The presence of functional scapular winging is typically due to a simple imbalance of otherwise healthy muscles. But approximately 5% of cases are due to more significant pathology like nerve injury- particularly the long thoracic nerve. (1) Differentiating the source of dysfunction is paramount in managing shoulder complaints.
The long thoracic nerve originates from branches of the C5 and C6 nerve roots. These branches join beneath the middle scalene muscle and with some variability, either pierce the middle scalene or emerge between the middle and anterior scalene before uniting with a branch of the C7 (and sometimes C8) nerve root. The long thoracic nerve travels through the axilla to innervate the serratus anterior muscle- a shoulder protractor and scapular stabilizer. Injury to the long thoracic nerve denervates the serratus anterior muscle, resulting in scapular winging and shoulder instability.
The long thoracic nerve may be injured from blunt trauma; however, the most common etiology seems to result from repetitive compression or traction. Over 1/3 of cases develop secondary to athletic activity, particularly during exercise or sports that require middle scalene activation. Activities that entail contralateral cervical rotation combined with ipsilateral arm elevation cause significant stretch to the long thoracic nerve.
Long thoracic nerve palsy often follows strenuous upper extremity activity or heavy weight lifting. Symptoms typically include:
- Arm pain and rapid fatigue
- Weakness or instability when pushing, pulling, and lifting, particularly with the arm above shoulder level
- Up to half of patients affected are unable to flex or abduct their shoulder beyond 90 degrees
Clinical evaluation will typically demonstrate scapular winging with inferior angle prominence. Check out the attached video to learn two useful tests for differentiating the source of scapular winging.
Because Long thoracic nerve palsy is relatively rare, diagnosis is often delayed for months or years. The prognosis for long thoracic neuropathy is quite variable with some authors reporting spontaneous recovery while other cases fail to respond to any treatment, including surgery. Initial management is typically conservative. Patients often show some degree of recovery within the first six to 12 months; however, complete recovery is not always achieved. Nerve flossing exercises may be employed; but clinicians should avoid aggressive or excessive stretch that could exacerbate the injury. Myofascial release and stretching should be directed at the scalene muscles. Patients should perform scapular stabilization exercises beginning in a supine position.
Approximately 30% of patients fail conservative management. Surgical intervention may be considered when symptoms persist despite an extended trial of conservative care. Surgical intervention typically involves nerve release. Surgical outcomes tend to deteriorate in relation to chronicity. Patients who have suffered for greater than 10 years are typically candidates for scapular stabilization surgery vs. nerve release.
To learn more about the simple muscular imbalances that cause the other 95% of scapular dyskinesis presentations, check out this ChiroUp Clinical Excellence tutorial.
1. Shailen Woods Comprehensive Approach to the Management of Scapular Dyskinesia in the Overhead Throwing Athlete. UPMCPhysicianResources.com/Rehab
About the Author
Dr. Brandon Steele
Dr. Steele began his career at The Central Institute for Human Performance. Dr. Steele has trained with experts including Pavel Kolar, Stuart McGill, Brett Winchester, and Clayton Skaggs. He has been certified in Motion Palpation, DNS, ART, and McKenzie Therapy. Dr. Steele lectures extensively on clinical excellence and evidence-based musculoskeletal management. He currently practices in Swansea, IL and serves on the executive board of the ICS.
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