Thoracic Outlet Syndrome

What is thoracic outlet syndrome?

Thoracic outlet syndrome (TOS) is a term used to describe a group of disorders that occur when there is compression, injury, or irritation of the nerves and/or blood vessels (arteries and veins) in the lower neck and upper chest area. Thoracic outlet syndrome is named for the space (the thoracic outlet) between your lower neck and upper chest where this grouping of nerves and blood vessels is found.

What causes thoracic outlet syndrome?

The disorders caused by TOS are not well understood. Yet, it is known that when the blood vessels and/or nerves in the tight passageway of the thoracic outlet are abnormally compressed, they become irritated and can cause TOS. Thoracic outlet syndrome can be a result of an extra first rib (cervical rib) or an old fracture of the clavicle (collarbone) that reduces the space for the vessels and nerves. Bony and soft tissue abnormalities are among the many other causes of TOS.

The following may increase the risk of developing thoracic outlet syndrome:

  • Sleep disorders
  • Tumors or large lymph nodes in the upper chest or underarm area
  • Stress or depression
  • Participating in sports that involve repetitive arm or shoulder movement, such as baseball, swimming, golfing, volleyball and others
  • Repetitive injuries from carrying heavy shoulder loads
  • Injury to the neck or back (whiplash injury)
  • Poor posture
  • Weightlifting

Who is affected by thoracic outlet syndrome?

Thoracic outlet syndrome affects people of all ages and gender. The condition is common among athletes who participate in sports that require repetitive motions of the arm and shoulder, such as baseball, swimming, volleyball, and other sports.

Neurogenic TOS is the most common form of the disorder (95 percent of people with TOS have this form of the disorder) and generally affects middle-aged women.

Recent studies have shown that, in general, TOS is more common in women than men, particularly among those with poor muscular development, poor posture or both.