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Thoracic outlet syndrome (TOS)

  • Article
  • 2021-03-30

TOS is an umbrella term that encompasses three related syndromes in which the nerves, arteries and veins in the lower neck and upper chest are pinched and cause pain in the arm, shoulder and neck. Most doctors agree that TOS is caused by compression of the brachial plexus or subclavian vessels when passing through narrow passages leading from the base of the neck to the axilla and arm, but there is considerable disagreement over the diagnosis and treatment thereof.
Making the diagnosis of TOS even more difficult is that a number of conditions exhibit symptoms similar to TOS, including rotator cuff injury, cervical disc disease, fibromyalgia, multiple sclerosis, complex regional pain syndrome, and tumors of the syrinx or spinal cord. The disorder can sometimes be diagnosed on a physical examination by tenderness in the supraclavicular area, weakness and / or a 'tingling' sensation when raising the hands, weakness in the fifth ('little') finger and paleness in the palm of or both hands when the person raises them above the shoulders, fingers pointing towards the ceiling. Symptoms of TOS vary depending on the type.

  • Neurogenic TOS has a characteristic sign called the Gilliatt-Sumner hand where there is severe spillage in the fleshy base of the thumb. Other symptoms include paresthesias (sensation of tingling or numbness) in the fingers and hand, change in hand color, cold hands, or dull pain in the neck, shoulder, and armpit.
  • Venous TOS has pallor, a weak or absent pulse in the affected arm, which is also cool to the touch and appears paler than the unaffected arm. Symptoms may include numbness, tingling, pain, swelling of the limbs and fingers, and weakness of the neck or arm.
  • Arterial TOS are most noticeable with color change and cold sensitivity in the hands and fingers, swelling, heaviness, paresthesias and poor blood circulation in the arms, hands and fingers.

There are many causes of TOS, including physical trauma, anatomical defects, tumors pressing on nerves, poor posture causing nerve compression, pregnancy, and repetitive arm and shoulder movements and activity, such as playing certain sports.
TOS is more common in women. Symptoms usually start between the ages of 20 and 50. Doctors usually recommend nerve conduction, electromyography, or imaging studies to confirm or rule out a diagnosis of TOS.


Treatment begins with exercise programs and physical therapy to strengthen the chest muscles, restore normal posture and reduce compression by increasing the space of the area through which the nerve passes. Doctors will often prescribe nonsteroidal anti-inflammatory drugs (such as naproxen or ibuprofen) for pain. Other drugs include thromobolytics to break down blood clots and anticoagulants to prevent blood clots. If this does not relieve the pain, a doctor may recommend chest outlet decompression surgery to loosen or remove the structures that cause compression of the nerve or artery.


The outcome for individuals with TOS varies by type. The majority of people with TOS will improve with exercise and physical therapy. Vascular TOS and true neurogenic TOS often require surgery to relieve pressure on the affected vessel or nerve.

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