Thoracic Outlet Syndrome

Key Features

Essentials of Diagnosis

• Compression of neurovascular structures supplying upper extremity

General Considerations

• Intermittent or continuous pressure on elements of the brachial plexus 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)

• Predominant symptoms depend on whether obstruction affects neural or vascular structures

Clinical Findings

Symptoms and Signs

• Onset usually gradual but can be sudden

• Pain

• Numbness

• Weakness

• Swelling

• 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)

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

• Reflexes not usually altered

• 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

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 of neurovascular bundle

Outcome

Complications

• Gangrene of the digits or venous obstruction if there is vascular obstruction

Prognosis

• Greater than 95% of patients can be treated successfully with conservative therapy, consisting of physical therapy and avoiding postures or activities that compress the neurovascular bundle

Prevention

• Avoid faulty posture or physical activities (eg, weight-lifting, baseball pitching) that compress neurovascular bundle

When to Refer