What is the recommended evaluation and treatment approach for Thoracic Outlet Syndrome (TOS)?

Evaluation and Treatment Approach for Thoracic Outlet Syndrome (TOS)

The recommended evaluation for Thoracic Outlet Syndrome (TOS) should begin with chest radiography followed by ultrasound duplex Doppler, with MRI reserved for cases requiring further evaluation of the brachial plexus and soft tissues. 1

Classification and Initial Diagnosis

TOS can be classified into three main types based on the compressed structures:

1. Neurogenic TOS (NTOS) - Most common (82% of referrals), involving brachial plexus compression 2
2. Venous TOS (VTOS) - 16% of referrals, involving subclavian vein compression 2
3. Arterial TOS (ATOS) - Least common (2% of referrals), involving subclavian artery compression 2

Initial Diagnostic Workup

• Chest radiography: First-line imaging to identify:

  • Osseous abnormalities (cervical ribs, first rib anomalies)
  • Previous surgical changes
  • Lung masses
  • Should be performed upright as malalignment can be underrepresented on supine radiography 1

• Bilateral arm blood pressure measurement:

  • A systolic blood pressure difference >25 mmHg between arms is significant
  • This finding doubles prevalence and independently predicts mortality 1

• Physical examination maneuvers:

  • Adson's Test, Wright's Test, and Eden's Test to check for diminished radial pulse
  • Note: The American College of Radiology warns against relying on a single test maneuver due to insufficient sensitivity/specificity 1

Advanced Imaging

For Suspected Neurogenic TOS:

• MRI of the chest without contrast:

  • Superior for evaluating brachial plexus and cervical spine
  • Can identify brachial plexus compression, cervical spine pathology, and soft tissue masses
  • Dynamic evaluation of neurovascular bundles in the costoclavicular, interscalene, and pectoralis minor spaces 3
  • Noncontrast MRI is usually sufficient for diagnosis 3

• Diagnostic injection technique:

  • Ultrasound-guided anterior scalene muscle injection with local anesthetic
  • Confirms diagnosis if symptoms are relieved following injection
  • Helps predict likelihood of success with surgical intervention 1

For Suspected Vascular TOS:

• Ultrasound duplex Doppler:

  • Evaluates subclavian artery and vein compression
  • Measures changes in vessel diameter and peak velocity during arm abduction
  • Assesses lymph nodes in the neck and axilla 1

• CT with IV contrast:

  • Recommended if vascular complications are suspected
  • More cost-effective than MRA/MRV
  • Can evaluate for thrombosis or stenosis 1

Treatment Approach

Conservative Management (First-Line)

• Physical therapy and postural correction:
  • Initial treatment for all types of TOS 1
  • Includes anti-inflammatory medication, weight loss, strengthening exercises 4
  • Botulinum toxin injections may be considered 4

Surgical Intervention

Indicated for:

• Cases with significant anatomical abnormalities
• Vascular TOS with complications
• Neurogenic TOS with progressive neurological deficits 1

Surgical options include:

• First rib resection
• Scalenectomy
• Cervical rib resection
• Vascular reconstruction 1

Approach Selection:

• Transaxillary approach: Preferred for first rib excision to relieve compressed vessels
• Supraclavicular approach: Favored for scalenotomies when the anterior scalene muscle impinges on surrounding structures
• Combined approach: When a larger field of view is required 5

Post-Surgical Care

• Begin passive/assisted mobilization of the shoulder immediately postoperatively
• By 8 weeks, patients can begin resistance strength training 4
• Post-surgical rehabilitation is critical for long-term success 1

Special Considerations

For Venous TOS (VTOS)

• Usually requires urgent thrombolysis and anticoagulation in addition to surgical decompression 6

For Arterial TOS (ATOS)

• Treatment focuses on restoring arterial blood flow in addition to surgical decompression 6
• Endovascular revascularization may be considered over surgery due to lower complication rates 1
• Routine revascularization in asymptomatic patients with atherosclerotic subclavian artery disease is not recommended 1

Potential Complications of Surgical Treatment

• Injury to subclavian vessels potentially leading to exsanguination
• Brachial plexus injury
• Hemothorax
• Pneumothorax 4

Pitfalls to Avoid

• Overdiagnosis: Positive imaging findings without symptoms can occur, as compression during provocative positioning can be seen in asymptomatic individuals 1
• Misdiagnosis: TOS is not a diagnosis of exclusion - there should be evidence for a physical anomaly that can be corrected 4
• Incomplete evaluation: Relying on a single diagnostic test rather than a comprehensive approach 1