Secondary to Iatrogenic Spinal Accessory Nerve Lesions

Motor innervation of trapezius and sternocleidomastoid (SCM) muscles is provided solely by the spinal accessory nerve (SAN). SAN palsy most often occurs as a result of iatrogenic injury to the nerve. A patient, who had undergone neck dissection for thyroid cancer, presented with pain and reduced range of motion of the shoulders. Electroneuromyography revealed denervation of the trapezii and SCM muscles secondary to SAN injury. The patient was treated with a course of physical therapy (PT). This case reminds us that a SAN lesion should be considered in the differential diagnosis of a patient presenting with shoulder pain following surgery of the neck. Even though unilateral SAN injury can eventually lead to atrophy of the trapezius, muscle asymmetry may not be obvious, especially in bilateral iatrogenic SAN injuries. In our experience, these patients benefit from PT. However, evidence to support the use of PT in the treatment of shoulder dysfunction secondary to SAN injury is insufficient; the optimum type and timing of PT requires further investigation. Development of best-practice guidelines in terms of management is necessary. Key Words: Spinal accessory nerve, Electroneuromyography, Scapular winging.