Trekker's Shoulder

To the Editor: Upper-trunk injuries of the brachial plexus are rare in adults. We report a hitherto unrecorded cause of Erb's palsy.A 26-year-old male backpacker reported weakness in his right arm after a trek in the mountains. The weakness started soon after he began a moderately steep descent, wearing a heavily laden, loosely slung backpack, and it became progressively worse by evening. He had paresthesia in the arm and was unable to lift it without support. Examination revealed Grade II to III power in the abductors and flexors of the affected shoulder, the flexors of the elbow, and the . . .