What are the presentation, diagnostic tests, and treatment options for thoracic outlet syndrome?

Thoracic Outlet Syndrome: Presentation, Diagnostic Tests, and Treatment

Thoracic outlet syndrome (TOS) is characterized by compression of neurovascular structures at the thoracic outlet, presenting with three distinct variants: neurogenic TOS (95%), venous TOS (4-5%), and arterial TOS (1%), each with characteristic symptoms based on the compressed structure. 1, 2

Clinical Presentation

• Neurogenic TOS presents with arm pain, paresthesias, weakness, and wasting of intrinsic hand muscles due to brachial plexus compression 2, 3
• Venous TOS presents with arm swelling, heaviness, cyanosis, and visible collateral veins due to subclavian vein compression 4, 5
• Arterial TOS presents with digital ischemia, pallor, coldness, and pain due to subclavian artery compression 4, 5
• Symptoms typically worsen with arm elevation or abduction, and patients may report occupational or repetitive stress triggers 2, 6

Anatomical Considerations

• Compression can occur in three distinct spaces: the interscalene triangle, costoclavicular triangle, and subcoracoid space 4, 7
• Common anatomical factors include cervical ribs, fibrous bands, anomalous scalene muscle insertions, and post-traumatic scarring 2, 7

Diagnostic Tests

Initial Evaluation

• Chest radiography is recommended as the first-line imaging test to identify osseous abnormalities such as cervical ribs or first rib anomalies 8, 4
• Provocative physical examination maneuvers (Adson's test, elevated arm stress test, costoclavicular maneuver) should be performed, though these have limited specificity 2, 6

Specific Tests by TOS Type

For Neurogenic TOS:

• MRI of the brachial plexus without and with IV contrast is recommended to evaluate for nerve compression 4
• Electromyography and nerve conduction studies help identify nerve compression patterns, though may be normal in early stages 3, 7

For Venous TOS:

• Duplex ultrasound is the first-line imaging test, performed in both neutral position and with provocative maneuvers 8, 9
• Catheter venography is the gold standard for definitive diagnosis when intervention is being considered 8
• CT venography or MR venography should be performed in neutral and elevated arm positions to evaluate for venous compression, thrombosis, and collateral circulation 8, 9

For Arterial TOS:

• CTA with IV contrast, MRA, or ultrasound duplex Doppler is recommended 4
• Imaging should be performed in both neutral and stressed positions to identify arterial compression, aneurysm, or thrombosis 8, 4

Treatment Options

Conservative Management

• First-line therapy includes physical therapy, NSAIDs, lifestyle modifications, and ergonomic adjustments 2, 6
• Botulinum toxin injections into the scalene muscles may provide temporary relief for neurogenic TOS 2, 6
• Conservative treatment should typically be attempted for 3-6 months before considering surgical intervention 4

Surgical Management

• Surgical decompression is indicated when conservative management fails or in cases of progressive symptoms, significant functional compromise, or vascular complications 4
• Common surgical approaches include:
  • Supraclavicular approach - preferred for scalenectomy and neurogenic TOS 3, 5
  • Transaxillary approach - provides better visualization for first rib resection 3, 5
  • Combined approaches may be necessary in complex cases 3
• For venous TOS with thrombosis, thrombolysis followed by surgical decompression is typically required 5
• For arterial TOS, subclavian artery reconstruction is often necessary in addition to decompression 5

Diagnostic Pitfalls

• Venous compression during arm abduction is common in asymptomatic individuals (71% in one study), so imaging findings must be correlated with clinical symptoms 8
• TOS is not a diagnosis of exclusion; there should be evidence of a physical anomaly that can be corrected 2
• Other conditions with similar presentations (cervical radiculopathy, peripheral nerve entrapment) must be ruled out 6, 7