Trapezius Muscle Palsy / Spinal Accessory Nerve Palsy
The trapezius muscle is the the large muscle between your neck and your shoulder. It forms the ‘V’ shape of your neck. The trapezius muscle lifts the shoulder blade. It is the muscle which you use to shrug your shoulders, as well as assisting in moving your arm overhead.
Trapezius muscle wasting on the right side
Trapezius muscle weakness and wasting is usually the result of inury to the nerve which makes the muscle work, known as the Spinal Accessory nerve. This nerve may be injured after surgery on the nect (eg. Lymph node biopsy, parotid surgery, carotid surgery). It might be injured by a direct blow to the neck or wrenching injury to the arm or neck.
The natural history depends on the cause of the nerve palsy. Blunt trauma or traction injury may recover within 12 months. However, penetrating trauma or laceration of the nerve generally does not recover and requires early surgical intervention.
If disabling pain and inability to fully elevate the arm overhead is present surgery should be considered once non-operative treatments have failed (physiotherapy and pain-killers).
Surgical treatment involves transferring other muscles to replace the function of the trapezius muscle. The muscles used are usually levator scapulae and rhomboids. This is known as the Eden-Lange Procedure.
If this muscle transfers fail to obtain adequate stability or range of motion, scapulothoracic fusion is the salvage procedure of choice. Patients who have heavy demands for their shoulders may benefit from scapulothoracic fusion as the primary procedure of choice. Surgery, however, is generally for functional activities of daily living and is generally not adequate for return to sports activity.
Results of surgery suggest 59% excellent results, 27% satisfactory and 14% unsatisfactory results. Adequate pain relief has been noted in 91% of patients undergoing the Eden-Lange procedure, and significant functional improvement was noted in 87%. After surgery, patients should be able to elevate the extremity above the horizontal plane with enough strength for functional activity and had no pain or only slight pain after strenuous activity.