Thoracic Outlet Syndrome

Other Names

• Neurogenic thoracic outlet syndrome
• Arterial thoracic outlet syndrome
• Venous thoracic outlet syndrome
• Vascular thoracic outlet syndrome

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Background

• Disorder that results in compression of neurovascular bundle exiting the thoracic outlet
  • thoracic outlet is an area of the neck defined as a space between the clavicle and first rib
  • Contains the brachial plexus, subclavian artery and subclavian vein
  • Compression causes symptoms that include upper extremity pallor, paresthesia, weakness, muscle atrophy and pain

Epidemiology

• Incidence difficult to discern with articles reporting incidence from 3-80/1000
• Neurogenic thoracic outlet account for around 90% of cases
• Another study estimates 95% neurogenic, 4% venous and 1% arterial

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Pathophysiology

• Usually grouped into congenital, traumatic or functionally acquired
  • Congenital - Presence of cervical rib, anomalous first rib, elongated transverse process
    • Muscular anomalies (scalenus anticus anomolies)
    • Fibrous anomalies (transversocostal, costocostal, etc.) are most common
  • Traumatic - whip-lash injuries and falls
    • Does not have to happen acutely and can progress over time after old injury
  • Functional acquired related to vigorous or repetitive activity related to sports or work
    • Typically overhead athletes or occupations with head or shoulders flexed anteriorly such as secretaries, computer operators, etc.

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Risk Factors

• Females more likely than males to be diagnosed with TOS
• Most common ages diagnosed are between ages 20-50

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Differential Diagnosis

• Other brachial plexus injury
  • Brachial neuritis, Pancoast syndrome, radiation induced plexopathy, Parsonage-Turner syndrome
• Cervical pain
• Tunnel syndromes (carpal, cubital, radial)
• Degenerative disease of glenohumeral joint, acromioclavicular joint, cervical spine
• Non-compressive and peripheral neurologic disease

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Clinical Features

• History
  • Patients typically report (needs to be updated)
• Physical Exam: Physical Exam Neck
  • Need to examine entire cervical spine and upper extremity
  • Inspect head and neck posture, looking for muscle atrophy
  • Observe skin color, temperature, hair distribution
  • Blood pressure can differ between arms
  • Shoulder and chest may have edema, pallor, visible collateral veins, bluish discoloration
  • Arterial TOS can have supraclavicular fullness or anuerismal pulsations
  • Motor strength of digits 1-3 is typically preserved
• Slemonosky triad
  • Tenderness in the supraclavicular area
  • Weakness of the 4th and 5th digits
  • Hand paleness and/or paresthesias with elevation of the hands
• Special Tests
  • Adson test
  • Costoclavicular Test
  • Wrights Test
  • Elevated Arm Stress Test
  • Cyriax Release Test
  • Halstead Test

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Evaluation

Radiographs

• Standard Cervical Spine Radiographs
• Evaluate for
  • Cervical first rib
  • Prominent ribs or transverse processes
  • Fracture calluses
  • Compressive tumors

Ultrasound

• Ultrasound maintains high sensitivity and specificity and is noninvasive and inexpensive (need citation)
  • Can also assess dynamic blood flow during compression maneuvers such as hyperabduction

MRI

• Should be obtained on cervical spine or brachial plexus for neurogenic TOS
  • Indications: usually profound weakness, failure to improve with conservative management

EMG/NCS

• Nerve conduction studies sometimes performed and are frequently normal

Other

• Prior gold standard arteriography and venography for vascular TOS (catheter-based)
  • Uncommonly used in modern medicine
• Injection into the scalenes rarely used but can be helpful for diagnostic purposes in some cases

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Classification

• Neurogenic thoracic outlet syndrome
• Venous thoracic outlet syndrome
• Arterial thoracic outlet syndrome

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Management

• Depends on classification
  • Neurogenic TOS
  • Most cases treated initially with conservative management, although appropriate regimen controversial
    • Multimodal approach with patient education (postural mechanics, weight control, relaxation techniques), TOS-specific rehabilitation (active stretching, targeted muscle strengthening, activity modification) and pharmacologic therapy
    • Pharmacologic management often provides symptomatic relief
      • NSAIDs and oral steroids used for neuropathic pain
      • Muscle relaxants, anticonvulsants and antidepressants occasionally used as adjuvants
      • Injection of local anesthetic, steroids or botulism toxin into anterior scalene/pectoralis have been used
  • Cases that fail conservative management for 4-6 months may be candidate for surgery if there is uncontrolled pain or progressive upper extremity weakness
    • Surgery of choice is first rib resection to decompress brachial plexus and can be performed by vascular surgeons (mostly), neurosurgeons, orthopedic surgeons and plastic surgeons.
    • Transaxillary, supraclavicular, and infraclavicular approaches used, with each having positive results with no definitively superior technique
    • Scalenectomy and debridement of any fibrous bands often done depending on anatomy and symptoms

• • Venous TOS
    • Acute (<6 weeks) treated with anticoagulation, thrombolysis (catheter-directed), decompression by first rib removal and or/scalenectomy and venoplasty
    • Anticoagulation normally given for additional 3-6 months until venous patency confirmed with follow up imaging
      • Reports greater than 90 percent clinical success and less invasive methods such as robotic and thoracoscopic assisted techniques becoming more popular
    • Chronic (> 6 weeks) with evidence of stenosis or occlusion treated with surgical decompression with first rib removal and or/scalenectomy
      • Thombolysis may be performed with total occlusion
      • Venoplasty can be used for residual subclavian stenosis
    • Intermittent without evidence of obstruction or occlusion may have trial of conservative management including limiting provocative position
      • Many have surgical decompression without anticoagulation or venoplasty
  • Arterial TOS
    • Approached in similar manner and dependent on severity of complications
      • Asymptomatic patients without evidence of arterial degeneration may be managed nonsurgically with serial arterial ultrasound every 6 months
        • No definitive guidelines exist
      • Surgical treatment when there is evidence of arterial complications such as intimal damage, mural thrombus, embolization, post-stenotic first rib or aneurysmal formation
      • Decompression with resection of cervical or first ribs, fibrous bands, scalenectomy and any other associated anomalies
        • Debate whether scalenectomy alone is as effective as first rib resection
      • Next step is arterial resection of the source of arterial embolus such as subclavian artery aneurysm or luminal stenosis
      • Digital revasculatization is the last step with vascular reconstruction in the form of primary anastomosis, interposition graft or axillary-brachial bypass to improve outflow of the limb

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Complications

• Pneumothorax, wound infection, hematoma and hemothorax
• Potential for arterial, venous or nerve root injuries (rare)

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