What is thoracic outlet syndrome?

Thoracic Outlet Syndrome (TOS)

Thoracic outlet syndrome is a condition characterized by compression of neurovascular structures (nerves, arteries, or veins) as they pass through the thoracic outlet between the clavicle and first rib, causing upper extremity symptoms including pain, numbness, tingling, weakness, swelling, and discoloration. 1

Types of TOS

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

1. Neurogenic TOS (95%): Compression of the brachial plexus
2. Venous TOS (4-5%): Compression of the subclavian vein
3. Arterial TOS (1%): Compression of the subclavian artery 2, 3

Prevalence and Epidemiology

• Estimated prevalence of symptomatic TOS is 10 per 100,000 people 1
• Delayed diagnosis beyond 14 days significantly worsens outcomes 1

Etiology

Multiple factors can contribute to TOS development:

• Congenital abnormalities (cervical ribs, first rib anomalies)
• Anatomical variations in brachial plexus routing
• Hypertrophy of neck musculature
• Trauma or repeated overhead motions
• Postural abnormalities
• Scalene muscle scarring
• Fibrous bands 1, 4, 2

Clinical Presentation

Symptoms vary based on the compressed structure:

Neurogenic TOS

• Upper extremity pain
• Numbness and tingling
• Weakness
• Pain/paresthesias in neck, thorax, shoulder, medial arm, forearm, and fingers 1, 2

Venous TOS

• Arm swelling
• Cyanosis
• Pain due to subclavian vein obstruction 1

Arterial TOS

• Arm claudication
• Coldness
• Pallor
• Decreased pulses 1, 3

Diagnostic Evaluation

Physical Examination

• Assess for diminished radial pulse with provocative maneuvers
• Evaluate for muscle imbalances and postural abnormalities
• A systolic blood pressure difference >25 mmHg between arms indicates potential arterial compression 1

Imaging

• Chest radiography: Identifies osseous abnormalities (cervical ribs, first rib anomalies)
• Duplex ultrasound: Evaluates venous thrombosis and patency; can assess costocervical space with provocative maneuvers
• Catheter venography: Gold standard for diagnosis of venous TOS
• MRI: High-resolution T1 and T2-weighted sequences in neutral and arms-abducted positions
• CT imaging: Confirms residual first rib components contributing to venous compression 1

Treatment Approach

Conservative Management

• First-line approach for most patients, especially neurogenic TOS
• Targeted physical therapy
• Postural correction
• Activity modification
• Anti-inflammatory medications
• Weight loss
• Botulinum toxin injections in select cases 1, 2

Surgical Intervention

Indicated when conservative management fails or in cases of vascular TOS:

• Surgical decompression components:

  • First rib resection
  • Scalenectomy
  • Cervical rib resection (if present)
  • Resection of subclavius muscle and costoclavicular ligament 1

• Approach options:

  • Infraclavicular approach: Provides excellent access to costoclavicular space
  • Transaxillary approach: Allows greater field of view for first rib excision
  • Supraclavicular approach: Favored for scalenotomies 1, 5, 6

Vascular TOS-Specific Treatment

• Catheter-directed thrombolysis to restore venous patency
• Anticoagulation initiated after thrombolysis and maintained until surgical decompression
• Combination of surgical decompression with intraoperative venoplasty has shown 92% primary patency and 96% secondary patency rates 1

Post-Surgical Rehabilitation

• Passive and assisted mobilization of the shoulder starting immediately post-surgery
• Resistance strength training starting at 8 weeks postoperatively
• Interval anticoagulation typically discontinued after successful surgical decompression and rehabilitation 1, 2

Complications of Surgical Treatment

• Injury to subclavian vessels
• Brachial plexus injury
• Hemothorax
• Pneumothorax 2

Outcomes

• With proper patient selection, surgical treatment can provide satisfactory results
• Long-term studies show 82.6% of patients can achieve complete relief of symptoms 6
• Successful treatment allows return to unrestricted upper extremity activity, improving functional status and quality of life 1

Important Considerations

• TOS is not a diagnosis of exclusion - there should be evidence for a physical anomaly that can be corrected
• A multidisciplinary approach involving vascular surgeons, neurologists, and physical therapists yields the best outcomes
• Prompt diagnosis and treatment are essential, as delays beyond 14 days significantly worsen outcomes 1, 2, 6