Causes

In general, TOS occurs when veins, arteries, and/or nerves are abnormally squeezed as they go through a small space called the thoracic outlet.  Most cases of TOS can be prevented!  

A variety of things can increase your risk of causing TOS:

• Birth defects- Having an extra first rib in your neck or an abnormally tight fibrous band (ligament) that connects your spine to your rib cage
• Poor posture- Large breasts, droopy shoulders or holding your head in a forward position

• Trauma- Car accident, whiplash (sudden jerking of the neck back and forth), or sports injury -  the onset of TOS symptoms is often delayed from the accident
• Repetitive arm or shoulder movements- Often seen in people who constantly type on a computer, working in a factory assembly line, baseball pitchers, swimmers, and carrying heavy shoulder loads (heavy bookbags and purses)
• Weightlifting- Lifting heavy objects above your head repeatedly
• Tumors or large lymph nodes in the upper chest or underarm area

Heavy Lifting Over Your Head