An Isolated Long Thoracic Nerve Injury in a Navy Airman

Military Medicine, Sep 2004 by Oakes, Michael J, Sherwood, Daniel L

A palsy of the long thoracic nerve of Bell is a cause of scapular winging that has been reported after trauma, surgery, infection, electrocution, chiropractic manipulation, exposure to toxins, and various sports-related injuries that include tennis, hockey, bowling, soccer, gymnastics, and weight lifting. Scapular winging can result from repetitive or sudden external biomechanical forces that may either exert compression or place extraordinary traction in the distribution of the long thoracic nerve. We describe an active duty Navy Airman who developed scapular winging secondary to traction to the long thoracic nerve injury while working on the flight line. A thorough history and physical is essential in determining the mechanism of injury. Treatment should initially include refraining from strenuous use of the involved extremity, avoidance of the precipitating activity, and physical therapy to focus on maintaining range of motion and strengthening associated muscles, with most cases resolving within 9 months.

Introduction

Serratus anterior paralysis attributable to injury of the long thoracic nerve was first described in the literature by Velpeau1 (in 1837 as winging of the scapula known as scapula alata).2 In serratus anterior palsy, the pain and deformity at rest are minimal, with slight winging of the lower portion of the scapula. The lower part of the medial border of the scapula is closer to the vertebral column due to the action of the rhomboids and levator scapulae. Winging of the scapula becomes more prominent on forward elevation of the arm. The scapula moves upward and laterally during this movement, with the inferior angle displaced farther from the midline than the superior angle.3

Etiologies of injury to the long thoracic nerve include entrapment of the fifth and sixth cervical roots as they pass through the scalenus m�dius muscle, compression of the nerve by the undersurface of the scapula as the nerve crosses over the second rib during traction to the upper extremity, and compression and traction to the nerve by the inferior angle of the scapula during general anesthesia or passive abduction of the arm.4'8 Surgical injury to the long thoracic nerve may occur during mastectomy, radical neck dissection, or thoracotomy.9 The specific occupational occurrence seen in our patient has not been previously investigated.

case Report

A 21-year-old right-handed white male Navy Airman presented with chief complaints of right-sided neck pain, right shoulder weakness and discomfort, along with severely diminished upper arm range of motion. There was no radiation of symptoms into the arm, forearm, wrist, or hand. There was no history of recent viral infection, immunization, excessive weight training, sports injury, chiropractic manipulation, shoulder or thorax surgery, or family history of similar complaints. Inhisjob on the flight line, he would run carrying a 60-pound aircraft hydraulic servicing unit on his right shoulder, then swing it behind his back to the ground like swinging a bowling ball. During this maneuver, he felt a pop in his shoulder. After 1 week of pain symptoms, weakness and scapular deformity became apparent. He was well conditioned at 75 inches and weighed 165 pounds.10 There was no past medical history of right shoulder problems.

Physical examination showed normal neck and shoulder musculature except for atrophy of the right serratus anterior and deltoid muscles. There was protuberance, or winging, of the medial border of the right scapula. This was accentuated by forward flexion of the right arm, increased considerably when he pushed against a wall (Fig. 1). At rest, the right scapula appeared to exhibit a tilt inferomedially, with the inferior tip being prominent. The left scapula appeared to be normal. Range of motion and function of the neck was normal with some mild right-sided paraspinal muscular pain. Passive range of motion of the right shoulder was normal, whereas active range of motion revealed a limitation of abduction to approximately 90� and flexion to 110�. He exhibited a decrease in muscle strength on resisted abduction and forward flexion of the right arm. Stabilization of the right scapula to the thoracic wall enabled him to abduct his arm to 110� and flex to 150�, as well as improved his strength. His C5, C6, and C7 deep tendon reflexes were 2 bilaterally.

Electromyography performed 8 weeks after the onset of symptoms demonstrated numerous fibrillations and positive sharp waves in the right serratus anterior muscle, confirming a right long thoracic nerve palsy. Maximum patient effort with this muscle was reduced. All other cervical paraspinal and upper extremity muscles were electrically normal. The scapular winging was thought to be primarily due to serratus anterior muscle weakness.

The patient was treated conservatively with enrollment in a physical therapy program focusing on stretching, range of motion, and strengthening of trapezius, rhomboids, and levator scapulae, gradually increasing the amount of weight used. Medication therapy included short-term narcotics, gabapentin and nonsteroidal anti-inflammatory drugs. He has been progressing well with gradual return of shoulder strength, although winging is still apparent.