Winged Scapula Syndrome
Winged scapula syndrome is an uncommon cause of musculoskeletal pain of the shoulder and posterior chest wall. Caused by paralysis of the serratus anterior muscle, winged scapula syndrome begins as a painless weakness of the muscle with the resultant pathognomonic finding of winged scapula. As a result of dysfunction secondary to paralysis of the muscle, musculoskeletal pain often results.
Winged scapula syndrome is often initially misdiagnosed as strain of the shoulder groups and muscles of the posterior chest wall because the onset of the syndrome often occurs after heavy exertion, most commonly after carrying heavy backpacks. The syndrome may coexist with entrapment of the suprascapular nerve.
Trauma to the long thoracic nerve of Bell is most often responsible for the development of winged scapula syndrome. Arising from the fifth, sixth, and seventh cervical nerves, the nerve is susceptible to stretch injuries and direct trauma. The nerve is often injured during first rib resection for thoracic outlet syndrome. Injuries to the brachial plexus or cervical roots also may cause scapular winging, but usually in conjunction with other neurological findings. Trauma to the serratus anterior muscle and facial entrapment of the long thoracic nerve of Bell can also cause winging of the scapula.
The pain of winged scapula syndrome is aching and is localized to the muscle mass of the posterior chest wall and scapula. The pain may radiate into the shoulder and upper arm. The intensity of the pain of winged scapula syndrome is mild to moderate, but it may produce significant functional disability, which, if untreated, continues to exacerbate the musculoskeletal component of the pain.
What are the Symptoms of Winged Scapula Syndrome
Regardless of the mechanism of injury to the long thoracic nerve of Bell, the common clinical feature of winged scapula syndrome is paralysis of the scapula resulting from weakness of the serratus anterior muscle. The pain of winged scapula syndrome generally develops after the onset of acute muscle weakness, but it is often erroneously attributed to overuse during vigorous exercise.
On physical examination, the last 30 degrees of overhead arm extension is lost and the scapular rhythm is disrupted. By having the patient press the outstretched arms against a wall, the scapular winging is easily viewed by the clinician observing the patient from behind. The remainder of the patient’s neurological examination should be within normal limits.
How is Winged Scapula Syndrome diagnosed?
Owing to the ambiguity and confusion surrounding this clinical syndrome, testing is important to help confirm the diagnosis of winged scapula syndrome. Electromyography helps distinguish isolated damage to the long thoracic nerve of Bell associated with winged scapula syndrome from brachial plexopathy. Plain radiographs are indicated in all patients who present with winged scapula syndrome to rule out occult bony pathological processes. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging (MRI) and ultrasound imaging of the brachial plexus, cervical spine, or both is indicated if the patient exhibits other neurological deficits.
Lesions of the cervical spinal cord, brachial plexus, and cervical nerve roots can produce clinical symptoms that include winging of the scapula. Such lesions also should produce additional neurological findings that allow the clinician to distinguish these pathological conditions from the isolated neurological findings seen in winged scapula syndrome. Pathology of the scapula or shoulder group also may confuse the clinical diagnosis.
No specific treatment for winged scapula syndrome exists other than removal of the cause of nerve entrapment (e.g., heavy backpacks or tumor compressing a nerve) and use of an orthotic device to help stabilize the scapula to allow normal shoulder function. Initial symptomatic relief of the pain and functional disability associated with winged scapula should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold also may be beneficial. Repetitive movements or movements that incite the syndrome should be avoided.
The major complications associated with winged scapula syndrome fall into two categories: (1) damage to the shoulder resulting from the functional disability associated with the syndrome and (2) failure to recognize that the cause of winging of the scapula is the result not of an isolated lesion of the long thoracic nerve of Bell but rather a part of a larger neurological problem.
Winged scapula syndrome is a distinct clinical entity that is difficult to treat. Early removal of the offending cause of nerve entrapment should allow rapid recovery of nerve function with resultant improvement in pain and shoulder dysfunction.
A careful search for other causes of winging of the scapula should occur before attributing this neurological finding to winged scapula syndrome.