THORACIC OUTLET SYNDROME
The Great Imitator
Clinical Types
Critical Must-Knows
- Neurogenic TOS usually affects the Lower Trunk (C8/T1) - Ulnar border symptoms.
- The most common compression site is the Interscalene Triangle.
- Venous TOS is a DVT of the Subclavian Vein (Paget-Schroetter Syndrome).
- Arterial TOS is almost always associated with a bony anomaly (Cervical Rib).
- Roos Test (EAST) is the most sensitive screening test.
- Adson's Test obliterates the radial pulse (but is positive in many normal people).
Examiner's Pearls
- "Gilliatt-Sumner Hand: severe wasting of Thenar AND Hypothenar muscles (Lower trunk).
- "In Ulnar nerve compression, Thenar is spared. In TOS, Thenar is wasted (C8/T1).
- "First Rib Resection is the definitive surgical treatment.
Clinical Imaging
Imaging Gallery
The Trap: Double Crush
The Diagnosis
Cervical Radiculopathy NTOS symptoms overlap with C8/T1 radiculopathy and Cubital Tunnel Syndrome. Always check the neck (Spurling's test) and the elbow (Tinel's). TOS is a diagnosis of exclusion.
The Test
APB Wasting Look at the Abductor Pollicis Brevis (APB). Carpal Tunnel affects APB. Cubital Tunnel spares APB. TOS (Lower Trunk) affects APB (T1 fibers). TOS = Wasted APB + Wasted Interossei.
| Feature | Neurogenic (NTOS) | Venous (VTOS) | Arterial (ATOS) |
|---|---|---|---|
| Symptom | Pain, Paresthesia | Swelling, Cyanosis | Pallor, Claudication |
| Nerve/Vessel | Brachial Plexus (Lower) | Subclavian Vein | Subclavian Artery |
| Cause | Scalene Hypertrophy/Scar | Repetitive Overhead (Effort) | Cervical Rib |
| Test | Roos, Elvey | Ultrasound/Venogram | Loss of Pulse, Angio |
SIPSpaces of Compression
Memory Hook:Take a SIP of air (Thorax).
LOAF-IGilliatt Sumner
Memory Hook:Lower trunk hits everything in the hand.
EASTRoos Test
Memory Hook:Hands up facing EAST.
Overview
Thoracic Outlet Syndrome (TOS) is a spectrum of disorders caused by compression of the neurovascular bundle (Brachial Plexus, Subclavian Artery, Subclavian Vein) as it exits the thoracic aperture to enter the axilla.
The compression typically occurs at three anatomical narrows: the Interscalene Triangle, the Costoclavicular Space, and the Retro-pectoralis Minor Space.
Pathophysiology and Mechanisms
1. Interscalene Triangle
- Borders: Anterior Scalene (Anterior), Middle Scalene (Posterior), First Rib (Inferior).
- Contents: Brachial Plexus (Trunks) and Subclavian Artery.
- Note: The Subclavian Vein passes ANTERIOR to the Anterior Scalene (outside the triangle). Thus, scalene hypertrophy affects Artery/Nerve but spares Vein.
The C8/T1 roots are most vulnerable at the base of the triangle.
Classification Systems
Neurogenic TOS (NTOS)
- Prevalence: Greater than 95% of cases.
- Demographics: Women > Men (3:1), age 20-50.
- Pathology: Scarring of scalenes, whiplash, repetitive stress.
- Symptoms: Pain in neck/trapezius/arm. Paresthesia in C8/T1 distribution (Ulnar forearm/hand). Weakness (late).
The diagnosis is often clinical, supported by exclusion of other causes.
Clinical Assessment
History
History
- Pain: "Toothache" in the trapezius/neck.
- Activities: Worse with overhead activity (brushing hair, hanging clothes).
- Night: Pain at night (sleeping with arms up).
- Neurological: Numbness in 4th/5th digits (C8).
Ask about trauma (whiplash) which scars the scalenes.
Provocative Tests
Provocative Tests
- Roos Test (EAST): Elevated Arm Stress Test. "Hands up, open/close fists for 3 mins." Positive if pain/heaviness/numbness forces arms down. (Most reliable).
- Adson's Test: Head turned TO side + Deep breath + Extension. Positive if pulse disappears AND symptoms reproduced. (Low specificity).
- Wright's Test: Hyperabduction. Pulse disappears. (Implicates Pec Minor).
- Elvey's Test (ULTT): Upper Limb Tension Test.
Most tests have high false positive rates.
Inspection
Inspection
- Posture: Drooped shoulders?
- Hand: Gilliatt-Sumner Hand (Severe ATOS/NTOS). Wasting of Thenar AND Hypothenar.
- Supraclavicular: Fullness? (Cervical rib or mass).
Cyanosis suggests Venous TOS.
Imaging and Electrodiagnostics
Plain Films
- Cervical Spine: Look for Cervical Rib (C7 transverse process > Transverse process of T1).
- Chest: Anomalous first rib? Clavicle malunion? apical lung tumor (Pancoast)?
Look for elongated C7 transverse processes.
Management Algorithm
Neurogenic TOS
- First Line: Conservative.
- PT: Postural correction, strengthening trapezius (elevate shoulder girdle), stretching scalenes/pec minor.
- Meds: Gabapentin, NSAIDs.
- Botox: Injection into Anterior Scalene (Diagnostic and Therapeutic).
- Surgery: If conservative fails (greater than 6 months). First Rib Resection + Scalenectomy.
Surgery is reserved for refractory cases with significant disability.
Surgical Technique
Approaches
- Transaxillary: Most common. Cosmetically superior. "Roos Approach". Access to 1st rib. Hard to see C-rib or reconstruct vessels.
- Supraclavicular: Best for Nerve visualization and Cervical Rib. Standard for NTOS/ATOS.
- Infraclavicular: Good for Venous (Vein exposure).
Robotic First Rib Resection is emerging.
Complications
Intraoperative Complications
- Pneumothorax: Pleura is attached to the undersurface of the 1st rib via Sibson's fascia (15-30% risk). Chest X-ray in recovery is mandatory.
- Vascular Injury: Subclavian artery or vein laceration - requires immediate vascular repair.
- Brachial Plexus Injury: Direct trauma or excessive traction during first rib resection.
- Phrenic Nerve Palsy: Lies on anterior scalene - must protect during scalenectomy. Results in diaphragm paralysis.
- Long Thoracic Nerve: Injury causes scapular winging - avoid excessive retraction.
- Thoracic Duct Injury: Chylothorax (left-sided approach) - requires drainage and dietary modification.
Careful anatomical dissection and nerve identification prevents most complications.
Rehabilitation
- Monitoring: Chest X-ray in recovery to exclude pneumothorax.
- Protection: Arm sling for comfort (not immobilization).
- ROM: Gentle active-assisted range of motion - avoid overhead activity.
- Activity: No lifting greater than 1kg, avoid driving.
- Wound Care: Keep incision clean and dry, sutures out at 10-14 days.
Pain control with simple analgesia - avoid opioids long-term.
- ROM: Progressive active ROM in all planes.
- PT Focus: Postural correction, scapular setting, cervical stretches.
- Strengthening: Isometric exercises for shoulder girdle.
- Activity: Light activities of daily living, no repetitive overhead work.
- Driving: May resume at 3-4 weeks if comfortable.
Continue physiotherapy addressing underlying postural issues.
- PT Focus: Scapular stabilization, trapezius strengthening, pectoralis stretching.
- Progressive Loading: Gradual increase in resistance exercises.
- Work: Gradual return to desk work, avoid heavy manual labor.
- Sports: No contact sports or heavy lifting yet.
- Nerve Recovery: May take several months for complete sensory recovery.
Address any ergonomic factors at workplace.
- Full Activity: Unrestricted activity by 3 months if symptoms resolved.
- Sports: Gradual return to sports including overhead activities.
- Work: Full duties including manual labor.
- Maintenance: Continue postural exercises long-term to prevent recurrence.
- Review: Final assessment at 3-6 months post-surgery.
Some patients may require ongoing physiotherapy if postural issues persist.
Prognosis
Surgical Outcomes by Type
- NTOS: 80-90% good outcomes if diagnosis is correct and confirmed by positive scalene block response. Poorer results in "Disputed" TOS or workers' compensation cases.
- VTOS: Excellent outcomes with early thrombolysis and first rib resection. Greater than 90% long-term vein patency if treated within 2 weeks.
- ATOS: Good outcomes if arterial reconstruction is patent and no embolic sequelae. May require staged procedures.
Conservative management for NTOS achieves 50-70% improvement with dedicated physiotherapy.
Evidence Base
Roos Test Sensitivity
- Described the Elevated Arm Stress Test (EAST)
- Most reliable screening test for TOS
- Symptoms must be reproduced within 3 minutes
- Pain alone is not positive; must be 'giving way' or paresthesia
Venous TOS Protocol
- Established the standard for Paget-Schroetter
- Thrombolysis first
- First Rib Resection improves patency
- Anticoagulation alone has high recurrence rate
Supraclavicular vs Transaxillary
- Comparison of approaches
- Supraclavicular allows better neurolysis and cervical rib excision
- Transaxillary better cosmesis
- No difference in complication rates
Botox Injection
- Botulinum toxin A into Anterior Scalene
- Significant pain reduction in NTOS
- Positive response predicts surgical success
- Can be used as a diagnostic block
Gilliatt-Sumner Hand
- Classic description of wasted hand in Cervical Rib
- Thenar AND Hypothenar wasting
- Due to lower trunk (C8/T1) compression affecting all intrinsics
- Sensory loss in ulnar forearm (T1)
Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: The Swollen Arm
"A 22-year-old male weightlifter presents with specific, blue, swollen right arm after a gym session. No pain initially, now heavy."
Scenario 2: The Wasting Hand
"A 60-year-old woman has wasting of her right hand. Thenar and Hypothenar eminence are flat. Sensation is reduced in the medial forearm."
Scenario 3: The Violinist
"A professional violinist complains of pain in the neck and numbness in the 4th/5th digits when playing. Adson's is positive."
Scenario 4: Recurrent Symptoms Post-Surgery
"A 35-year-old woman had first rib resection 18 months ago for NTOS. She presents with recurrent neck and arm pain similar to pre-operative symptoms."
MCQ Practice Points
Anatomy
Q: Which structure passes ANTERIOR to the Anterior Scalene muscle? A: The Subclavian Vein. (Artery and Plexus are posterior).
Clinical Signs
Q: What is the most sensitive test for NTOS? A: Roos Test (EAST).
Pathology
Q: Which muscle fibers are most affected in 'Gilliatt-Sumner' hand? A: Both Thenar (Median) and Hypothenar (Ulnar) - C8/T1.
Management
Q: What is the treatment for Venous TOS? A: Thrombolysis followed by First Rib Resection.
Cervical Rib
Q: Which type of TOS is almost always associated with a cervical rib? A: Arterial TOS (ATOS). Bony abnormality causes post-stenotic dilation and aneurysm formation.
Compression Site
Q: What is the most common site of compression in TOS? A: Interscalene triangle (between anterior and middle scalene muscles, above first rib).
Australian Context
Referral Pathways
- Neurogenic TOS: Often managed initially by Hand Surgeons or Peripheral Nerve Surgeons. May involve combined approach with Vascular Surgery for rib resection.
- Venous TOS: Urgent referral to Vascular Surgery - major centres include RPA (Sydney), Alfred (Melbourne), PAH (Brisbane).
- Arterial TOS: Vascular Surgery for arterial reconstruction and rib resection.
- Multidisciplinary: Complex cases benefit from combined Vascular, Orthopaedic Hand, and Physiotherapy input.
Telehealth consultations increasingly used for rural patients with suspected NTOS.
High-Yield Exam Summary
Anatomy
- •Triangle: Ant/Mid Scalene + Rib 1
- •Vein is Anterior to Triangle
- •C8/T1 Roots (Lower Trunk)
- •Subclavian artery passes through triangle
Types
- •Neurogenic (95%) - Pain/Numb
- •Venous (4%) - Blue/Swollen
- •Arterial (1%) - Emboli
- •Disputed - Subjective, no objective findings
Management
- •NTOS: Physio then Resection
- •VTOS: Lysis then Resection
- •ATOS: Resection + Graft
- •First rib resection is definitive treatment