Thoracic outlet syndrome TOS

TOS can involve a range of conditions which may compress or irritate the blood vessels and/or the nerves which pass through the region between the neck and the shoulder (the cervicoaxillary area).  As such it is more an umbrella term rather than a specific diagnosis.  Why?

The following is a list of SOME of the things which can lead to TOS (adapted from http://cdi.edu.au/diagnostics/drill14q3o.php

Congenital (born with) abnormalities include:

• Anomalies of C7 transverse process
• Cervical ribs
• Anomalies of first rib shape
• Enlarged scalene tubercle
• Variations in scalene muscle formation and insertion (including neural components travelling through its substance)
• Anomalies of costoclavicular ligament structure
• Anomalies of pectoralis minor or subclavius muscle structure

 

Trauma is another recognised cause of stretch or compression to the neurovascular bundle:

• Impact to the shoulder or neck
• Excessive bone remodelling after fractures of the clavicle or first rib
• Posterior subluxation of the acromioclavicular joint

 

Soft tissue causes implicated in TOS:

• Hypertrophy of the anterior scalene muscles (such as during increased use of the accessory muscles of respiration)
• Muscle fibre type adaptive transformation
• Spasm and excessive contraction following cervical spine injury
• Poor posture due to occupational stress and repetitive overuse – especially prolonged positions that include lowering of the anterior chest wall, forward slouching of the shoulders and forward movement of the head
• Excessive breast tissue

In effect an individuals symptoms may be due to one of the above or many (multifactorial) particularly as we age.


Douglas Scown