Thoracic Outlet Syndrome

Key Features

Essentials of Diagnosis

• Compression of neurovascular structures supplying upper extremity

• Predominant symptoms depend on whether the compression chiefly affects neural or vascular structures

General Considerations

• Intermittent or continuous pressure on elements of the brachial plexus (> 90% of cases) and the subclavian or axillary vessels by anatomic structures of the shoulder girdle region results in symptoms and signs

• The neurovascular bundle can be compressed between the anterior or middle scalene muscles and a normal first thoracic rib or a cervical rib

• Predisposing factors

  • Scarred scalene neck muscle secondary to neck trauma

  • Sagging of the shoulder girdle, resulting from aging, obesity, or pendulous breasts

  • Faulty posture

  • Occupation

  • Thoracic muscle hypertrophy from physical activity (eg, weight-lifting, baseball pitching)

Clinical Findings

Symptoms and Signs

• Some combination of four symptoms involving the upper extremity: pain, numbness, weakness, and swelling

• Onset usually gradual but can be sudden

• Pain radiating from the point of compression to the base of the neck, axilla, shoulder girdle region, arm, forearm, and hand

• Numbness and paresthesias, distributed to the volar aspect of the fourth and fifth digits

• Weakness and muscle atrophy

• Reflexes not usually altered

• Swelling

• Some patients spontaneously notice aggravation of symptoms with specific positioning of the arm, at night, or upon prolonged use of the extremities

• Vascular symptoms consist of arterial ischemia, characterized by

  • Pallor of fingers on elevation of extremity

  • Sensitivity to cold

  • Gangrene of digits (rare)

  • Venous obstruction marked by edema, cyanosis, and engorgement (also rare)

• Symptoms can be provoked within 60 seconds over 90% of the time by having a patient elevate the arms in a "stick-em-up" position (ie, abducted 90 degrees in external rotation)

• Obliteration of the radial pulse with certain maneuvers of the arm or neck, once considered a highly sensitive sign of thoracic outlet obstruction, does not occur in most cases

Differential Diagnosis

• Osteoarthritis of cervical spine

• Tumors of the superior pulmonary sulcus, cervical spinal cord, or nerve roots

• Periarthritis of the shoulder

Diagnosis

Imaging Studies

• Chest radiography identifies presence of cervical rib

• MRI with arms held in different positions useful in identifying sites of impaired blood flow

• Angiography confirms intra-arterial or venous obstruction

Diagnostic Procedures

• Conduction velocities of the ulnar and other upper extremity peripheral nerves may help localize the site of compression

Treatment

Surgery

• Required by < 5% of patients

• More likely to relieve neurologic rather than vascular component that causes symptoms

Therapeutic Procedures

• Conservative measures (eg, physical therapy) to relieve compression ...