thoracic outlet syndrome

Introduction

Symptoms produced by obstruction of the neurovascular bundle (subclavian artery, subclavian vein, lower trunk of the brachial plexus) as it enters the axilla.

Etiology

• true neurogenic thoracic outlet syndrome
  • compression of the lower trunk of the brachial plexus by an anomalous band of connective tissue connecting an elongated transverse process of C7 with the 1st rib
• arterial thoracic outlet syndrome
  • aneurysm of the subclavian artery
  • compression of the subclavian artery:
    • anomalous cervical rib
    • tumor (especially Pancoast tumor)
• venous thoracic outlet syndrome
  • compression of the subclavian vein within the costoclavicular junction as it passes anterior to the anterior scalene muscle
  • most common in young, active men affecting dominant upper extremity
• sagging musculature related to aging, obesity, or heavy breasts

Clinical manifestations

• pain & paresthesias when using the arms, especially when working in certain positions, especially overhead
• pain in & around in shoulders, in the supraclavicular region or between the shoulders
• may be palpable abnormality above the clavicle
• signs referable to the lower part of the brachial plexus
  • weakness of the intrinsic muscles of the hand (late manifestation)
  • diminished sensation on the palmar aspect of the 4th & 5th digits
• unilateral Raynaud's phenomenon
• trophic changes in the fingers
• sensory loss over the ulnar side of the hand
• interosseous atrophy may be present
• sensation of swelling in the arms
• forearm & hand pain
• no dizziness
• arterial arterial thoracic outlet syndrome
  • Adson's sign
  • coolness, pallor
  • arm or hand may be exertional
  • brachial blood pressure differences between arms
  • bruit may be heard over affected subclavian artery
• venous thoracic outlet syndrome
  • upper extremity edema
  • upper extremity pain, shoulder pain, chest pain
  • cyanosis may be present

Laboratory

• complete blood count
• erythrocyte sedimentation rate
• general chemistries
  • serum Ca+2, serum albumin
• thyroid function testing
• antinuclear antibodies
• rheumatoid factor

Diagnostic procedures

• electromyography is helpful
• nerve conduction studies are helpful

Radiology

• chest X-ray
• cervical spine films may show cervical rib or elongated transverse process of C7
• aortic arch arteriogram
• venogram
• ultrasound
• magnetic resonance imaging, magnetic resonance angiography

Differential diagnosis

• Pancoast tumor
• subclavian steal
• impingement of a cervical nerve (cervical radiculopathy)
• cervical cord tumor
• brachial plexus paralysis
• carpal tunnel syndrome
• hypothyroidism
• peripheral neuropathy
• syringomyelia
• progressive muscle atrophy
• reflex sympathetic dystrophy
• thrombophlebitis
• upper extremity peripheral arterial disease
• giant cell arteritis
  • elevated ESR, transient monocular vision loss, fatigue
  • new-onset arm claudication
  • symptoms of polymyalgia rheumatica

Management

• conservative management
  • unless pain severe or critical features
  • physical therapy
    • exercises to strengthen muscles around thoracic outlet
  • occupational therapy
    • ergonomics of proper sitting, work, sleeping positions
• surgery
  • < 5% of patients require surgical treatment
  • indications:
    • muscle wasting
    • persistent sensory loss,
    • unacceptable pain
    • progressive arterial or venous insufficiency
  • excellent outcomes after surgical intervention

More general terms

• plexopathy
• syndrome

More specific terms

• cervical rib syndrome
• scalenus anticus syndrome

Additional terms

• Adson's sign (test)
• Pancoast tumor (superior pulmonary sulcus tumor)
• superior vena cava (SVC) syndrome

Patient information

thoracic outlet syndrome patient information