Case reports: unusual cause of shoulder pain in a collegiate baseball player.

The objective of reporting this case was to introduce a unique cause of shoulder pain in a high-level Division I NCAA collegiate baseball player. Various neurovascular causes of shoulder pain have been described in the overhead athlete, including quadrilateral space syndrome, thoracic outlet syndrome, effort thrombosis, and suprascapular nerve entrapment. All of these syndromes are uncommon and frequently are missed as a result of their rarity and the need for specialized tests to confirm the diagnosis. This pitcher presented with nonspecific posterior shoulder pain that was so severe he could not throw more than 50 feet. Eventually, intermittent axillary artery compression with the arm in abduction resulting from hypertrophy of the pectoralis minor and scalene muscles was documented by performing arteriography with the arm in 120 degrees abduction. MRI-MR angiographic evaluation revealed no anatomic abnormalities. The patient was treated successfully with a nonoperative rehabilitation program and after 6 months was able to successfully compete at the same level without pain.