myosesh Musculoskeletal post,Myotherapy Thoracic outlet syndrome (TOS)

Thoracic outlet syndrome (TOS)

This is the term used for neurovascular entrapment at the thoracic outlet, which effect the nerves of the brachial plexus, subclavian artery and vein


  • Shoulder and lower cervical trauma (injury) *5
  • Repetitive activities such as typing and pitching
  • Extra cervical rib
  • Hypertonicity of pectoralis minor and scalene
  • Poor posture like rounded shoulder, forward head carriage

*Abnormalities such as extra rib or prolonged transverse process are prone to develop TOS. *5

There are 4 kinds of conditions. They are

  1. Costoclavicular syndrome

This is the most prevalent that there is compression in the costoclavicular space between the clavicle (collar bone) and first rib

  • Scalenus anterior syndrome

There is compression between anterior and middle scalene and upper border of the first rib

  • Pectoralis minor syndrome (Hyperabduction syndrome)

Where compression between the angle of coracoid process and insertion of pectoralis minor especially when the arm is abducted

  • Cervical rib syndrome

Some people have this condition. This is compression is caused by an additional cervical rib at C7

Sign and symptoms

  • Nerve irritation pain such as shooting pain, numbness, weakness, pins and needles and tingling
  • Swelling and due to artery or venous compression
  • Weakness of the arm and get tired easily
  • Pain down to the medial aspect of arm and hand
  • Pain often nocturnal, disturb sleep with pain or numbness
  • Difficulty in gripping and fine finger movement
  • May be associated with a headache


  • Stretch and treatment on scalene and pectoralis minor
  • Keep good posture including sleeping posture
  • NSAIDs
  • Antidepressant for pain
  • Anticoagulant for vascular compression to reduce risk of clot

Special test

   ·Eden’s test for costoclavicular

   ·Adson’s test for scalenus anterior syndrome

   ·Wright’s test for hyperabduction syndrome

   ·Roos test for artery of brachial plexus

Differential Diagnosis

Classic TOS is that the lowest fibre of brachial plexus (T1) gets damaged which means that people with TOS feel numbness in ulna side (little finger and ring finger) while carpal tunnel syndrome is that median nerve gets affected, which people feel numbness in middle finger and index finger and weakness in base of the thumb. However, C5-C6 may be compressed by middle scalene muscle.

Although people feel and describe pain differently, it is said that referral pain of pectoralis major, minor and latissimus dorsi go from shoulder all the way to little finger and ring finger.

Pec major trigger point referral pain
Pec minor Trigger point referral pattern

Referral pain is sometimes described as numbness. Therefore, trigger point may bewilder practitioners.

If the problem is caused by trigger point, ROM test (AROM, PROM and RROM) will reproduce the pain. Otherwise, special test can help to identify the cause.

Of course, questioning what aggravating factors and easing factors are can help find out what is going on.


  1. Jacky Laulan, Bernard Fouquet, Camille Rodaix, Penelope Jauffret, Yves roquelauren and Alexis descatha Thoracic outlet syndrome: definition, aetiological factors, diagnosis, management and occupational impact 2012 J Occupation Rehabilitation 21 (3): 366-373  
  2. Roos DB congenital anomalies associated with thoracic outlet syndrome Am J Sung 1976 132: 771-778
  3. Roos DB. Thoracic outlet syndromes: Update 1987. Am J Surg. 1987;154:568–73. 

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