What is Thoracic Outlet Syndrome (TOS)?
Have you heard of Thoracic Outlet Syndrome or TOS? It is compression of neurovascular structures that course from the neck to the underarm through what's called the thoracic outlet.
The brachial plexus and subclavian vessels are particularly susceptible because of their proximity to each other in the thoracic outlet.
The most common site of compression is the space between the collar bone (clavicle) and the first rib. Other sites include between the scalene muscles and the first rib or the coracoid process and pectoralis minor muscle.
What are the symptoms of TOS?
Neck pain
Shoulder pain
Numbness or tingling of the arm, forearm or hand
There may be a feeling of weakness or early fatigue
The arm or hands may feel cool
Who gets it?
TOS can occur in people with occupations involving a lot of overhead work. The Syndrome is also associated with poor posture like drooping and or rounded shoulders, with some people predisposed to it if they are born with an unusual bone structure eg a complete cervical rib, fibrous bands on ribs or vertebrae, or hose with unusually shaped collar bones.
Of course, traumatic events, like large callous formation after a fractured collar bone, malunion or failed union of a collar bone or a crush injury to the upper thorax, can cause similar issues.
Muscle tightness or weakness can result in abnormal shoulder blade positioning (scapula dyskinesis) leading to TOS. This can include tight pectoralis minor, scalenes and upper trapezius or weak serratus anterior and lower trapezius muscles. This combination can lead to an tilting forward and protracted shoulder blade.
How do I know if I have it?
There are a couple physical tests we can do that can confirm the condition. We can also evaluate your shoulder blade motion and modify it to rule in or out scapula dyskinesia.
How can I treat it?
Depending on the cause, treatment may involve:
Posture correction
Change in work habits
Appropriate soft tissue and strength/ stretch work
Joint mobilisation of the first rib can restore motion of the joints either side of the collar bone (sternoclavicular and acromioclavicular joints)
Exercises and manual therapy to improve thoracic extension and neuro mobility
Arterial compression caused by an abnormal rib is usually treated with surgery