Thoracic outlet syndrome

Symptoms occurring due to compression of structures like
- Brachial plexus (95% of cases)
- Subclavian vein (4% of cases)
- Subclavian artery (1% of cases)
Caused by narrowing of the anatomical opening called “thoracic inlet”, “thoracic outlet” or “superior thoracic aperture”, which is a hole surrounded by
- Clavicula
- The first rib
- Scalenus anterior
- Scalenus medius
If the thoracic outlet becomes narrower some or all of the neurovascular structures may be compressed
Etiology
- Trauma
  - Collarbone fracture
- Hypertrophy of scalenus muscles
- Pancoast tumor
- Congenital cervical (extra) rib
Clinical features
- Neurogenic thoracic outlet syndrome
  - Due to compression of brachial plexus
  - Pain, anaesthesia, paraesthesia in neck and arm
  - Often in areas innervated by ulnar nerve
- Venous thoracic outlet syndrome
  - Due to compression of subclavian vein
  - Swelling
  - Venous distension
  - Venous thrombosis
- Arterial thoracic outlet syndrome
  - Due to compression of subclavian artery
  - 4 Ps
    - Pulselessness (in the hand)
    - Pain
    - Pallor
    - Paraesthesia
Treatment
- Physical therapy
  - In mild cases, can be enough
- Thoracic outlet decompression surgery
  - Transaxillary resection of extra rib or first rib
  - Angioplasty, if vessels are affected
Cervical rib
- Some people have a congenital extra rib before the first rib called the cervical rib
  - The first rib starts at Th1
  - The cervical rib starts at C7
- This cervical rib compresses the thoracic outlet, causing TOS
- The treatment is surgical resection of the cervical rib