Updated: 3/10/2019

Thoracic Outlet Syndrome (TOS)

Review Topic
  • A 40-year-old man presents with difficulty grasping his tennis racket. The patient reports difficulty with maintaining a strong grip on his racket. This symptom is accompanied by numbness and tingling. On physical exam, there is atrophy of his intrinsic hand muscles.  
  • Clinical definition
    • syndrome resulting from compression/obstruction of the lower trunk of the brachial plexus and subclavian vessels as it passes through the thoracic outlet 
      • the thoracic outlet is above the first rib and behind the clavicle
      • classified into three types
        • neurogenic (compression of brachial plexus)
        • arterial (obstruction in arteries)
        • venous (obstruction in veins)
  • Epidemiology
    • demographics
      • adults
  • Etiology
    • bony
      • cervical rib
        • an extra rib arising from 7th cervical vertebra
      • rudimentary first rib
    • soft tissue
      • fibrous band from first rib to tip of C7 transverse process
      • hypertrophy of nearby muscles
        • more commonly in weight lifters or athletes
      • Pancoast tumor causing compression
      • cysts
    • trauma
  • Pathogenesis
    • compression of brachial plexus can cause neuropathies
    • compression of subclavian vein or artery can cause edema
  • Symptoms
    • neurogenic
      • difficulty grasping or gripping
      • numbness and tingling in ulnar distribution
      • pain or weakness with elevation or repetitive use of the affected arm
    • arterial
      • claudication
      • diffuse arm and hand pain
      • fatigue and ache, especially after exertion of muscle
    • venous
      • upper extremity swelling
      • diffuse arm or hand pain
  • Physical exam
    • careful neurovascular exam should be performed 
    • neurogenic
      • atrophy of intrinsic hand muscles
      • decreased sensation in ulnar nerve distribution
      • reproducible pain with elevation of arms
    • arterial
      • pallor and cool upper extremities
      • weak or absent radial or ulnar pulse
      • may have decreased blood pressure in the affected arm
    • venous
      • edema
      • cyanosis of upper extremity
      • distended veins
  • Radiographs
    • indication
      • may reveal bony abnormalities
    • findings
      • cervical or rudimentary first rib
      • Pancoast tumor
  • Magnetic resonance imaging (MRI)
    • indication
      • may reveal soft tissue abnormalities
  • Ultrasound
    • indication
      • if vascular TOS is suspected
    • findings
      • vascular compression
  • Angiography
    • indications
      • if vascular TOS is suspected but ultrasound is unrevealing or further clarification is needed
    • findings
      • compression
  • Making the diagnosis
    • most cases are clinically diagnosed
  • Other causes of vascular compromise, such as emboli
    • distinguishing factor
      • pain worsened with exertion of the affected muscle and relieved with rest
  • Conservative
    • physical therapy
      • indication
        • for all patients
  • Medical
    • nonsteroidal anti-inflammatory drugs (NSAIDs)
      • indication
        • pain management
    • anticoagulation       
      • indication
        • patients with suspected thrombosis causing compression
  • Operative
    • surgical decompression
      • indications
        • patients with fibrous band
        • patients with cervical rib
        • pain refractory to conservative management
  • Aneurysm formation (post-stenotic)
  • Thromboembolism

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