Am Fam Physician. 2015 Oct 15;92(8):725-726.
A healthy 18-year-old man with no significant medical history presented with right shoulder weakness and pain that had been present for one week. He had recently started a daily intensive physical fitness regimen similar to military boot camp. The week before his symptoms began, he had a particularly grueling workout session that involved multiple repetitions of push-ups, inchworms, and bear crawls that the patient found difficult to complete.
He had weakness in his right arm and could not lift it over his head, and he had dull, achy pain in his right shoulder. He had no numbness or tingling. He noticed that his right shoulder blade was protruding compared with the left side.
The examination revealed an obvious deformity (Figure 1). He was unable to abduct his arm above 90 degrees without assistance. He had full passive range of motion. Otherwise, his musculoskeletal and neurologic examination findings were normal, except for 4/5 strength in shoulder abduction.
Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?
A. Amyotrophic lateral sclerosis.
B. Backpack palsy.
C. Hereditary neuropathy.
D. Monomelic amyotrophy.
E. Neuralgic amyotrophy.
REFERENCESshow all references
1. Farrar MA, Park SB, Krishnan AV, Kiernan MC, Lin CS. Axonal dysfunction, dysmyelination, and conduction failure in hereditary neuropathy with liability to pressure palsies. Muscle Nerve. 2014;49(6):858–865....
2. Creemers H, et al. Prognostic factors for the course of functional status of patients with ALS. J Neurol. 2014;262(6):1407–1423.
3. Nylund T, et al. Recovery of brachial plexus lesions resulting from heavy backpack use. BMC Musculoskelet Disord. 2011;12:62.
4. Yoo SD, et al. Monomelic amyotrophy (hirayama disease) with upper motor neuron signs. Ann Rehabil Med. 2015;39(1):122–127.
5. Stutz CM. Neuralgic amyotrophy: Parsonage-Turner syndrome. J Hand Surg Am. 2010;35(10):2104–2106.
This series is coordinated by John E. Delzell, Jr., MD, MSPH, Assistant Medical Editor.
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