Working Diagnosis:
Serratus anterior paralysis due to idiopathic neuralgic amyotrophy (Parsonage-Turner Syndrome) after infectious mononucleosis.

Treatment:
The patient was referred to physical therapy for periscapular strengthening, increasing rotator cuff strength and ROM, and thoracic spine mobility. The patient returned to college out of state.

Phases of physical therapy:
- Acute: Avoid overhead and painful activities; ROM exercises in supine position; do not stretch serratus anterior.
- Intermediate: Once pain subsides, initiate passive stretching of rhomboids, levator scapulae and pectoralis minor to prevent contracture.
- Late: Improve strength of shoulder girdle including trapezius.

Outcome:
On follow-up by phone 10 weeks later, the patient reported completing 7 sessions of physical therapy and compliance with home exercises. He noted subjective improvement of approximately 65% with regard to strength and ROM. He noted that the winged scapula was still present but appeared less prominent.

The patient replaced his normal weightlifting with physical therapy exercises. He will follow a functional progression back to weightlifting once his rotator cuff and periscapular strength is symmetric.

Author's Comments:
Key Points:

- Neuralgic amyotrophy may be an under-recognized cause of scapula winging. Consider this diagnosis in non-traumatic cases of scapula winging associated with severe pain followed by weakness, particularly when preceded by viral illness.

- Winging occurs in distinct patterns. A careful physical exam can help distinguish the specific palsy.

- EMG is essential for confirming muscle involvement and degree of denervation, though this does not predict recovery.

- MRI may be useful in ruling out mass lesion, disk disease or radiculopathy.

- Most cases of serratus anterior palsy resolve within 6-24 months with conservative treatment. Specific physical therapy regimens have been proposed. Patients with persistent paralysis may benefit from surgical intervention.

Editor's Comments:
The occurrence of Parsonage-Turner syndrome has been reported to range between 1.6 and 3 cases per 100,000 annually. However, it is felt to be an under recognized and therefore underdiagnosed condition and some feel the actual incidence rate may be as high as 20-30 cases per 100,000. It is more common in males, with reported ratios ranging from 1.5:1 up to 11.5:1. Preceding viral infection has been the most commonly reported trigger, seen in 20-55% of cases. Other reported risk factors include immunizations, perioperative and peripartum periods, and preceding strenuous exercise. The etiology is unknown, with including autoimmune, genetic, infectious, and mechanical processes having been implicated. The upper trunk of the brachial plexus is most commonly involved. Patchy distribution of motor and sensory symptoms are common. Bilateral involvement may occur in 10-30% of patients. One small study showed that treatment with oral prednisolone hastened recovery.

References:
- Martin RM, Fish DE. Scapular winging: Anatomical review, diagnosis and treatments. Curr Rev Musculoskelet Med. 2008;1(November 2007):1-11.
- Mohanaruban K, Fisher DJ. A combination of cranial and peripheral nerve palsies in infectious mononucleosis. Postgrad Med J. 1986;62:1129-1130.
- Patel DR, Nelson TL. Winging of the Scapula in a Young Athlete. Adolesc Med State Art Rev. 1996;7(3):433-438.
- Porsman O. Isolated paralysis of the serratus anterior muscle. Ugeskr Laeger. 1978;140:2300-2302.
- Vinson EN. Clinical images: scapular winging. Arthritis Rheum. 2006;54:4027.
- Watson CJ, Schenkman M. Physical therapy management of isolated serratus anterior muscle paralysis. Phys Ther. 1995;75:194-202.
- Watson P, Ashby P. Brachial plexus neuropathy associated with infectious mononucleosis. Can Med Assoc J. 1976;114:766-767.
- Tjoumakaris F, Anakwenze O, Kancherla V, Pulos N. Neuralgic amyotrophy (Parsonage-Turner syndrome). J Am Acad Orthop Surg, 20(7), 443-449.
-Smith C, Bevelaqua A. Challenging pain syndromes: Parsonage-Turner syndrome. Phys Med Rehabil Clin N Am 25 (2014) 265-277.

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