Thoracic Outlet Syndrome

The thoracic outlet is a narrow passageway between the collarbone and the first rib that is crowded with blood vessels, muscles, and nerves. Weak shoulder muscles in the chest may not hold the collarbone in place, causing it to slip down and compress the nerves and blood vessels that lie beneath it.

There are three types of thoracic outlet syndrome (TOS), each with their own symptoms and causes.

Type 1. Neurogenic TOS: 95% of cases of TOS are due to compression of the nerves to the arm


  • Pain, numbness, tingling, or weakness in the arm and hand
  • Tired feeling in the arm, made worse by working with arms raised over the head
  • Neck pain and headaches in the back of the head
  • Pain that starts in the shoulder and runs down the arm, as well as pain in the fingertips
  • Weakening grip


  • Neck trauma such as whiplash injury
  • Slipping and falling
  • Repetitive stress from working on assembly lines or keyboards
  • Scar tissue formation in neck muscles
  • Development of a rounded shoulder and forward head posture due to improper ergonomics
  • Muscular tension and imbalances leading to postural deviations'

Type 2. Venous TOS: 3–4% is due to obstruction or clotting of the main vein to the arm, subclavian vein.


  • Swelling in the entire arm
  • Pain and dark discoloration
  • Weak or absent pulse in affected arm, which may be cool to the touch
  • Numbness, tingling, aching, and heaviness
  • Throbbing lump near the collarbone
  • Tiny black spots (infarcts) on fingers


  • Strenuous use of the arm and shoulder
  • Congenital narrowing of the space through which the major arm vein (sublclavian vein) passes from the shoulder area to the heart

Type 3. Nonspecific–type TOS: occurs when there is chronic pain in the area of the thoracic outlet, but the specific cause of the pain can't be determined.


  • Dull, aching pain in the neck, shoulder, and armpit
  • Gets worse with activity


  • Traumatic event such as a car accident or a work related injury
  • Common in athletes, including weight lifters, swimmers, tennis players, and baseball pitchers

Risk Factors:

  • Gender- more common in women
  • Age - symptoms usually occur between 20 and 50 years of age
  • Pregnancy -because joints loosen during pregnancy, signs of TOS may first appear while pregnant

Physical therapists can diagnose this syndrome and speed recovery through performing specific manual techniques to restore alignment and space required in the thoracic outlet while stretching muscles and reducing neural tension. Therapists will develop specific exercise programs to further stretch tightened muscles and strengthen weakened postural muscles. Therapists also educate about ergonomics, posture, and prevention.