Working Diagnosis:
LEFT spinal accessory nerve palsy of moderate severity
Secondary diagnosis
Unrelated ulnar neuropathy of LEFT hand

Treatment:
She had conservative management including rest, ice, compression and elevation. She was advised to take non-steroidal anti-inflammatory medications as needed. Electrical stimulation was continued but cupping and dry needling were discontinued. She was also given a home exercise program and formal physical therapy to work on shoulder strengthening and stabilization.

Outcome:
After 4 months there was no improvement in her abductor weakness, shoulder droop, atrophy or scapular winging. She underwent repeat nerve conduction studies and electromyography at that time which were unchanged from her prior studies. She also underwent magnetic resonance imaging of her cervical spine and computerized tomography with contrast of her neck that did not demonstrate another etiology of her symptoms.

Author's Comments:
The spinal accessory nerve (CN XI) exits the skull from the greater foramen and descends along the neck and shoulder girdle. It returns and converges with C2/C3 at the occiput. It provides motor branches to the sternocleidomastoid muscle proximally and the trapezius muscle distally. It has a superficial course making it vulnerable to direct injury. It is primarily injured iatrogenically and can be injured secondarily due to blunt or penetrating trauma. It can be affected by some motor neuron diseases. However, the atraumatic nature of injury in this case is unusual.

Editor's Comments:
Spinal accessory nerve injury most commonly occurs as a result of surgical trauma in the posterior triangle of the neck where it combines with the second and third cervical nerves. This can occur during a procedure such as a lymph node biopsy. Given the superficial course, it can also be vulnerable to stretch injury. There are case reports of compression injury from climbing and carrying a heavy backpack. It primarily has motor function so no sensory changes would be expected with this type of injury. One test for spinal accessory nerve injury is a positive scapular flip sign where medial scapular border lifts from the thoracic cage during resisted external rotation of the shoulder.

References:
Coulter JM, Warme WJ. Complete Spinal Accessory Nerve Palsy From Carrying Climbing Gear. Wilderness Environ Med. 2015 Sep;26(3):384-6. doi: 10.1016/j.wem.2015.03.028. Epub 2015 Apr 30. PMID: 25937552.

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