Thoracic outlet syndrome

🩺 About

• Thoracic Outlet Syndrome (TOS) = compression of neurovascular structures (brachial plexus, subclavian vein/artery) as they pass between the clavicle and first rib.
• Leads to pain, weakness, numbness, and sometimes vascular compromise (swelling, coolness, cyanosis).
• Can present as neurogenic (most common), venous, or arterial TOS.

⚠️ Aetiology

• Compression of lower brachial plexus roots (C8 & T1) by:
  • Fibrous band between C7 transverse process & first rib.
  • Cervical rib (visible on CXR).
  • Postural/anatomical narrowing of thoracic outlet.
  • Repetitive overhead activity (e.g. athletes, violinists, manual labourers).

👩‍⚕️ Clinical Features

• Young adults, more common in females.
• Neurogenic TOS (most common, 90–95%):
  • Pain/paraesthesia along ulnar border of forearm & hand.
  • T1 sensory loss, weakness & wasting of thenar muscles (esp. abductor pollicis brevis 💪).
  • ± Horner’s syndrome (ptosis, miosis, anhidrosis).
• Venous TOS 🫀:
  • Arm swelling, cyanosis, venous distension.
  • May present with effort thrombosis (Paget–Schroetter syndrome).
• Arterial TOS 🫁:
  • Cool, pale arm; diminished pulses.
  • ± bruit or digital ischaemia.
• Symptoms worsen with overhead arm positions (e.g. hanging washing, hair drying).

🔬 Investigations

• CXR 📷: cervical rib or bony abnormality.
• CT/MRI 🧠: defines fibrous bands, masses, or bony anomalies.
• Doppler Ultrasound 🩸: dynamic testing with arm elevation for vascular compromise.
• Nerve conduction studies: in suspected neurogenic TOS.
• Provocative bedside tests (Adson’s, Wright’s, Roos) are suggestive but not diagnostic.

💊 Management

• Conservative (first-line):
  • Physiotherapy 🏋️‍♀️: posture correction, chest/neck/shoulder stretches.
  • Avoid heavy shoulder bags 🎒, overhead activity.
  • Pain relief: NSAIDs/paracetamol.
  • Weight loss if contributory.
• Interventional:
  • Surgery reserved for refractory/severe cases:
    • First rib resection ± scalenectomy.
    • Approach: supraclavicular or transaxillary.
  • Vascular TOS: may need thrombolysis, venoplasty, or bypass in addition to decompression.
• Most improve with physiotherapy, but untreated severe TOS risks permanent nerve/vascular damage ⚠️.

📚 References

• NCBI – Thoracic Outlet Syndrome
• StatPearls – TOS overview

Cases - Thoracic Outlet Syndrome (TOS)

• Case 1 - Neurogenic TOS (Most Common) 🧠: A 32-year-old office worker presents with numbness, tingling, and weakness in the ulnar distribution of the right hand, worse when carrying heavy bags. Exam: reduced grip strength, wasting of hypothenar muscles, symptoms reproduced with arm elevation (Roos test positive). Diagnosis: Neurogenic thoracic outlet syndrome. Management: Physiotherapy (posture, stretching of scalene/pectoral muscles), analgesia; surgical decompression if severe/progressive.
• Case 2 - Venous TOS (Effort Thrombosis, Paget-Schroetter) 💙: A 25-year-old rower develops sudden right arm swelling, cyanosis, and heaviness after intense training. Exam: engorged veins over shoulder and chest wall. Doppler US: subclavian vein thrombosis. Diagnosis: Venous TOS (Paget–Schroetter syndrome). Management: Catheter-directed thrombolysis, anticoagulation, surgical decompression (first rib resection or scalenectomy).
• Case 3 - Arterial TOS (Rare but Serious) ❤️‍🔥: A 40-year-old woman presents with coldness, pallor, and intermittent claudication of the right hand, worse with overhead activity. Exam: diminished radial pulse with arm elevation (Adson’s test), bruit over subclavian artery. CT angiography: subclavian artery compression with post-stenotic dilatation and distal emboli. Diagnosis: Arterial thoracic outlet syndrome. Management: Anticoagulation/antiplatelets, surgical decompression and arterial reconstruction if symptomatic or embolic complications.

Teaching Commentary 🧠

Thoracic outlet syndrome = compression of neurovascular bundle (brachial plexus, subclavian vein, subclavian artery) between scalene muscles, first rib, and clavicle. - Neurogenic (90%): sensory/motor symptoms in ulnar distribution. - Venous: swelling, cyanosis, effort thrombosis. - Arterial: ischaemia, claudication, emboli. Dx: Clinical tests (Adson’s, Roos), Doppler/CT angiography, EMG. Mx: Conservative physio first (posture, muscle stretching), surgical decompression for vascular or refractory cases.