• Clinical science

Thoracic outlet syndrome

Abstract

Thoracic outlet syndrome (TOS) is an umbrella term for conditions involving the compression of neurovascular structures (e.g., the brachial plexus or the subclavian artery or vein) as they pass from the lower neck to the armpit. Causes include trauma, tumors, or the presence of a cervical rib. Neurogenic TOS is the most common type and involves the compression of the brachial plexus, leading to neck pain and numbness and tingling in the fingers. Arterial TOS involves compression of the subclavian artery and presents with pain, pallor, coldness, and pulselessness in the affected arm, especially during overhead activities. Venous TOS results in pain, cyanosis, and swelling of the arm. Imaging techniques such as duplex sonography, X-ray, MRI, or electrodiagnostic testing are used to detect the cause of TOS. Mild symptoms should be treated with pain medication and physical therapy. Surgical resection of the causal structures might become necessary in the case of progressive neurologic dysfunction or acute vascular insufficiency.

Etiology

  • Compression of subclavian vessels and the lower trunk
    • Physical trauma (e.g. hyperextension neck injuries)
    • Repetitive motion of the abducted and externally rotated shoulder; (e.g. tennis; , baseball; , swimming, repetitive throwing, carrying heavy objects overhead)
    • Structural abnormalities

References:[1][2][3]

Clinical features

  • Clinical features of TOS depend on the anatomic structure affected by compression; and are more pronounced during and after overhead activity.
  • Compression of the subclavian artery
    • Mild arm ache and fatigue
    • Pulselessness, pain, pallor, paresthesia and coldness in the affected arm (5 Ps)
    • ↓ Blood pressure of > 20 mm Hg in the affected arm compared with the contralateral arm
  • Compression of the subclavian vein
  • Compression of parts of the brachial plexus
  • Provocation tests
    • Adson Test (thoracic outlet test)
      • Execution
        • The patient sits in a relaxed position while the examiner palpates the radial pulse.
        • Passive abduction of 90°; lateral rotation and extension of the arm
      • Interpretation
        • Positive Adson test: reduced or absent pulse or paresthesia → sign of TOS
        • Negative Adson test: no change in pulse or sensation
    • Wright test New anchor 11820
      • Execution: The examiner progressively hyperabducts and externally rotates the affected arm while assessing the ipsilateral radial pulse.
      • Interpretation
        • Positive: reduced or absent pulse or paresthesia
        • Negative: no change in pulse or sensation
    • Roos stress test
      • Execution: Both shoulders are positioned in abduction and are externally rotated at 90° angles, with elbows flexed at 90°, while the patient repeatedly makes a fist and then relaxes the hand.
      • Interpretation
        • Positive: sensation of heaviness or fatigue in affected limb
        • Negative: no change in sensation

Swelling and venous distention in the arm may be a sign of venous thrombosis of the arm!
References:[1]

Diagnostics

  • Radiographs of the spine, shoulder, collarbone → bony abnormalities
  • CT or MRI imaging mainly to exclude other conditions that present similarly .
  • Other tests depend on suspected underlying pathology
    • Arterial ; TOS → MR angiography
    • Venous; TOS → duplex ultrasonography
    • Neurogenic; TOS → electromyography/nerve conduction studies

References:[1]

Treatment

  • In mild cases: physical therapy; , weight reduction, NSAIDs, thrombolytics with continued anticoagulation in the case of venous thrombosis
  • In cases of acute vascular insufficiency or progressive neurologic dysfunction, or if conservative treatment fails: thoracic outlet decompression surgery
    • Transaxillary resection of the cervical rib or first rib
    • Angioplasty or venous or arterial bypass for severely narrowed vessels

References:[1]