Answer
C: Neurogenic thoracic outlet syndrome
Educational Objective
Diagnose neurogenic thoracic outlet syndrome.
Critique
This patient probably has neurogenic thoracic outlet syndrome (nTOS) (Option C). nTOS is caused by compression of the nerve roots of the brachial plexus in the interscalene triangle of the neck (bordered by the anterior and middle scalene muscles and the first rib). Young, thin, active women with repetitive overhead stress to an upper extremity are most likely to experience nTOS, which typically presents with nonradicular and anatomically widespread symptoms (numbness, paresthesia, and pain) affecting the arm, neck, and shoulder. Atrophic weakness of hand and arm muscles can occur but is typically a late manifestation. Neck rotation, head tilting, arm abduction, and arm external rotation may provoke symptoms in some patients. Electrodiagnostic studies are frequently normal, and imaging may reveal an anomalous cervical rib, which predisposes to this condition. First-line therapy for nTOS includes physical therapy focusing on improving posture and strengthening the shoulder girdle muscles.
Arterial TOS (aTOS) (Option A) is caused by subclavian artery compression, with or without thrombosis; it usually occurs in the presence of an anomalous cervical rib. Symptoms include arm or hand pain (which may be exertional), weakness, paresthesia, coolness, and pallor. Some patients may have blood pressure discrepancies between the arms or diminished pulses in the affected extremity. On occasion, a bruit may be auscultated over the ipsilateral subclavian artery. This patient has no evidence of the arterial insufficiency that is characteristic of aTOS.
Cervical radiculopathy (Option B) often presents with constant neck and shoulder pain in a radicular distribution. The pain is aggravated by the position of the neck. The wide anatomic distribution and nonradicular nature of this patient's symptoms make cervical nerve root compression less likely.
Venous TOS (vTOS) (Option D) is caused by compression of the subclavian vein within the costoclavicular junction where it passes anterior to the anterior scalene muscle. vTOS is characterized by substantial upper extremity swelling as well as pain in the upper extremity, chest, and shoulder. Cyanosis may be present. vTOS is most common in young, active men and often affects the dominant upper extremity. The absence of swelling or cyanosis and the presence of paresthesia make vTOS unlikely in this patient.
Key Point
Neurogenic thoracic outlet syndrome typically presents with nonradicular and anatomically widespread symptoms (weakness, numbness, paresthesia, and pain) affecting the arm, neck, and shoulder; symptoms worsen with repetitive overhead activities.
Bibliography
Kuhn JE, Lebus V GF, Bible JE. Thoracic outlet syndrome. J Am Acad Orthop Surg. 2015;23:222-32. [PMID: 25808686] doi:10.5435/JAAOS-D-13-00215
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